LOSSES IN MAKING

AND SILAGE

by J. A. LeClerc ^

H L R t is a thoroughgoing account of the losses that may be expected in hay and silage as compared with the fresh plant material. Under each heading the author first gives a general account, with recommendations, and follows this with a detailed summary of experimental data, including much technical material. He describes the newer methods of handling crops—including the use of cakes made of fresh grass—and the most important methods of preparing silage.

HAY

UNTIL a very few years ago field curing w^as practically the only method ever used m preparing hay for storage. Considering the fact that even with normal practice and under normal weather condi- tions, haymaking in many sections of this country is accompanied by a loss of dry matter amounting to 10 percent or more, it follows that the loss to farmers each year may amount to at least 75 million dollars. If the w^eather during haying is unfavorable, the loss in nutritive value may easily be several times as great as normally, entailing a correspondingly larger financial loss. Studies of hay crops cured and stored by traditional methods as compared wàth newer methods appear to support the following conclusions: 1. Field curing of hay, under ordinär}^ conditions, is always accom- panied by appreciable mechanical losses of leaves—that portion of the crop richest in dry matter, protein, vitamiîis, and minerals. 2. Losses of valuable constituents of the hfij as the result of rain may account at times in certain localities for as much as half the value of the crop (hence the old adage, ''Make hay while the sun shines'0. 3. Losses by artificial drying are small compared to those by field cming.

1 J. A. LeClerc is Senior Chemisr. Food Researcii Divisiüii, Bureau of Chemistry- and Soils. 992 LOSSES IN HAY AND SILAGE 993 4. Artificial drying can be done in any weather. There is no loss from leaching, little loss of carotene, and little or no loss from shatter- ing of leaves. The product is a better feed than is the ordinary field- cured product. 5. Since the leaves are the most nutritious portion of the crop, it is essential to cut the hay when the leaves are in greatest abundance. Artificial drying of hay is the surest way to save the greatest pro- portion of the leaves. 6. The utilization, by artificial drying, of young grass (before the nodes are formed) might prove of great monetary value to farmers, especially in certain sections of this country where weather conditions are favorable for the growth of grass, and where there is a lack of concentrated feeds. 7. The processing of young dried grass (before the stems are formed) into so-called grass cakes by compressing machines appears from English experiments to have promise. This process might prove w^orthy of study in certain sections of the United States. 8. Young-grass cakes appear to have unusual food value. A study of the chemistry and feeding value of young grass may reveal factors, now unknown, which have an important bearing on the health of animals and man. 9. The utilization of young grass appears to be a means of increas- ing the national wealth by assuring better health to animals through a supply of feed richer in essential minerals and vitamins than many of the feeds ordinarily used, and consequently producing more nutri- tious animal food for man. The conservation of young grass promises to play an important role in the agriculture of certain parts of this country. DATA ON HAYMAKING AND ON NEWER METHODS

Losses in Field-Cured Hay

According to Fleischmann {36/}.),- the field curing of hay is always accompanied by profound changes in the constituents, even though the losses may be slight, and hence it is not correct to refer to dried hay as ''low-moisture green /' The losses of total dry matter during haymaking may vary from 10 to 30 percent; of digestible dry matter, from 15 to 35 percent; and of starch equivalent (1 pound of starch equivalent has an average net energv value of 1.071 therms {819)) from 25 to 50 percent, A picture of the losses in dry matter and protein is found in tables 1 and 2, which give figures for green and for field-cured alfalfa hay.

TABLE 1,—Weight and percentage of dry matter and protein in 1 ton of green alfalfa^

Item Tota crop Lea ves Stems

Pounds Percent Pounds Percent Pounds Percent Green crop------.. -- - 2,000 100 1.100 55 990 45 Drv matter 580 29 220 20 360 40 Protein in the green alfalfa - -. . -.... 92.4 4.62 52.8 4.8 39.6 4.4 Protein in the dry matter on basis of no loss of leaves or stems 15. 93 24.0 11.0

1 Basis of calculation: Leaves in green crop. 55 percent. Loss of leaves, 30 percent; of stems, 10 percent.

2 Italic numbers in parentheses refer to Literature Cited, p. 1075. 141394^^—30 m 994 YEARBOOK OF AGRICULTURE, 1939

TABLE 2.—Portions of the green crop saved or lost on curing

Portion saved Portion lost Proportion saved or I lost of— Total crop ; Leaves Total crop ; Leaves Stems

ios. Pet. Lbs. Pet. \ Lbs. Pet. \ Lbs. Pet. Lbs. Pet. Green crop 1,580 70 810 90 ! 420 I 21 j 330 30 90 10 Dry matter 478 70 i 324 90 ' 102 i 17.6 i 66 30 36 10 Protein of green al- falfa- 72.6 70 ' 35.64 90 19.80 i 21. 5 i 15.84 30 3. 96 10 Protein of crop I 15.2 24.0 ! 11.0 i 19.4 24 11

On the basis that during held curing there is a loss of 30 percent of leaves and 10 percent of stems, 1 ton of green alfalfa will yield 478 pounds of drv matter, con- sisting of 1.54 pounds of leaves and 324 pounds of stems. The amount of protein in the dried crop will be 72.6 pounds, of which 36.96 is in the leaves and 35.64 in the stems. When compared to the amount of dry matter and of protein in the 2,000 pounds of green alfalfa, these figures represent a loss of 102 pounds of dry matter during the curing process, equivalent to 420 pounds of the original green crop; and likewise a loss of 19,8 pounds of protein. In other words, 21"percent of the green crop (equivalent to 17.6 of the dry matter and 21.5 percent of the pro- tein) was lost during field curing.

TABLE 3.—Composition, digestibility^ and digestible nutrients in field grass and early hay. on dry basis

Coniposition Digestibility T^igestible nutrients

Constituent p , Hay Hay Hay Hay Hay Hay lllf' from from Fresh Fresh grass from from from from ^^^^^ field stacks field stacks field stacks

Percent 'Percent ^Percent Percent \Percent Percent Percent Percent Percent Fat (ether extract) ¡ 1.9 1. ' 2.0 57. 7 ! 41. 0 ! 44. 0 1.1 0.76 0.87 Crude fiber | 24.6 24.0 26. 9 77. 5 I 76. 3 ; 77. 9 19.1 18.3 20. 9 Crude protein. U.8 12.2 12.9 68. 9 1 66. 5 i 48. 5 8.1 8.1 6.3 Minerals (ash) '.6 S.2 (- free extract) 54,3 Ô0.0 81. y 79. 9 70.4 44.3 3.4 35.2 True protein 9.9 10.4 67.1 62. G 48.3 7.0 6.2 5.0 Lime (calcium oxide) .58 .72 Phosphoric acid (phospho- rus pcntoxide) Starch equivalent. 63.7 55.0 47.0 Protein equivalent 7.4 7.2 5.7 Dry matter in fresh ma- terial 24.8 74.7 74. Í

The losses in field-cured hay have been apportioned by Wiegner (1218) as shov/n in table 4.

TABLE 4,—Distribution of losses of dry matter and of starch equivalent as the result of field curing of hay

Dry matter Digestible Starch equiv- dry matter alent

Percent Percent Percent Respiration of crop Up to 10 5-15 5-15 Mechanical injury 5-10 5-10 ; 5-10 in the stack 5-10 5-10 i 5-10 Metabolic processes in the animal. 10-15 Total 15-35 ! 25-50 LOSSES ÍN HAY AND SILAGE 995

On the basis of a 26,000,000-ton crop of alfalfa, the loss of dr^^ matter and of protein would be 1,326,000 and 257,000 tons, respectively. Besides this tremendous loss of protein and dry matter as the result of ordinary field curing, the loss of 30 percent of leaves during this process involves corre- spondingly large losses of calcium, phosphorus, and other essential minerals, for the leaves are the richest part of the plant in minerals as well as in protein and vitamins. Watson, Ferguson, and Horton {1194) analyzed fresh grass, hay from the field, and hay from stacks with the results shown in table 3. Under quite different haymaking conditions, of course, the results might be materially different. Losses in Curing The classical researches of Fleischmann (364) in Germany constitute the most important contribution to the study of hay and the losses that take place during field curing. Until this study was made it was generally believed that if the hay was cut and dried under favorable conditions, unaccompanied by any loss of leaves, the dried hay retained unchanged, and in toto, the feed constituents present in the green crop, and that the only difference between the freshly cut grass and the field-cured hay was physical and in the moisture content. Some of Fleischmann^s general conclusions are well worth reproducing here. It is a question, of course, whether European data can be applied to this country, especially to those localities where drying of hay in the field can be completed in at most 2 days owing to continuous sunshine. In Europe because of rains or heavy dew field curing frequently requires several days. (ly If hay is dried the same day it is cut the loss, if any, will be small. (2) Slow drying (as on a sunless day) causes losses in dry matter of 4 to 13 percent. The longer the time required to dry, or the higher the temperature of drying in cloudy weather, the greater the loss of dry matter. (3) The loss of dry matter ceases, however, when the partly dried hay still contains 38 percent of moisture (or, in other words, when hay has lost 87 percent of its original moisture) even though drying still be continued. (4) The loss (about 9 percent) due to vitaJ activity (enzymes) is considerably more than the loss (2 to 4 percent) due to micro-organisms. (5) The drier the grass the greater the possibility of loss due to leaching from rain. When fresh or partly wilted grass is rained upon, the losses are due chieñy to activity within the cells. If wilted or dried hay becomes wet some loss may be caused also by . (6) In live grass the loss due to bacteria is small. In dead grass this loss may reach 20 percent. (7) In freshly cut and freshly made hay the content of lecithin (a fatlike sub- stance containing phosphorus) averages about 88 milligrams per 100 grams of dry matter; in stored hay only 20 milligrams are left, a loss of 75 percent. (8) The amount of protein nitrogen is always greater in the freshly cut grass than in hay (calculated on the same moisture content). On the other hand, the amount of amides (protein decomposition products) is always greater in hay. During haying there is always a loss of protein nitrogen but not of total nitrogen. This loss is due to activity within the cells. Freshly cut hay may contain as little as 9 percent of amide nitrogen and dried hay as much as 33 percent, especially if this hay has been dried under unfavorable conditions. (9) There is always a loss of fat during haymaking, and this may be as high as 40 percent. This loss occurs whether the hay is dried in the sun or in the shade. The decrease in fat is correlated with the decrease in dry matter. (10) Ño change has been noted in the crude fiber content. (11) The loss of starch is significant if the hay is dried slowly, but when the drving is done quickly the loss is reduced to a minimum. (12) The percentage of sugars decreases with the length of time of drying and with the temperature. In a growing plant ingredients move from one part of the plant to another, especially tow^ard maturity (151). In the drying of grass to hay there is a con- tinuation of this interchange of ingredients. According to Watson {1187), the losses by shattering of leaves, leaching, fermentation in the stack, the destruction of the carotene, etc., when hay is made in the ordinarv way, may in the aggregate amount to 25 percent or more of the food value of the hay. Studies in Norway have shown average losses of 20 percent. In ordinary hay curing there is always a natural fermentation going on, with more 996 YEARBOOK OF AGRICULTURE, 1939 or less production of heat, depending largely on the moisture content. The niaximum temperature as the result of this fermentation is attained in about 10 days. A secondary fermentation is noted about 3 weeks after tlie hay is stacked. The highest temperature noted in some of these experiments was 150° F. Under average conditions of haymaking in the British Isles the losses in feed value from harvesting to storing in stacks may amomit to 30 percent or more of the starch equivalent and digestible crude protein, and in unfavorable weather these losses may even exceed 50 percent (1189). The losses that take place in the field and in stacks with both early hay and ordinary hay were studied by Watson and his associates (1194), with the results shown in table 5.

