Nutritive value of Atriplex deserticola and Salicornia forage for ruminants
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Nutritive value of Atriplex deserticola and Salicornia forage for ruminants
De La Llata Coronado, Manuel Maria, M.S.
The University of Arizona, 1991
UMI 300 N. Zeeb Rd. Ann Arbor, MI 48106
1
NUTRITIVE VALUE OF ATRIPLEX DESERTICOLA AND
SALICORNIA FORAGE FOR RUMINANTS
by
Manuel Maria De La Llata Coronado
A Thesis Submitted to the Faculty of the
DEPARTMENT OF ANIMAL SCIENCES In Partial Fulfillment of the Requirements For the Degree of
MASTER OF SCIENCE
In the Graduate College
THE UNIVERSITY OF ARIZONA
19 9 1 2
STATEMENT BY AUTHOR
This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library.
Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Request for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interests of scholarship. In all other instances, however, permission must be obtained by the author.
SIGNED:
APPROVAL BY THESIS DIRECTOR
This thesis has been approved on the date shown below:
R. S. SWINGLE Date Professor of Animal Science 3
ACKNOWLEDGMENTS
I wish to thank Dr. Roy S. Swingle for his guidance, comments, critical reading of this manuscript and friendship that helped me to focus my work more clearly.
I would like to thank Drs. Alejandro R. Urias and William H. Brown for their comments and for being available to discuss my ideas.
My gratitude is also extended to Dr. Jeannette Moore for her cooperation in part of this study. Thanks are also due to the Planetary Design Corporation, Tucson, AZ. for contributing to the financial support of the study and also to Carolyn Watson and Chris Brand from the Environmental Research Laboratory for providing the forages evaluated in this study and background information on their production and on halophytes, in general. I also wish to thank my brothers Antonio, Alejo, Eduardo, Alberto, Pablo and my sister Guadalupe as well as all my friends from the graduate school who either directly or indirectly made the creation of this work possible.
My heartfelt thanks to my fiance Tere Aviles for her patience and support since the beginning of my graduate career.
I am grateful to my parents J. Antonio and Leonor De La Llata for their strong support, advice, love and patience throughout my education, my warmest regards to them. 4
TABLE OF CONTENTS Page LIST OF ILLUSTRATIONS 5
LIST OF TABLES 6
ABSTRACT 7
INTRODUCTION 8
LITERATURE REVIEW 11 General Aspects of Halophytes 11 Feeding Studies with Halophytes 14 Significant Role of salt 16
MATERIAL AND METHODS 19 Experiment 1 - Salicornia 19 Experiment 2 - Atriplex 20 RESULTS 22 Trial 1 - Salicornia 22 Chemical Analysis of Forages 22 Chemical Analysis and Digestibility of Diets . . 24 Trial 2 - Atriplex . 29 Chemical Analysis of Diet Ingredients .... 29 Chemical Analysis And Digestibility of Diets . . 29 DISCUSSION 36 Experiment 1 - Salicornia 36 Experiment 2 - Atriplex 37
APPENDIX A: TABLES 40 Dry matter intake and apparent digestion coefficients for the control diet and for the July, August and September Salicornia diets. Trial 1. . . 41 Intakes and apparent digestibilities of the experimental diets. Trial 2 42 REFERENCES 43 5
LIST OF ILLUSTRATIONS Figure Page
1. Average daily dry matter intake for the control diet and for the July, August and September Salicornia diets. Trial 1 27
2. Dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), crude protein (CP), and gross energy (GE) digestibility for the four experimental diets. Trial 1 28
3. Ad libitum and restricted average daily dry matter intake for the control and Atriplex diets. Trial 2 33
4. Water consumption (ml/lOOg DMI) for the control, Atriplex deserticola and A. barclayana diets. Trial 2 34
5. Dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), gross energy (GE), and crude protein (CP) digestibility for the control and Atriplex deserticola diets. Trial 2 . 35 6
LIST OF TABLES
Table Page
1. Chemical analysis of Salicornia forage harvested at three different cutting dates, alfalfa hay and wheat straw - Trial 1 23
2. Chemical composition of Salicornia diets (July, August and September) and control diet (dry matter basis) - Trial 1 26
3. Chemical composition of ingredients of the experimental diets (dry matter basis) - Trial 2. . . 30
4. Chemical composition of the experimental diets. - Trial 2 31
Al. Dry matter intake and apparent digestion coefficients for the control diet and for the July, August and September Salicornia diets. - Trial 1 41
A2. Intakes and apparent digestibilities of the experimental diets. - Trial 2 39 7 ABSTRACT