FABLE 5.^—Losses of feed constititejits thai take place in raring hay

In field In stack« Constituent

Early Ordniary Early ¡Ordinary Early Ordinary hay hay hay hay hay hay

Percent Percent Percent Percent Percent Percent Dry matter 18.0 14.3 5.2 5. 7 23.2 20.0 Crude protein.... _ 14.3 18. ó 2.2 2.7 16.5 21.7 Starch equivalent- 34. 5 2r,. 7 i\. 8 5.3 41.3 32.0 Protein equivalent 23. 0 33. 7 9.0 1 +4. 3 32.0 29.4

' Giiin. During favorable years the losses of dry matter and of starch equivalent in ordinary hay averaged 8 and 20 percent, respectively; in bad years, 34 and 47 percent. With early hay the respective losses were 13 and 25 percent in good years, and 23 and 44 percent in bad seasons.

TABLE 6.—Total nitrogen, protein nitrogen, and amide nitrogen in grass dried under dißerei it con dit i o n s <^ ^ - c Xitrogcn in water- Nitrogen in water- c Iree substance an- free orisfinal sub- Total ni- alyzed stance trogen

j^ .j, , How or where dried Kind of trrass. c > ^'>i ■^ 6 . 0 S tí 0 ■5 fl 71 tí! .3 ■ c 3 si ■ .11 0 P 2- £ : a < Hr M <

nays TIrs. °C. Pet. Pd. Pet. Pet. Pet. Pet. Pet. Pet. Pr.f Vacuum ' Festuca pra- 3 98 23.0 2.29 2.01 0.28 2.29 2.01 0.28 88 12 tensis. Greenhouse -_ .-do ti 12 14 20.6 2.44 1.94 .50 2.18 1.73 .45 79 ?.] Cellar _...-do 7 12 11 2J.1 2.43 1.78 .65 2.23 1.63 .60 73 27 Room --...do 4 0 14 21.2 2.47 1.86 .61 2.28 1.72 .56 75 25 Vacuum' Poapraten- 3 98 26.1 2.92 2.67 .25 2.92 2.67 .25 91 9 sis. Greenhouse do 7 0 15 24.1 3.30 2.36 .94 3.05 2.18 .87 72 : 28 Vacuum i d 98 20.2 3. 36 2.98 .38 3.36 2.98 .38 89 n sativa. Shade do 5 0 16 IS. S 3.66 2.45 1.21 3.36 2. 25 1.11 67 ■ 33 Greenhouse --.-.do G Ü W 18.2 3.68 2.22 1.46 3.32 2.00 1.32 60 40 Wilted in cellar do--—-_ 7 0 13 19.0 3.54 2.00 1.54 3.32 1.88 1.44 57 43 Vaeuumi Mixed grass- 3 98 22.0 3.91 3.31 .60 3.91 3.31 .60 85 15 In sun do 5 {) 9 21. 1 4.06 3.11 .95 3.90 2.99 .91 77 23 Cellar do S 0 14 21.3 3.87 2.77 1.09 3.74 2.68 1.06 72 '■ 28 Vacuumi Grass No. 1- 3 08 21. ß 3.15 2.83 .32 3.15 2.83 .32 90 i 10 In sun do 2 0 19 20.7 3.22 2. 63 .59 3.08 2.52 .56 82 18 Shade r-_-.do 3 12 20 19.5 3.44 1.90 1.54 3.10 1.71 1.39 55 45 l---do 4 12 18 18.5 3.56 1.83 1.73 3.04 1.56 1.48 51 i 49

Î Control. LOSSES IN HAY AND SILAGE 997

Fleischmaiin's elaborately conducted experiments (364) in drying hay (I) in a vacuum^ (2) in the greenhouse, (3) in the cellar, (4) in shade, and (5) in sun, show that under certain conditions nearly one-half of the protein niay be broken down into amides. This is especially true when the hay is being dried for several days in the shade. When dried under good conditions, however, hay may con- tain as little as 10 percent of amide nitrogen (table 6). The loss of leaves during the field curing of alfalfa under good conditions varies from 5.9 percent to 9.2 percent (see the article, The Nutritive Value of Har- vested , p. 968). This is an important factor, for leaves are the richest part of the plant in food nutrients. Leaves of ha^^s constitute one-fifth of the weight of the plant. After the milk stage these leaves contain nearly one- half of the minerals and 40 percent of the fat of the whole plant {1091).

Losses Through Leaching Experiments conducted long ago in the Bureau of Chemistry showed that at least 30 percent of the phosphorus, 65 percent of the potash, and 20 percent of the nitrogen may be washed from dried plants by rain (67^). More recent experi- ments by Guilbert, Mead, and Jackson (44^) show that losses from leaching may be as high as 67 percent of the minerals, 35 percent of the carbohydrate (nitrogen-free extract), and 18 percent of the protein. Only a slight loss of fat was noted. The crude fiber content of leached plants was actually higher than before leaching, owing, of course, to the large losses of the other constituents.

Losses in Undercured or Wet Hay It is well known that hay stored in mows or stacks in an undercured condition or cured hay allowed to become wet from any cause after storage is subject to excessive spontaneous heating, and such heating may progress to temperatures sufficiently high to produce ignition. The annual fire loss in the United States due to the spontaneous ignition of hay has been estimated as high as $20,000,000. The spontaneous heating may stop short of ignition, but even then the hay will suffer very serious deterioration and often complete destruction of its feeding value. Losses of this nature probably are even greater than the losses from fire. In brown and black alfalfa, which is made by stacking partly wilted alfalfa with air excluded, Swanson, Call, and Salmon (lll2) found enormous losses in protein, crude fiber, carbohydrate (nitrogen-free extract), and fat (ether extract). Truninger {1151) found that excessive fermentation in storage resulted in losses of nitrogen-free extract as high as 40 percent. In only one case was the loss of digestible pure protein less than 50 percent, and in some cases it was complete. Hoffman and Bradshaw {526) report very serious losses of organic substance in the storage of alfalfa of high moisture content. The losses involved chiefly the fats (maximum 47 percent), the sugars (maximum 94 percent), and the hemicel- lulose group—the more digestible portion of the plant framework (maximum 52 percent). Under the more extreme conditions cellulose and crude protein also were attacked. It is generally agreed that the initial production of heat in a mass of undercured or wet hay is due mainly to the respiration process of the living plant cell and to the activity of micro-organisms. These agencies are capable of raising the tem- perature of the hay to as high as 158° F. or slightly higher. Temperatures above this (the death point of micro-organisms) cannot be due to biological causes. In the eJBfort to account for the sul^sequent rapid rise of temperature that is neces- sary to produce ignition, various and sometimes conflicting hypotheses have been proposed. That of Browne {162) appears to be the most deserving of considera- tion. It is based on the assumption that micro-organisms in the absence of first produce unsaturated, highly unstable intermediate fermentation products whose subsequent oxidation generates the heat that may ultimately lead to ignition. Losses of Vitamins During sun curing of hay a considerable proportion of the carotene is destroyed Gordon and Hurst {426) show that sun-cured alfalfa contains 36 parts per million of carotene, or only about one-third that found in artificially dried hay. The relative amounts of carotene in sun-dried and artificially dried lespedeza was 998 YEARBOOK OF AGRICULTURE, 1939 found to be 52 and 75 parts per million, respectively; in , 17 and 27; and in soybean hay, 42 and 64, The carotene content of artificially dried grass was found by Watson {1187) to be 34.5 milligrams in 100 grams; that of A. I. V. silage, 46 milligrams; that of low-temperature silage, 39.5 milligrams; and tliat of meadow hay, only 1.5 milli- grams. As much as 80 percent of the carotene may be lost during the first 24 hours after cutting (998), most of this loss being due to enzymic action associated with favorable moisture and temperature conditions. Hay cured away from ultraviolet light—^for example, indoors—or V)y artificial heat in a drier retains most of its vitamin A {1076). Intermittent sunshine and rain while alfalfa is in a swath causes the alfalfa to become bleached as well as to suffer an almost total loss (96 percent) of its vitamiii A. Vitamin Bi in hay is present to the extent of 1 to 3 International Units per gram. This vitamin, being easily destroyed by heat, can deteriorate in storage and during the harsh treatment of curing to the point of almost total destruction {1162). When hay is exposed to rain it loses a considerable proportion of its vitamin G. Exposure to dry weather even for 4 days did not, however, affect the G content {561). While curing hay in the sun causes it to lose its vitamin A, curing in the absence of light prevents the development of vitamin D. Synthesis of vitamin D occurs only when alfalfa is cured in the sun {1076). Artificially Dried Hay Researches and experiments during the past few years have shown that methods other than field curing for the preparation of hay for storage were deserving of attention. The freshly cut grass besides being field-eured can now^ be ensiled, artificially dried, or, as is sometimes done in England, dried and compressed into ^^cakes." Ensiled or compressed hays have the advantage that they cannot easily be set on fire, whereas hay in stacks or in mows is ahvays a fire hazard. In the study of hay in the laboratory it was noted that when the hay was dried quickly in preparation for chemical analysis, it lost little or no dry matter, whereas the same hay dried in a cool, well-veiitilated room lost 6 to 12 percent of dry matter {364). This difference quite naturally suggested quick drying of freshly cut grass in order to miniixiize the loss of dry matter. At present only an insignificant percentage of the hay crop is thus quickly (or artificially) dried; in fact, not much over 100,000 tons. '^ In the United Kingdom and on the continent of Europe a still smaller tonnage of hay is thus prepared. The object of drying green crops artificially is to retain tbe various factors that characterize hay of good quality. There are several types of driers—tray, belt, rotary, and pneumatic. These different forms of driers are as follows {971): (1) Tray driers are batch driers in w^hich the grass is liand-shaken from one tray to another, halfw^a}^ through drying, in order to facilitate even drying; (2) belt driers, in which the fresh grass is put in at one end and emerges dry at the other without Iiandling; (3) rotary or drum driers, in which the grass is dried in a revolving drum, the herbage being agitated mechanically while under the influence of the furnace gas; (4) pneumatic driers, in which the grass is dried as it is carried along in the drying current. The expense of artificial drying is an important consideration, A drying machine must pay for itself by producing a product of greater monetary and nutritive value than field-cured hay. In artificial drying the losses of nutrient constituents, if any, should not exceed 5 percent unless excessive shattering of leaves takes place. In general, the tem- perature of drying is a minor factor in affecting the quality of the product, pro- vided it is removed from the drier as soon as dry. So long as the plant has moisture that can be evaporated it will not be injured during the drying process. A pneu- matic drier with an initial or inlet temperature as high as 1,472° F. may produce dry grass of excellent quality {971). Experiments in drying grass indicate that the inlet temperature of 250° to 350° F. did not affect the digestibility of young dried grass, although with an initial temperature of 400° the grass lost appreciably in digestibihty of the protein during 2 to 5 minutes of drying {522). Other experiments show that a temperature of 480° to 535° F, for 40 seconds LOSSES IN HAY AND SILAGE 999 did not reduce the availability of the protein or calcium {490). Grass dried by direct heat in a kiln at 239° for 3 hours was only slightlv less digestible than when dried with steam at 212° {1257). It has beea demonstrated that the temperature of the drying gas does not affect the carotene content of hay or the digestibility of the protein {1187), as table 7 shows.

TABLE 7.—Carotene content and the digestibility of the protein of hay dried at different temperatures

Results at a gas tempérai are of

1,112° 482° F, i 662° F. '■ F.

Carotene content, per 100 grams of dry matter. milligrams _ _ : 26. 8 ; 30. 7 Digestibility of crude protein percent__! 77,8 76.7

It has been shown by Kane and coworkers {607) that ordinary market hay may frequently contain as little as one-tenth the carotene in the green crop, and that alfalfa quickly dried in a tunnel drier at 260° to 264° F. may have as much as seven times the vitamin A content found in poor-quality hay; that when alfalfa was dried in a rotary drum, being momentarily exposed to a temperature of 1,200° to 1,382°, its carotene content was almost as high as in the freshly cut crops and 2 to 10 times as much as in the field-cured alfalfa. If, however, the artificially dried alfalfa is subsequently exposed to sunlight, it may lose much of its carotene. The amount of loss on exposure to sunlight is dependent largely on the tempera- ture during the time the dry hay is exposed, there being no loss at 32° in 8 weeks' time. At 68° to 86°, however, the loss may reach 30 percent. Alfalfa can, there- fore, be stored even in the light during the cold months without loss. When, however, the green material has once become dried and is then kept exposed to hot air, there is a loss of both vitamin A and of digestible protein (1188) (table 8).

TABLE 8.—Effect of excessive drying at various temperatures on the quality of hay

Tem- Caro- Time tene Digest- pe'rT ' Time : ^^¡^; \ Digest- pera- of ex- ible pro- ture per 100 ?ure of ^^- ipSToo'^bl^P^'^- too i oí ^^- iDe?Tooi^^^«P^o- (°F.) posure grams tein (0 F ) I ^^'^'^ grams Î ^em

Min- Milli- Min- Alilli- ; Min- Milli- '■ utes grams Percent utes grams ! Percent Utes • grams Percent 10 25.1 82.9 10 16.8 ; 83.4 320__- 356- 392. 10 7.7 ^ 41.3 60 4.7 46.4 60 2.0 ■■ 27.8 GO .0 9.9 li

Green pasture grass and the same grass after drying at different temperatures has been analyzed with the results shown in table 9 ^^^'^^

TABLE 9.—Chemical composition of fresh and dried pasture grass, on dry basis

I Nitrogen-1 Dry Crude Ether Phos- Condition of grass Protein ! free ex- I Calcium ' matter fiber extract phorus 1 \ tract !

Percent Percent Percent ■ Percent I Percent Percent Percent Green 24.0 16.4 21.5 3.8 46.0 I 0.76 I 0.4S Sun-cured for 18 hours 92.2 18.8 20.5 I 3.5 j 44.6 I .73 .65 Dried at 250° F 92.4 17.5 20.2 I 4.6 I 46.5 .73 .52 Dried at 300° F 92.7 17.8 21.0 \ 5.1 I 43.8 I .76 .56 Dried at 350° F 92.6 18.2 21.0 ' 4.3 ! 44.9 ; .67 ' .52 Dried at 400° F 93.2 18.0 22.9 5.0 i 42.5 1 .69 .58 1000 YEARBOOK OF AGRICULTURE, 1939

McCliire (719) gives equally interesting results after having analyzed green pasture, field-cured hay, and artificially cured hay (table 10).

TABLE 10.—Composition of fresh, field-cured, and artificially dried hay, on water-free basis

N itrogen- Condition of hay Moisture Ether ex- Ash Crude Crude pro- tract fiber tein frec ex- tract

Percent Percent Percent Per ce lit Percent Percent Qre(?n . __ _ 73.0 2.9 9.5 27.6 19.1 40 9 Field cured- . . _ __ ]6.9 2.1 6.9 28.2 13.7 49 1 Artiñcially cured 4.4 2.5 9.1 27.4 18.0 40 ,5

This same author found that drying at a temperature up to 250° F. did not injure the color of the hay, but concludes that artificial drying should not super- sede field curing in locahties where ideal haying conditions prevail. Woodman, Bee, and Griffith {1257) give results showing the coefficient of digestibility of the constituents of freshly cut and of kiln-dried grass (table 11).

TABLE 11.—Coefficients of digestibility of freshly cut and kiln-dried grass

Freshly Kihi- Freshly Kiln- Constituent cut dried Constituent cut dried grasp grass grass grass

Percent Percent Percent Percent Organic matter 79.3 79.4 Carbohydrate ('nitrogen-free Crude protein. . _. : ._. _ 81.3 78.2 extract)_ - 80.3 80 4 Fat ('ether extract) 57. 2 73.7 Crude fiber _ 80.2 81 0

It is concluded that direct heat in a kiln does not depress the coefiicient of digestibility. While the temperature of the inlet gases (which come in contact with the young grass) may be as high as 302° F., the temperature of the grass itself never rises beyond 176°-194° so long as active evaporation of water is taking place. In the use of a band drier, with inlet temperature of 392° F., grass was dried down to 10-percent moisture content in 10 minutes, the amount of digestil:»]e protein being only slightly depressed. When, however, grass was dried in a pneumatic conveyor in 15 seconds at 1,112°, the digestible protein was appreciably decreased {1191). Artificial drying also saves space. Dried, chopped grass, for example, will require only about half the storage space needed for ordinary hay. Young Grass The artificial drying of young grass, or short leafy herbage, before the stemming stage or before the nodes appear is a relatively new idea in the production of hay. Such young grass is extremely rich in protein, fat, minerals, and vitamins. W^hen it is cut weekly, the amount of protein in the grass after being dried may be as high as 21 percent; when cut at intervals of 3 weeks, the protein content will be about 19.3 percent; at 4-week intervals, 17.2 percent; and at 5-week intervals, 14 percent {971). The cutting and drying of young grass to make a concentrated feed is a more urgent problem in England than in the United States. The frequent rains in England also favor the growth of grass. The composition and digestibility of fresh and dried young grass (table 12) have been studied by Watson {1187), the inlet temperature of the drier being 392° F. Drying of young grass apparently does not affect the content of vitamins A, B, G, or D. The carotene is retained almost entirely. If, however, the grass is wilted for 6 hours before artificial drying, as much as 14 percent of the carotene may be lost. Young grass has been found to be effective in giving animals greater powders of resistance against disease. It has been noted, for example, that white scour in calves and udder troubles in cows are less frequent wiien dried young grass is fed {971), LOSSES IN HAY AND SILAGE 1001

TABLE 12.—Composition and digestibility of fresh and dried grass^ on water-free basis

Fresh grass Dried grass Constitaont Composition Digestibility Composition Digestibility

Percent Percent Percent Percent Crude über 21.9 80.4 21.9 78.1 Crude protein 17.6 77.6 17.6 72.6 Carbohydrate (nitrogen-free extract) 44.9 77.5 45.9 77.0 Organic matter 86.5 77.3 88.5 75.7 True protein - - 13.1 70.8 16.9 72.2 Minerals (ash) 13.5 11.5

Instead of merely drying the young grass, so-called grass cakes have been made by first steaming the grass in troughs in order to dry it to less than 10 percent of moisture and then compressing this dried grass with a hydraulic press to a density such that 2,000 pounds occupied a space of 40 cubic feet. This grass cake con- tained 23 percent of protein, or 2}^ times as much as is found in ordinary hay, and retained the original grass color (1^54). The percentage of fiber in dried young grass is less than in hay. Further, the fiber is practically as digestible as that of fresh grass. A yield of S% tons of dried young grass per acre is obtained when cuttings are made monthly. It is claimed that young grass provides more protein per acre than almost any other crop, except possiÍDly marrow-stem kale.^ One hundred pounds of dried young grass contains 13 to 14 pounds of digestible protein and 67 pounds of starch equivalent. A cow giving 5 gallons of milk a day will obtain all the protein, energy, and minerals required by consuming 33 to 34 pounds of dried grass. After having been dried, young grass may be ensiled as well as compressed.