Two experiments using lambs were conducted to obtain additional information on the potential nutritional value of halophyte forages for ruminants. In experiment one,
Salicornia bigevolii Torr. planted in mid-March and harvested at three dates (July, August and September) replaced wheat straw (30%) in a 65% forage diet. Nutrient composition and digestibility of Salicornia forage declined with advancing maturity. Forage from the July cutting was superior to wheat straw, while that from later cuttings was approximately equal to straw. In experiment two, digestion coefficients were lower when Atriplex deserticola replaced 50% of the alfalfa hay in a 70% roughage diet. Even when all of the alfalfa hay was replaced using a mixture of 85% Atriplex barclayana and
15% Atriplex deserticola consumption by lambs was not adversely affected. It is concluded that Salicornia bigevolii and Atriplex deserticola have potential as feedstuff for ruminants, especially in geographical areas where conventional feedstuffs are not available. 8
INTRODUCTION
The term halophyte refers to a broad classification of
plants which grow naturally under alkaline or saline conditions. These plants are grazed worldwide by livestock although they are not considered preferred forage species
(Chatterton et al. 1971).
Halophytes represent a promising group of plants for use
as alternative crops in arid lands where water is limited or
of poor quality and for areas where soil salinity limits
productivity of conventional crops. Over a decade ago, the Environmental Research Laboratory at the University of
Arizona began to collect and evaluate halophytes for
potential cultivation under conventional agricultural
practices. Halophytes are being screened for optimal growth
condition and utilization potential. Other uses, such as
management of high saline irrigation drainage water might take advantage of halophyte characteristics. Alternative cropping systems using salt tolerant plants would reduce the
volume of irrigation drainage water requiring ultimate
disposal, by evaporation or other means.
Acceptability and nutritive value of halophytes for
livestock is generally considered to be low (Cook et al,
1959). However, results of laboratory studies conducted at the University of Arizona by the Department of Animal Sciences in cooperation with the Environmental Research Laboratory suggest that some halophyte species have potential as feedstuffs for ruminants.
The high content of ash and sodium chloride in halophytes can reduce palatability (O'Leary 1988), dilute digestible organic matter and adversely affect dry matter intake by livestock. The negative effect of the high salt content may be reduced by blending with other feedstuffs to keep the total salt content of the diet within an acceptable range.
Atriplex and Salicornia are halophyte species native to the southwestern deserts of the United States and northwestern Mexico which have shown promise as potential crops.
Species from the genus Atriplex are among the most studied halophytes. Wiley et al. (1982) showed that 25%
Atriplex lentiformis could be substituted for alfalfa hay in an all roughage diet for goats without adversely affecting diet acceptability or digestibility.
Atriplex deserticola was selected for this study from among several Atriplex species being investigated by the
Environmental Research Laboratory, based on agronomic characteristics and preliminary information on nutrient composition. 10 Salicornia is being investigated as an oilseed crop and as a possible forage (Environmental Research Laboratory,
1989). There is little information on nutritive value of
Salicornia forage and even less on the effect of plant maturity on nutritive potential. This study was conducted to evaluate the vegetative biomass of Atriplex deserticola and Salicornia bigevolii
Torr. and to evaluate the effect of cutting date of
Salicornia on nutritive value of the forage. Results of this investigation will provide information on the nutritional value of halophyte forages and assist in determining their viability as a domestic crops. 11 LITERATURE REVIEW
General Aspects of Halophytes
Producing crops with high saline irrigation water has been accomplished by selecting halophytes with inherently high salinity tolerance rather than by increasing the ability of traditional plants to tolerate high saline water (O'leary et al.1985). Halophytes are capable of acceptable levels of production on salt affected soils on which conventional crops will not grow. The development of salt resistance in conventional crops for such sites would be extremely difficult.