SILAGE The curing or preserving of and grasses by ensiling in order to produce high-quality roughage is not only a source of national wealth but is destined to play a role of paramount importance in the agriculture of the future. Such a product is known as silage. According to one definition {1193) silage is a succulent fodder, made from fresh forage crops by storing them in a stack, trench, pit, or , from which air is excluded as much as possible ; according to another, it is a preserved fodder that has acquired a more or less aromatic odor and an acid taste without putrefactive or moldy flavors {53)] and according to a third, it is moist feed conserved in the absence of air (see The Nutritive Value of Harvested Forages, p. 981). Woodman and Amos {1265) divide silages into five distinct groups: (1) Sweet, dark-brown silage; (2) acid, light-brown silage; (3) green, fruity silage; (4) sour silage; and (5) musty silage. are of more recent origin than granaries. Columbus found that the Indians used pits or trenches to preserve their grain. But antedating that by centuries, Pliny tells of grain being stored in pits, as airtight and air-free as possible, in Greece, Spain, and Africa. Varro, who lived during the second century (116-27) B, C, relates how grain was kept for over 50 years in pits. It is also known that in ancient Egypt silos constructed of masonry were used for preserving grains. In Metz, France, in 1707, there was uncovered a granary containing

3 Daily Digest, U. S. Departmont of Agriculture, May 26, 1936. [Mimeographed.] 1002 YEARBOOK OF AGRICULTURE, 1939 grain that had been stored in 1528 and that was still in such good condition that, it is claimed, good bread was made with flour milled therefrom. Green forage is said to have been preserved during the early history of the Baltic Provinces and in Sweden, where the uncer- tainty of the weather rendered difficult the proper curing of hay (1251). According to Samarani (1008) mention is made by John Symonds (University of Cambridge, 1786), of the ensiling of leaves by the peasants of Italy. The leaves were gathered in the cool of the day, allowed to wilt for 3 to 4 hours in sunlight, placed in wooden tanks that had been partly buried in the soil, compressed, and covered with earth. The tanks themselves were then covered with and more earth. This procedure is quite similar to the Crema process used today and described later in this article. In the course of time the buried tanks were modified into above-ground silos, made of wood, stone, concrete, and other materials. The present-day silos are in general not very different from those in use during the early years of the eighteenth century. In 1875 Goffart, in a paper presented to the Société Centrale d'Agriculture de France (26), related his experience with corn silage. He is reported to have said that at the time he purchased his in 1840, 8 scrawny cows and 120 lived a miserable existence, whereas ^^today the same farm. (300 acres) nourishes abundantly 68 , 6 , and 300 sheep.'' The method of ensiling used at that time was somewhat similar to the American tower process. Ac- cording to Woll (1251), Goffart may justly be called the ''father of modern silage." The first silo built in the United States, also according to Woll, is said to be that erected by F. Morris in Maryland in 1876. With a yearly production of over 60 percent of the world corn output and the consumption of some 40 million tons of silage made chiefly from corn, the United States is justly known as the land of silos. The amoimt of corn silage produced per acre in the United States ranges from 4 to 20 tons. Depending largely on the nature of the crop and the locality, as much as 40 tons of silage (in the case of sun- flowers, for example) may be produced per acre. A corn crop that if allowed to mature would yield 50 bushels of shelled grain to the acre, would produce 8 to 12 tons of silage. A ton of ensiled corn would have yielded on the average only 5 to 5)^ bushels of shelled grain (im). The feed value of corn silage is evident when it is realized that 100 pounds of dry matter contain 4.3 to 4.8 pounds of digestible crude protein and about 40 pounds of total digestible nutrients (521). Though corn is the principal crop utilized for silage in this country, grass silage can be made as advantageously in many places, and sometimes more economically than field-cured hay. Practices in different countries have shown that almost any herba- ceous crops can be used singly or in combination in making satisfac- tory silage. These crops include corn, , and vetch, alfalfa, , and other legumes, timothy and other grasses, sunflower plants, beet tops, leaves and stems, soybean plants, and others. The only crops that do not lend themselves satisfactorily to ensiling are the LOSSES IN HAY AND SILAGE 1003 root crops and those belonging to the Brassicaceae family (cabbage, kale, etc.)- Cured hay deteriorates in feed value, while ensiled grass can be kept a long time with relatively small loss. Further, there is never any loss of ensiled grass as the result of farm fires, whereas 20 percent of the 150 million dollars' worth of farm property destroyed by fire each year is due to spontaneous combustion of stored hay. Grass silage contains about 70 percent of water and will not burn. There is relatively little loss of protein and dry matter—generally not more than one-fourth of the starch-equivalent or one-twentieth of the pro- tein—in good silage compared to the losses of these constituents in haymaking even under favorable weather conditions. Immature grasses, as a rule, make better and more palatable silage than do mature crops. The same applies to the making of hay. The chopping of grasses and legumes increases the amount of material that can be ensiled. Partial drying also increases the amount of dry matter than can be stored in a given space, but it tends to increase the surface spoilage {1267). It is generally admitted that good silage can be made in all types of upright silos if they are airtight. Silos with a gravel or concrete floor and with an open drain generally produce the most uniform silage, although many good silos are not provided with drains {821). Data given by Hosterman {BJi^S) and by Hamlin {Jt-6S) show that the space occupied by silage is approximately 44 cubic feet per ton, as against 470 to 485 cubic feet per ton for stacked alfalfa or 625 to 640 per ton for stacked timothy. Large bales (box-pressed) of hay require about 200 cubic feet per ton, whereas the small or common bale will occupy from 100 to 150 cubic feet. The study of the chemical changes that take place during the ensiling process was first undertaken about 50 years ago. Today a vast and impressive literature confronts the student of this question. In the light of present knowledge—and lack of knowledge—the fol- lowing conclusions would seem to be justified: 1. In making silage it must always be kept in mind that air is enemy No. 1, and that silage which becomes heated consumes itself. 2. Undue or excessive losses are obviated either by the quick development of carbonic acid, as when heavy pressure is used in the Crema process, or by the production of sufficient acid to overcome the ravages of bacteria and other organisms, as in the making of ordinary corn silage. 3. The use of silage made by the addition of mineral acids or by the use of chemical sterilizers has not been proved safe beyond question, in long-time feeding procedure. 4. The use of such chemicals must for some time be looked upon with suspicion and in most cases rejected in favor of the more natural processes. Apparently the best method of supplying materials to the animal (and this refers to the use of phosphoric acid and other acids or chemicals used in making silage) is through the feeding of forages naturally rich in minerals that have been taken up from the soil and metabolized by the plant. 5. It is a question whether silage prepared by the addition of mineral acids can be considered as beneficial to the animal as are silages in 1004 YEARBOOK OF AGRICULTURE, 1939 which the acids of the organic type have been naturally formed. 6. The question whether made by the farmer himself from some of his waste farm products can be economically and suc- cessfully used in silage instead of mineral acids may be w^orthy of study. 7. The vast amount of data, much of it inconclusive, reported by the various workers in this field indicates the necessity for concerted cooperative study of silage questions. For example, what kind of silo should be used under various conditions—with various crops harvested at different stages of growth, in different localities, under different weather conditions, by diñ'erent processes, and with the aid of various added substances, chemical or otherw^ise? 8. The methods of sampling silage for analysis and the basis used for the calculation of results may lead to erroneous conclusions regard- ing the feed value of the silage. These sources of error should be eliminated. 9. The variation in the loss of dry substance resulting from the ensiling of dift'erent crops by different processes is of great economic importance. For example, with a consumption of 40 million tons of silage a year, a loss of 5 percent of dry matter w^ould be equivalent to over 2 million tons of feed and a loss of 15 percent would mean that farmers would have fully 7 million tons less of feed at their command. 10. Practically no information is available regarding the effect of fertilizers, soil treatment, and other factors on the quality of silage produced from the same crop growm in different localities or under differing systems. 11. Little or no information is available regarding the relative effect of added mineral acids and of natural^ formed organic acids on the character and utilizability of the mineral constituents of silage and oí some of the important organic constituents. 12. Under certain favorable conditions the losses in haymaking are- less than in ensiling (^7^, 1256), The silo, however, is a means of saving considerable feed, which, if field-cured under ordinary or un- favorable conditions, would suffer appreciable loss. Silos can be filled in almost any kind of weather. Silage is an emergency feed. 13. Protein-rich crops—that is, crops with a ratio of 1 part of pro- tein to 2 parts or less of carbohydrate—are generally most successfully ensiled if mineral acids or molasses is added (4-^4) • 14. Carbohydrate-rich crops—that is, crops with a ratio of 1 part of protein to more than 2 parts of carbohydrate—can be ensiled without any addition of sugar or acid if they are ensiled in a moist condition.

DATA ON LOSSES AND FEEDING VALUES IN SILAGE Beginnings of Experimental Work In 1883, Weiske and Schulze {1199) made silage experimentally for the purpose of studying some of the changes resulting from the process of ensiling green crops. Subsequently many other scientists, both in this country and abroad, engaged in the study of this question. Grandeau, of France, was one of the first to observe in silage the presence of acetic and lactic acids. At the Pennsylvania Agricultural Experiment Station a stone-basement root cellar was used as a silo; in the course of 3 years' experimentation a loss of 5 to 12 percent of dry matter was noted, chiefly of other than fiber {906). Henry and Woll {508) noted a loss of dry matter of 22 to 24 percent, the largest LOSSES !N HAY AND SILAGE 1005 losses being in carbohydrate (nitrogen-free extract), protein, and fiber. There was a gain in fat (ether extract), an observation that has been corroborated by many workers in this field, making it reasonable to assume that during the ensiling proc- ess some ether-soluble compounds may be produced. These authors furthermore noted a loss in ash, due, it was claimed, to the movement of juices of the green fodder and to diflïision, Armsby {34) and Jordan (596) proved by feeding tests that the process of en- siling caused a loss of nutritive value. Hills (514) and Collier {855) also demon- strated that there was a loss of dry matter, while Babcock and Russell {53) were the first to point out the role played in silage by bacteria. Theory of Silage Formation Russell (994) in 1908 made a very clear and concise explanation of what goes on during the process of making silage, and this has been somewhat further elaborated by Peterson, Hastings, and Fred {918). When green plants are ensiled in an airtight silo, the plant cells continue to function, that is, to respire, producing carbon dioxide with gradual exhaustion of any oxygen that may be present. The sugars are thus consumed in the absence of air or oxygen, complete oxidation being impossible. The intermediate prod- ucts—alcohol and acetic, lactic, and butyric acids (besides carbonic acid and water)—are probably all formed as the result of the activity of enzymes within the cells. Enzymes also act on the proteins to form amino acids, peptides (val- uable protein break-down products), and even . Because water vapor is largely retained, the temperature of the mass in general is raised somewhat, thus causing greater cell activity, but as the fresh material becomes exhausted the cells die, becoming flaccid and causing the mass to settle. At this time the temperature falls somewhat. Coincident with the decreasing activity of the plant cells comes an increase in the activity of bacteria, yeasts, and molds, causing a secondary rise in tempera- ture. Molds, however, cannot grow without air and cease to reproduce as soon as the oxygen has been consumed. Yeasts disappear within a few days, leaving only the bacteria as active agents. According to Watson and Ferguson {1Ï93) the changes during ensiling are of two kinds: (1) Those occurring while the cells are still alive, and (2) those that come into play after the cells are dead, when the activity of micro-organisms sets in. Most of the changes characteristic of silage—for example, the disappearance of sugar and of the less resistant cellulose, the formation of acids, and the break- down of proteins—are the result mainly of the activity of enzymes within the cells—the primary factors in silage fermentation. The changes brought about by bacteria are regarded as being for the most part secondary. Certain workers in this field claim, however, that because are present in such large numbers in silage their chemical activities cannot be disregarded {837). Typical of the products of bacterial activity are , higher fatty acids, humus, and amines (protein decomposition products). The work of Babcock and Russell of Wisconsin {53) who first showed that if bacteria are destroyed and enzymes only remain active in silage there will be no mold formation, no loss of dry matter, and no change in acidity, has been corrob- orated by Russell of England {994) - While proteins may be changed to non- proteins there will be no loss of total nitrogen. Russell's experiments were conducted on a laboratory scale, green being ensiled in bottles. Table 13 shows the results obtained at the end of 5 months. It is evident that in the absence of air the volatile acids are formed by the protoplasm of the living cells, as the result of anaerobic respiration (with little or no oxygen) ; and that the break-down of the protein nitrogen to nonx)rotein nitrogen is a function primarily of the enzymes and secondarily of bacteria, as certain amino acids found in silage are characteristic of bacterial action. The presence of air results in mold formation, musty smell, and freedom from organic acids, the product even becoming alkaline. It might be concluded also that in the presence of air an appreciable quantity of protein may be synthesized from non- protein nitrogenous compounds, as has been noted in stored barnyard manure. According to Esten, Christie, and Mason {336), sugar—which amounts to about 3 to 4 percent in green-cornstalk juice—mostly disappears during fermentation on ensiling, and the percentage of acid found in the silage is about equivalent to the percentage of sugar originally found in the fresh crop. The alcohol formed 1006 YEARBOOK OF AGRICULTURE, 1939 largely disappears also, having been oxidized to through some kind of fermentation by a combination of yeasts and bacteria, both of which are present in large numbers in freshly made silage. The acid bacteria grow until they produce enough acid to inhibit their own growth, when they die, but yeasts are still able to grow in such a medium and continue to convert sugar to alcohol, which in turn is finally oxidized to acetic acid.

TABLE 13.—Eßect of protoplasm, enzymes^ and micro-organisms^ under aerobic and anaerobic conditions, upon the formation, in silage, of volatile acids and ammonia

All air excluded Air present

Living: maize— Maize plus tolu- Maize plus heat at Maize plus silage | Living maize- protoplasm, en- 98° C—spore-forming juice—protoplasm, j protoplasm, en- zymes, and bac- ene—enzymes enzymes, and micro- zymes, and bac- teria active only active organisms only active organisms present teria active

Silage formed. N" o obvious No obvious change. No obvious change. Putrefaction. No mold. change. Little mold. No mold. Much mold. Dry matter lost, 25 No mold. Dry matter lost, 12 Dry matter lost, 25 Dry matter lost, 60 percent. No loss. percent. percent. percent. Mass became acid. No change. No change. ^Tass became acid. ^tass became alka- Acetic and butyric No volatile acids No volatile acids Acetic and butyric line. acids formed. formed. formed. acids formed. No volatile acids Protein changes to Protein changes to No change in x^rotein Protein changes to formed. nonprotein. nonprotein. No loss of nitrogen nonprotein. Nonprotein changes No loss of nitrogen No loss of nitrogen in form of ammo- No loss of nitrogen to protein. in form of ammo- as ammonia. nia. in form of ammo- Much loss of nitro- nia. nia. gen as ammonia.

Among the acids formed, lactic and acetic apirear to have a favorable effect oji the quality of the silage, while , which is the result of imperfect methods of ensiling and of putrefactive processes, injures the silage as a feed. The presence of acid is one of the criteria of good silage. The role of organic acids is as a preservative, for bacteria cannot grow except in a neutral or alkaline (or only slightly acid) medium. If air is kept excluded—that is, if anaerobic conditions arc maintained—the acidity formed in silage during the first 2 weeks is sufficient to check decomposition. Esten, Christie, and Mason {836) regard the process of acid formation in silage as identical to that in the making of sauer- kraut. The amount of acid in silage is from 1 to 2 percent. In a 100-ton silo there are from 2,000 to 3,000 pounds of mixed organic acid. An animal con- suming 40 pounds of silage a day will ingest an amount of acid equal to that in 7 pints of vinegar. Fully 90 percent of the volatile acid found in good silage is acetic; is next in amount. Butyric acid is found only in silage that shows evidence of spoilage. Lactic and acetic acids are always found in silage, irrespective of the kind of silo construction or the type of silage, according to Dox and Neidig The most obvious phenomena in silage making are, therefore, a rise in tem- perature (depending on the conditions under which the silage is made), changes in the color of the silage, the development of acids due to the oxidation of carbo- hydrates during cell respiration in the absence of air, the production of an aromatic odor, and the break-down of the proteins by hydrolysis. Silage from Different Types of Silos Trench Silage Experience has shown that green crops ensiled in trenches—an old method— make one of the cheapest forms of silage, superior to that made in a clamp (pit stack) or ordinary stack. In a pit or trench there is little loss from the molding of silage on the sides of the pit, whereas in a stack this loss is appreciable. The temperature attained in the material ensiled in a pit, owing to the relative com- pactness and the absence of air, is considerably lower than in a stack. The protein of pit silage is hence more digestil)le. In a trench silo, the average loss of digestible crude protein ranges from 0 to 5 percent (in the case of good-quality silage), and the loss of the starch equivalent LOSSES IN HAY AND SILAGE 1007 averages 10 percent. So long as there is an adequate supply of sugar from the material ensiled and the silo is properly- constructed, the formation of butyric acid, even in high-protein material, will be largely prevented. Stack Silage Stack silage, which is probably the oldest form of silage, requires no capital outlay. As prepared, it frequently show^s a loss, from spoiled silage and silage unfit for feed, of nearly 30 percent of the dry matter. About 50 percent of the material in the center of the stack is, however, good sweet silage; the remainder, amounting to 20 percent more, is still edible, though it contains some butyric acid. Comparative tests conducted for 3 years at the Washington Agricultural Experiment Station {521) of silage in silos and in stacks show that while the losses of dry matter from spoilage were about 7 percent in the silo and 10 percent in the stack, the losses from other causes averaged nearly 25 percent in both silo and stack. The greatest losses occurred during the years when the material was ensiled in a wet condition. The recovery of silage, as measured by samples in bags and by total weight in a silo and in a stack is as shown in table 14.

TABLE 14. —Average recovery of feed constituents of si/age

Carbohy- drate Basis Dry Protein Fiber Fat (nitrogen- Ash matter free ; extract)

Total weight: Percent Percent Percent \ Percent Percent Percent Silo - 76 84 83 1 79 69 87 Stack __. 76 75 86 ; 87 65 114 From bags: Silo --- 86 88 92 111 76 89 Stack 78 75 92 1 97 68 91

Clamp Silage What is known as "clamp silage" in England is similar to silage made in the so-called pit stack frequently found in the West, where a is sometimes used to compress the material ensiled. This form of silage requires very little, if any, expense other than that of digging the pit, but it is difficult to make the silage without considerable loss—greater loss, in fact, than there is in most other forms of silage. The wastage on the top and sides may be as high as 25 percent, and the smaller the clamp the greater the loss; hence this form of silage should be made only on a large scale. Further, considerable sour silage is apt to be found at the bottom, owning to the very tight packing of the ensiled material by and cart (the English way) or by tractor. When succulent materials are ensiled and low temperatures are maintained, as often is the case with sour clamp silage, butyric acid, which accompanies putrefactive changes, may develop. Ammonia and other useless or harmful substances may also be produced at the expense of the proteins {1256), The best that can be said of clamp silage is that it is useful in saving green fodder in a succulent form when conditions are un- favorable for haymaking. The trenches used in the United States appear to preserve the silage more effectively than the British clamp silos. In the South- west particularly, trenches are being used to preserve various forage crops. If the trenches are well drained and the material is covered and packed to exclude air, the losses of nutrients may be little if any greater than in tower silos. Tower Silage Green material ensiled in a tower silo is generally chopped into small pieces and blown into the silo. Almost any kind of green crop may be used, although in the United States corn is the principal crop thus ensiled. Study of the transformations that take place in ensiled corn show that in 1 day after the silo is filled, the oxygen is reduced practicalh^ to zero and carbonic acid increased to 45 percent of the silo gas. In 2 days the percentage of carbonic acid is approximately 70. From this point the relative amount of this gas de- creases, so that at the end of 131 days less than 20 percent is left. The moisture 1008 YEARBOOK OF AGRICULTURE, 1939 content, which approximates 65 to 75 percent at the time of filling, remains practically constant during the ensiling process. The acidity of the juice gradually increases (from x)H 5.9 to pH 4.0 or less), and the sugars decrease from over 8 percent to less than 2. At the time of filling, the amount of soluble nitrogen is about 18 percent of the total nitrogen, whereas at the end of fermentation the amount of soluble nitrogen is approximately 45 percent divided about equally between soluble protein and amino acids plus peptides {918). The loss of dry matter in good corn silage is about 10 percent. During the fermentation no trace of hydrogen, methane, or other hydrocarbons (all decompo- sition products of little or no feed value) is ordinarily found. That bacteria play an important role in tlie production of organic acids and alcohol is indicated by the appearance of large numbers at the time of most active fermentation. Bacteria found in silage grow best at a temperature of alDOut 90*^ F. From the stud}' of the process of making ordinary corn silage, Peterson, Fred, and Verhulst {917) concluded that 15 to 20 percent of the pentosans (carbohy- drates of somewhat less feed value than starch) were lost during fermentation at the end of 50 days. Other investigators have shown that as much as 30 percent of the pentosans may be lost, leading to the conclusion that pentosans as well as the ordinary carbohydrates may also })e active in the production of organic acids {994)' When green maize in sappy condition, containing as much as 78 percent of moisture, is ensiled, the loss of dry matter due to respiration and bacterial action is considerably higher—25 percent or more {1256). When corn containing only 12 percent of dry matter was compressed in water- tight vats, it lost about one-fourth of its dry substance; but when it was loosely packed the loss of dry matter was nearly 36 percent in 115 days, while the loss of protein was over 50 percent {1199). Woodman and Amos {1255) found by analyzing samples taken from bags placed at different heights in various silos that the percentage loss (or gain) of constituents varied as follows: Moist material, 1.5 to 11, loss; dry matter, 5.8 to 11.8, loss; organic matter, 6.3 to 12.9, loss; crude protein, 2.0, gain to 12.2, loss; fat (ether extract), 59 to 122, gain; carbohydrate (nitrogen-free extract), 16.2 to 24.9, loss; crude fiber, 0.9, gain to 11.8, loss; minerals (ash), 3.1, gain to 6.8, loss; true protein, 11.8 to 55.3, loss; amides, 60 to 167, gain. The immature crops suffered the greatest hj^drolytic changes in the protein; over 50 percent of the protein was broken down by hydrolysis, and this increased the amides by 150 percent. Experiments conducted by Hansen {4-72), with the American tower silo in connection with such varied crops as vetch fodder, potato leaves and stems, clover, frozen beets, and meadow grass showed losses in dry matter as the result of ensiling as shown in table 15.

TABLE 15.—Losses or gains in Jep.d constituents as the result of ensiling various crops

Potato Frozen Constituent Vetch stems and Clover Meadow leaves beets grass

Percent Percent Percent Percent Percent Weight of fodder -10,9 -17.8 -9.8 -38.8 -25. 5 Dry matter... -30. (3 -29,8 -20. 7 -26. 5 -26, 3 Crude protein. +8.7 -11.9 -22. 3 -33.0 -24.7 Pure protein -29.2 -40.0 -29. 1 -30.0 JSTonprotein -l-]52. 7 +531. 8 +16. 2 +3, 3 Crude fat -31.8 -35. 2 -51.4 -38.8 -45,0 Nitrogen-free extract -46. 7 -46. 5 -20.3 -30.1 -33. 5 Crude flber__ -10. S -14.3 -16.2 -35.6 -10. 5 Pure ash__ -6.7 -22,1 -32. 6 -16.6 -32.0

From these experiments it was concluded that appreciable quantities of feed values were lost from each kind of material—even more than in ordinary hay- making. It was recommended, however, that when good hay cannot be made because of weather conditions, ensiling is worth while on any farm. Much feed can thus be saved that otherwise would be lost. The losses of carbohydrates and of dry matter in different kinds of silage made from oats and vetch ensiled in a tower silo and in a clamp silo were determined by Woodman and Hanley {1260) with the results shown in table 16. LOSSES IN HAY AND SILAGE 1009

TABLE 16.—Loss of dry matter and of carbohydrates in different kinds of silage

Tow sr silo CJanip .silo

Green Acid brown fruity Sour Sweet i

Percent Percent Percent Percent Carbohydrates 14.7 19.1 45. 9 20.5 Dry matter 7.7 11.2 23.4 31.5

A special study of acid-brown silage and of so-called fruity silage was made by Woodman and Amos {1255) ^ who noted the gains or losses of constituents (table 17).

TABLE 17.—Losses or gains of feed constituents in acid-hrown and green fruity si/age

Average oí 8 trials Average of 8 trials 1 i '• Constituent Acid- ! Green Constituent Acid- Green brown '[ fruity brown fruity •îilage 1 silage silage silage

Percent Percent Percent Percent Dry matter -7.7 -11.2 Crude fiber -6.0 -5.5 Crude protein. .0 -8.2 Ash .0 -9.2 Ether extract- .-. .-- +45.0 +52.4 True protein -28.4 -4J.0 Nitrogen-free extract -14.7 -10.1 Amides +96. 0 +85. 3

Silage Made by Different Processes No effort will be made here to cover silage made by all the known processes, but only those prepared by the most widely used or the most approved methods. In some cases the studies have been made with experimental lots of silage in small jars. Other studies have been made in small silos, constructed to simulate large farm silos. It is generally admitted that for the best comparative results indicative of what goes on in practice in a large silo, the amount of silage used in experiments of this kind should be at least 8 to 10 tons. However, results obtained on a small laboratory scale are very useful in arriving at the amount of the various constituents lost during ensiling. The A. I. V. Patented Method The method developed by A. I. Virtanen, Valio, Finland, between 1925 and 1929, consists of adding to the green crop (grass or ) the so-called A. I. V. solution at the rate of about 17 gallons per ton of fresh material. This A. I. V. solution consists of concentrated hydrochloric acid (5 parts) mixed with concen- trated sulfuric acid (1 part), the mixture being diluted with 4 to 5 volumes of water to form what is known by chemists as twice normal strength of acid. The object is to increase the acidity of the green crop as soon as possible (to a pH value of 3.0 to 4.0). Such a degree of acidity suppresses bacterial fermentation as \Yßll as respiration in the cells, thus preventing spoilage of the ensiled crop. With an acidity of pH 4 or below (the lower the number on the pH scale, the greater the acidity) there is little destruction of the proteins or vitamins. Watson and Ferguson {1192) ensiled a mixture of grasses and clover (moisture content 82 percent, dry matter 18 percent), filling the silo to a depth of 24 feet and using some 15 gallons of the dilute (twice normal) mixture of these mineral acids per ton. With pH 3.7 the carotene in the silage amounted to 57 milligrams per 100 grams of dry matter. This is essentially the same amount as is found in green grass, but somewhat more than in even artificially cured hay. In field- cured meadow hay, ae is well known, the amount of carotene is much lower, only about 1 to 3 milligrams (1256), This is good evidence that in properly ensiled grass the vitamin A potency remains high. Somewhat later, Watson {1189) 141394°—39 65 1010 YEARBOOK OF AGRICULTURE, 1939 made seven accurate trials, conducted at Jealott's Hill, with silage prepared by different methods. The results showed that the loss of dry matter by the A. I. V. process was 17.7 percent as against 18.2 percent by the ordinary ensiling method, 16.1 percent in the case of silage with added molasses, and 17.7 percent in silage with added whey. The loss of protein was 3.8 percent in A. I. V. silage, 5.7 per- cent in ordinary silage, and 5.4 percent in silage containing molasses, while with silage containing whey a gain was recorded. These results are at variance with those obtained by Virtanen {1169), whose experiments indicated that A. I. V. silage suffers not over 8-percent loss of ávy matter, in most cases the loss being nearer 3 percent. Recent experiments conducted at the Rowett Institute {569) demonstrate again that there is little if any difference between fresh timothy grass and the same grass ensiled by the A. I. V. process in quantity of dry matter, crude protein, true protein, and soluble protein. The addition of mineral acids to grass lowers the palatability but maintains the high carotene content and preserves the dry matter. The comparative absence of ammonia in A. I. V. silage was recently corroborated by Peterson, Bird, and Beeson {915). Silage Made With Added Molasses While it is perfectly feasible to ensile high-carbohydrate crops successfully because the acids, produced at the expense of the sugars and starch, act as a preservative agent, it is more difficult to ensile a protein-rich, high-moisture crop by the same method without undue loss. In the case of crops with low sugar and starch content, the development of organic acids in sufñcient amounts to act as a preservative is prevented. Hence it has been suggested that when green grass or legumes are to be ensiled, some fermenting material be added. Reed and Fitch (95ê) were the first to add molasses (5 to 10 percent by weight) to alfalfa and to show that alfalfa so treated had a higher degree of acidity than when no molasses was added. The moisture in the crop w^as 60 to 70 percent. Other investigators {850), however, have failed to find that the use of molasses increases the acid content of alfalfa silage, although it does apparently improve the palatability. Woodward (1267) is likewise of the opinion that'^the main advantage of adding molasses to grasses with relatively high moisture content is to improve the palatability of the silage. Swanson and Tague {1113) ensiled alfalfa with molasses, germinated corn, and sound corn, and obtained the best results with molasses. With grasses or some 40 pounds {ZYi gallons) of molasses should be used per ton; with mixed grasses and legumes, 60 pounds (5 gallons); with alfalfa or clover, 80 pounds (7 gallons) ; and with soybeans, 100 pounds (8H gallons). These amounts have been found to answer the p\u*pose and to yield a palatable silage {821). In general, the higher the protein content of the crop, the more molasses should be used. While the losses in silage made with molasses are somewhat greater thaii in that made by the A. I. V. process, the production of silage with mineral acids entails a great deal more labor and delay than does the production of natural fermentation silage {281) y or one to which molasses has been added. Further, the addition of molasses is better adapted to farm routine than is the use of mineral acids {143). Unlike acids, molasses does not injure the concrete or masonry of the silo and is not troublesome to use, and silage made with it does not need ti> be neutralized with ground limestone as is the case when mineral acids are used. Again, silage con- taining molasses is much more palatable than A. I. V. si l'âge. Silage Made With Added Whey When ordinary whey is added as a substitute for molasses to a protein-rich green crop, satisfactory conservation of the silage is not possible. Excellent silage can be made, however, by the use of dry or concentrated whey either alone or inoculated with lactic acid bacteria. Ño greater losses were noted in such silages than were found in silage made either with molasses or bv the A. I. V. method {17). Defu Solution A modification of the A. I. V, process consists in using hydrochloric acid to which was added a small amount of phosphoric acid. One and'one-fourth gallons, LOSSES IN HAY AND SILAGE 1011 or 16 pounds, of a mixture of these acids are diluted with 4 to 5 volumes of water, and this dilute solution is mixed with the green crop at the rate of 10 gallons per ton. When properly used, phosphoric acid makes good silage, causing the formation of lactic acid. Defu acid is said to have a favorable effect on the re- tention by animals of the calcium, phosphorus, and nitrogen present in feeds (46r3). According to Kirsch and Feeder (632) y the use of the Defu solution resulted in a good silage, the loss of dry matter having been cut fully one-half. When this Defu solution (to which a small percentage of sugar was added) was used with pasture grass in an ordinary silo and in a pit (according to the Dutch method), the silage in the silo had lost 20 percent of the protein and 11 percent of the total organic matter at the end of 3}^ months, and that in the pit 68 and 24 percent, respectively. The acid in the pit silage was chiefly butyric, that in the silo chiefly lactic. The acidity of the silo silage expressed as pH'^was 3.7, and that of the pit silage 5.3 (159). The Samarani or Crema Process The Samarani {1003) or so-called Crema method is a low-temperature fer- mentation method developed at the Bacteriological Station at Crema (Lombardy), Italy, and consists in tightly compressing a partly wilted crop (moisture content 35 to 45 percent) in an airtight silo. The top is weighted with a load of 600 to 2,000 pounds per square yard of area, and this, in a way, acts as a seal. The carbon dioxide produced as the result of respiration within the cells of the vegetable tissue displaces the oxygen within a few hours and acts as a preservative. The theory is that if there is no access of air, the ensiled partly wilted crop will not heat and hence not spoil. When corn is ensiled by the American method in too dry a condition, it is often the practice to add water, and this demonstrates how different are the American and Italian theories of ensiling. In the American method the object is to hasten the development of acid in the silage. In the Samarani process every effort is made to prevent fermentation and to keep down the formation of more than a minimum of acidity. The essential factor in the Crema process is the reduction of the moisture content of the crop to a point where bacterial growth is hindered with subsequent control of fermentation, yet at the same time to retain suflricient enzymic activity in the plant cells to consume the oxygen. Whereas the loss of dry matter in silage in open ditches may amount to as much as 40 percent (the loss of dry matter in corn silage in a tower silo is about 10 percent), the loss in Crema silage prepared in sealed silos is much less; there is little loss of sugar and no more than 10 percent of the protein is broken down by hydrolysis. It is being recognized more and more that fermentation and heating of ensiled material should be reduced to a minimum. Heating to 113° F. and over, as in the old style open silo, consumes the sugars and starch and reduces the nutritive value of the protein, calling to mind the old saying ''silages which become heated consume themselves." Sealed silos of the Crema type prevent all undue heating of the mass; there is little acidification and a minimum loss of dry matter or of nutritive value. Toro-Silon The addition of certain sterihzing agents has been proposed for the purpose of inhibiting bacterial fermentation and preventing the break-down of protein by plant enzymes. This treatment of green crops for silage purposes is exemplified by the so-called Toro-Silon process, which consists of adding a mixture of formalde- hyde and sulfurons acid. According to Kirsch and Feeder {6S2), this treatment has no favorable efl'ect on the quality of the silage or the prevention of losses, and these authors consider that it is useless. The Effect of Acidity Some 63 samples of silage, made from grass and forage crops, were tested by Watson and Ferguson (1193) for true protein, volatile bases (such as ammonia), and amino acids, and it was noted that silages with relatively low acidity (greater than pH 4.5) contained a smaller percentage of pure protein and a higher per- centage of ammonia than the same silages with high acidity (less than pH 4.0). In a general way this agrees with the results obtained by other investigators who, 1012 YEARBOOK OF AGRICULTURE, 1939 on the basis of 83 samples, showed that those with a pH value less than 3.5 averaged 5.9 percent ammonia nitrogen, whereas those with a pH value greater than 5.0 contained 27.4 percent of the total nitrogen in the form of ammonia. This represents a definite loss of protein. From a study of the effect of acidity on the presence of organic acids, it appears that silage with high acidity (low pH) averages considerably lower in volatile acids (chiefly acetic acid), but higher in residual acidity (lactic acid). The more lactic acid and the less acetic acid formed in silage, the better the silage as a rule. Butyric acid is, as a rule, not found in silage of high acid content (with pH 4.2 or less). The acidity of silage also materially affects the ratio of volatile to fixed acids. Silages prepared from grass, grass and molasses, and grass and A. I. V. acid were studied b}' Watson and Ferguson {1193), who found that when the acidity was high (less than pH 4), there was three times as much fixed acid (lactic) formed as volatile acid (acetic). When, however, the acidity was low (greater than pH 4.5), there was over twice as much volatile as of fixed acid. In other words, nonvolatile or fixed acids (chiefly lactic) decrease with an increase in pH value and vice versa. This applies in a general way to butyric acid (also volatile) as well, for when the acidity is relatively low (greater than pH 4.5), the amount of this undesirable acid increases appreciably. The figures from experiments conducted by Watson and Ferguson (1193), given in table 18, show the relative amounts of total acetic acid and of total butyric acid under different pH values and in different kinds of silage. It will be noted that a low acidity (high pH value) in silage is correlated with a high percentage of butyric acid.

TABLE 18.—Amount of acetic and butyric acids in silages with different pH values

pH Kind of silage Acetic 1 Butyric Kind of silasie pn Acetic I Butyric value acid : acid value acid _!_ i acid Perce ûf Percent ,; Percent Percent Grass 4.32 0.61 0.11 ;j Grass arai molasses 5.88 0.50 0.39 Do 5.21 .36 1.-12 !l Grass and mineral acld_ 2.48 .25 Grass and molasses.. 3.89 .04 j Do 4.82 .47

Experiments conducted at the experiment station at Gembloux by Piraux, Hacquart, Joassin, and Desmet (9^7) also show that the higher the pH value of silage the more butyric acid it contains. (Table 19.)

TABLE 19.—Amount of butyric acid in silage with different pH values

Butyric Butyric pH acid in Kind of silage Kind of silage pH acid in value fresh value fresh silage silage

Percent ■ j Percent Warm fermentation in towers _ 4.1 0.23 Cold fermentation, plus molasses. 3.9 0.09 Warm fermentation in stacks.. 4.7 .56 ; Silage plus mineral acids . 3.5 I .00 Cold fermentation 4.3 .52 1

Drainage Losses Drainage samples were collected by Godden Ui'5) every 2 hours each day for 20 days—that is, during the period of flow—and, on analysis, 47 to 82 pounds of dry matter were found in each 100 gallons of drainage liquid. The analysis of the dry matter showed it to be composed of 17 to 28 percent of protein, 19 to 23 of ash, 2.3 to 4.3 of lime, 1.3 to 2.2 of phosphoric pentoxide (phosphoric acid), 0.19 to 0.28 of sulfur trióxido, and 0.00 to 2.07 percent of potash. According to this author, drainage causes an appreciable loss of nitrogen and of minerals and hence should be prevented. As losses from ensiled wet crops are largely due to di-ainage, it is advisable to ensile crops so that there will be no drainage of juice or, at most, very little. The most favorable dry-matter content in crops to be ensiled is about 3Ó percent. If LOSSES IN HAY AND SILAGE 1013 more than 70 percent of moisture is found in the crop, it is advisable to allow it to wilt to approximately this moisture content. The drainage juices are composed mostly of organic acids, soluble nitrogenous compounds, potash, calcium, and phosphorus {1256), On the other hand, Blish {129) concluded, as a result of his studies with sun- flow^er silage, that the drainage juices (chiefly with young plants) contain relatively little food constituents, being mostly water. The bottom layers of silage are under a 60- to 100-ton pressure, and this is suiRcient to force the flow of juice. The lower 10 feet of the silo may, as a result, be in a w^aterlogged condition, resulting in considerable spoilage, the silage becom- ing sour and unpalatable. It would seem therefore that the harm done by re- taining the silage juices may be much greater than the small saving that would result from not draining them. General Comparison of Losses by Different Metliods The losses which silage undergoes depend largely on the method of ensiling. Drew, O'Sullivan, and Deasy {281) found 8.4 percent loss of dry matter in a con- crete trench silo and 16 to 23 percent in tower silos. In a study of some 54 silages made from corn and other crops and of the losses of the feed constituents during ensiling, Ragsdale and Turner {945) found the following variations in percentages (losses —, gains +): Dry matter, —2.1 to -18.1; protein, +5.1 to -38.4; fat (ether extract), +49.4 to -20.3; ash, +11.7 to —15.7; carbohydrates (nitrogen-free extract), —5.8 to —22.5; crude fiber, + 6.7 to -14.6. Brouwer, De Ruyter de Wildt, and Dijkstra {158) (table 20) compared the qual- ity of grass silage made (1) by the A. I. V. process, where 6.2 liters of acid were used per 100 kilograms of fresh grass; (2) with 5.4 liters of 20-percent sugar solu- tion per 100 kilograms of grass, equivalent to 1 percent of sugar; (3) with 2.85 liters of A. I. V. acid containing a small amount of sugar; (4) with nothing added; and (5) by the Holland method (ensiling the partially wilted crop in an open ditch 20 inches deep and covered with soil). They found that the A. I. V. silage was superior to all others in having a higher acidity (less than pH 4.0) and smaller amounts of butyric acid (0.12 to 0.27 percent) and of ammonia nitrogen (16 to 22 percent of the total nitrogen), which indicated that the protein break-down was relatively less in this kind of silage.

TABLE 20.—Acid, ammonia, dry matter, and protein content of silages made with and without sugar and acid ^

Some acid, Item A. 1. V. 1 percent of little sugar No addi- Holland sugar added added tions type

Percent Percent Percent Percent Percent 2 0.45 Lactic acid 0. 7-0.12 3 1.70 0.66-1.05 0.15-0.18 0.10-0.81 2L32 Butyric acid . 12-. 27 3.13 .33-30 1.16-1.50 1.13-1. 33 Ammonia nitrogen (as percent of total nitrogen ) 15.8-21..') 21.4-45. 2 24.2-33. 2 46. 2-63.7 49.6-68. 7 Loss of dry matter 21.3 13.1 12.2 21.7 14.4 Loss of crude protein 31.7 25.4 49.4 34.3 Loss of pure protein 52.7 41.8 61.1 44.7 Digestibility coefficient: Of crude protein 57.0 46.0 Of pure protein 31.0 19.0

i Tlie ranges in pH value in each type of silage are: A. I. V., 3.4-4.3; 1 percent of sugar added, 3.8-4.3; some acid, little sugar added, 4.0-4.2; with no additions, 5.0-5.3; and Holland type, 4.7-5.4. 2 Upper part. 3 Lower part. Changes in Acids and Bases In a study of the changes that take place in the content of acid, volatile bases, and dry matter in crops during the process of making silage, Amos and Woodman {21) show the following relative amounts of these constituents before and after ensiling (table 21): 1014 YEARBOOK OF AGRICULTURE, 1939

TABLE 21.—Comparative content of acids, bases, and dry matter in green crops and in silage

Oats and tares Constitueat Green Silage

Cubic centi- Cubic centi- meters 1 meters 1 Volatile organic acids 8 226 Nonvolatile organic acids 285 594 Amino acids 57 400 Volatile bases _.-.._. 18 100 Kilograms Kitograms Dry matter, 1,000

i Of normal solution per kilogram used to render neutral.

These figures indicate a tremendous increase of volatile acids, an increase of over 100 percent in nonvolatile acids, a sevenfold increase in ainino acids, and a fivefold increase in volatile bases (chieñy ammonia), all of which is accompanied by a 12-percent decrease in dry matter. Composition of Silage and Forage It is generally admitted that the main use of the silo, especially with grasses and legumes, is to preserve, for future consumption, feeds that, on account of adverse weather conditions, would sufifer too great loss of feeding value if field- cured. Under ideal conditions of field curing the difference in feed value between hay and silage is not appreciable. Carotene, to be sure, undergoes considerable loss in hay that has been field-cured, while in silage it is preserved almost intact. Woll {1250) showed that corn fodder, field-cured under normal conditions and then stored over the winter, lost 24 percent of the dry matter and 24 of the pro- tein, whereas the same kind of fodder ensiled lost 16 and 17 percent, respectively. The average losses of dry matter in 54 silos compared to losses from 16 shocks of corn fodder were found to be onlv 50 percent as great in the silo as in the shocks {H5). In a study instituted by Amos and Woodman {21) to determine the comparative composition of cured hay and of silage, the results in table 22 were obtained.

TABLE 22.—Comparative composition of and vetch hay and silage (dry basis)

'■ Carbo- Oats and vetch ! hydrates Fiber

I Percent ' Percent Percent Percent \ Percent Green ! 10. S ; 50.2 3.0 28.1 i 7.8 Hay I 13.0 j 45.8 2. 0 29, 0 I 9. 1 Silage ! 12.5 : 45.fi M.3 29,4 : 8.1

1 Includes organic acids. The Kansas Agricultural Experiment Station {9Ö2) reports the results of a very elaborate study of a number of silages made with alfalfa treated with molasses, or to which corn, soybeans, stover, , or combinations of these were added, and compared the composition of these silages when 7 months old with the composi- tion of the green crops when ensiled. The average composition of the silages and ensiled crops calculated upon the dry-matter basis is as given in table 23. Comparative analyses of a number of silages and of the ensiled materials are given in table 24, the data having been obtained from different sources. These figures are of interest in showing that the composition of the finished silage approximates that of the fresh material except in the case of carbohydrate (nitrogen-free extract). LOSSES IN HAY AND SILAGE 1015

TABLE 23.—Average composition of green crops before and after ensiling

Kitrogen- Acidity, Feed Moisture Ashi Protein i Fiber i free ex- Fati on fresh tract 1 basis

Percent Percent Percent Percent Percent Percent \ Percent Crops as ensiled 65.1 12.0 15.5 24.1 43.8 4.0 0.4 Sîîages 7 months old 66.2 13.0 14.8 28.1 40.2 3. 9 1 2. 1 i i Dry basis.

TABLE 24.—Comparative composition {on dry basis) of various green crops and of silage made therefrom

Mois- Protein Ether Fiber ! Nitro- . Kef- Ash Crop or silage iiire (crude) extract (crude) gen-free! Kind of silage I er- extract '

Per- Percent Percent Percent Percent cent Percent Grass 80. Ô 3.0 0.4 5.0 1.7 9.5 A. I. V 043) Grass silage 79.0 3.1 .6 5.5 1.6 9.3 --^--do U4S) Sunflower 78.6 9.3 1.5 30.3 9.9 49.0 Tower {205) Sunflower silage 73.8 10.2 2.8 32.6 10.0 44.5 -----do Sunflower, wet by rain. 68.2 9.6 2.2 33.3 12.7 42.1 do {20Ô) Sunflower silage 73.9 8.2 2.1 38.2 16.0 35.6 .---_do Corn, milk-stage 76.3 8.4 2.2 20.8 7.6 61.0 do {206) Corn silage 75.6 10.2 2.7 22.9 7.9 56.4 do Corn, glazed-stage 62.9 8.1 2.9 16.8 5.1 67.0 do {205) Corn silage 69.5 8.3 2.8 22.5 7.1 69.4 do Sweetclover, bud stage. 66.2 21.2 2.0 29.6 9.2 38.0 ---.do {205) Sweet clover silage 65.2 21.5 3.3 35.7 9.7 29.8 do {205) Sweetclover, full bloom 57.2 19.6 2.1 33.5 8.9 35.8 do {205) Sweetclover silage 67.9 21.4 2.7 32.0 10.0 34.0 do {205) Fresh vetch fodder 67.7 9.8 3.6 23.5 5.9 54.2 -.---do {472) Fresh vetch silage 67.2 15,4 3.6 30.2 7.9 41.6 do Grass 75.4 10.6 1.6 26.7 8.2 63.0 1 Concrete trench i{281, Grass silage 75.5 9.2 3.9 39.0 8.2 39.7 / silo. \282) Grass 79.5 12.5 1.6 24.7 8.4 54.9 Tower {2S1, 282) Grass silage 75.4 12.6 31.0 7.6 45.2 do Sunflower 81.0 8.4 2.6 27. 0 10.0 52.1 do {129) Sunflower silage 3.0 29.7 49.8 do

The percentage of ash and fiber especially, and in many cases of fat also, increase somewhat during the ensiling process owing, as has already been stated, to the greater loss in carbohydrate, or nitrogen-free extract. From data of this kind, however, it is difficult to obtain any real comprehension of the changes that take place during the ensiling process. To do this, the amount of dry matter lost must also be taken into account; that is, the actual weights of the dry matter in both the fresh crops and the silage are the only safe criteria from w^hich losses can be determined. Feed Values of Hay, Silage, and Fresh Crops The nutritive value of feeds, fresh, ensiled, or field-cured (see the article, The Nutritive Value of Harvested Forages, p. 956), is dependent on several factors— yield, palatability, composition, digestibility, and physiological effect upon the animal organism. The coefficient of digestibility of the feed nutrients in the green crop, in silage, and in field-cured hay has been studied by Drew, O'Sullivan, and Deasy {281) ^ who found that good silage is little, if at all, inferior to the green crop. In a recent survey made by the New Jersey and other agricultural experiment stations {821), 214 farmers considered grass silage superior to hay, 63 noted no difference between grass silage and hay, while 13 thought the silage inferior. Incidentally, 154 farmers and feeders considered grass silage equal to corn silage for milk production, 116 believed it superior, and 57 inferior. 1016 YEARBOOK OF AGRICULTURE, 1939

Experiments with oat and vetch silage indicate that it does not differ materially in composition (on the dry basis) from the hay or the fresh crop {1256). In com- paring the feed value of silages, it should be remembered that the moisture content plays a large role. If, for example, one silage has 75 percent of water and another 80, then in all feeding tests 50 pounds of the latter must be used to replace 40 of the former. The role of mineral acids present in fodder on the animal organism has been studied by Crasemann {239)^ wlio concluded that when silage of the A. I. V. type is fed to animals it produces an acid reaction in the system and an increase in the amount of ammonia and of calcium in the urine; that the feeding of such fodder results in an attack upon the base reserves of the animal tissues; and that such acid-containing feeds should be fed only in connection with high-alkaline hay. While there is apparently no loss of carotene or vitamin A during ensiling, Watson and Ferguson {1192) have concluded that A. I. V. silage is not so efficient as hay artificially dried. Further, while A. I. V. grass silage has about the same feed value as natural-fermentation silage, the latter is more convenient for general use {281, 282). The opinion of other investigators is that silage prepared with the aid of mineral acids should not be fed too liberally because of possible harmful effect on the animal organism due to the action of the chlorine and sulfuric acid ions. These ions may likewise act injuriously through manure spread upon soils poor in lime, and hence every attempt should be made to replace mineral acids (4^4)- On the other hand, Davies, Botliam, and Thompson {187) found the loss of starch equivalent by the A. I. V. process to be only 12.8 percent as compared with 24.0 in silage to which molasses was added and 36.2 in ordinary silage. The corre- sponding losses in digestible crude protein w^ere, respectively, 7.8, 21.1, and 38.2 percent, thus indicating the superiority of k. I. V. silage from this standpoint. Furthermore, Virtanen {1169) showed that the nonprotein nitrogen of A, I. V. silage is made up largely of peptides with little ammonia, whereas ordinary silage contains little peptides and considerable ammonia. Hence the feeding value of nonprotein fractions of A, I. V. silage is superior to that of ordinary silage. It was also shown that the amount of calcium and of phosphorus in the blood of cows that had been fed with A. I. V. silage throughout the winter was normal; that the composition of the teeth and bones of animals fed during a long period was essen- tially the same as that of animals living on ordinary winter forage; and that though the acidity of the urine increased appreciably, no significant amount of carbonic acid was found. Virtanen fed a limestone mixture containing one-third dehy- drated soda in connection with A. I. V. silage and noted that cows consuming as nuich as 45 pounds daily of this silage mixture gave birth to healthy calves.