Metabolism and physiology of halophytes are not very well understood, but the cellular basis of salt tolerance in halophytes, as explained by Flowers (1985), is based on the central role of Na+ and Cl" in osmotic adjustments which suggest that the transport of these ions and its regulation must be of primary importance in the physiology of the plant.
Pasternak et al (1986) evaluated agronomic and nutritive characteristics of 120 halophyte species grown under seawater irrigation. Results showed that 26 species performed at least as well under irrigation with 100% seawater as under irrigation with 15% seawater. One outstanding entry was
Atriplex nummularia. When irrigated with 100, 75, or 15% seawater, annual dry matter yields were 1.53, 2.12, and 2.89 12 kg/m2, respectively. Ash and crude protein content ranged from 25 to 40% and from 15 to 21%, respectively. Slenn and O'leary (1985) evaluated productivity of
Atriplex species and Salicornia forage grown in a field trial at Puerto Penasco, Sonora, Mexico using hypersaline (4% TDS) seawater for irrigation. The most productive halophyte species yielded from 1364 to 1794 g of dry weight/m2 annually. When grown using artificial seawater (1% TDS),
Salicornia yielded 1728 g of dry forage/m2. It was concluded that the feasibility of seawater-based agriculture will depend on the selection of desirable crop characteristics in halophytes and developing efficient systems for irrigation with seawater.
Salicornia, an oil seed halophyte, represents a promising crop candidate. This seed crop yields a polyunsaturated vegetable oil that could have value for human use, while the remaining seed meal could be use as a protein feed supplement for livestock (Watson, 1990). Field research studies conducted by Watson et al (1986) with different halophyte species irrigated with brackish water showed that species from the genus Atriplex were the most promising candidates as a multi-clipped forage crops.
Khalil and Sawaya (1986) studied nutritive characteristics of leaves of six Atriplex species grown in
Saudi Arabia. Crude protein, crude fiber and ash contents on 13 a dry matter basis ranged between 16.5 and 25.2%, 7.8 and
10.4%, 18.5 and 27.2% respectively. Atriplex undulata had the lowest and A. nummularia the highest protein and fiber contents. Ash content was lowest in A. canescens and highest
in A. undulata. The level of sodium ranged between 2.58 and
5.57%, except for A. canescens that contained only 0.21%.
These results suggested that Atriplex leaves might have a potential nutritive value for use as a range forage for
livestock.
Watson et al (1987) examined differences and seasonal
changes in the nutrient composition among and within Atriplex
species. Crude protein content of Atriplex lentiformis and Atriplex nummularia decreased and fiber content increased between the first and last harvest dates. Wood (1925) noted that the salt content of halophytes varied seasonally,
increasing in ash toward the end of the dry season.
Moore et al. (1982), screened 45 halophyte species grown
under greenhouse or field conditions and found that in vitro
organic matter disappearance (IVOMD) ranged from 50.1 to
87.2% with a mean of 70.8% and a standard deviation of 8.5%.
In comparison, IVOMD of alfalfa hay was 64.3%. Digestible
organic matter content estimates ranged from 41.1 to 68.4% for the halophyte species, compared with 58.4% for the
alfalfa hay. 14
Feeding Studies with Halophvtes
Atriplex halimus, a shrub widely distributed in Egypt, is characterized by high content of ash and fiber, moderate protein and low energy (El Shaer, 1981). El Shaer (1990) evaluated digestibility of cultivated A. halimus using sheep and goats. Leaves and succulent stems were collected and fed with barley grain supplemented at the rate of 150 grams per head per day. Digestion coefficients for dry matter, crude protein and crude fiber were 65.9 and 64.7%, 60.8 and 60.3%,
62.1 and 66.1% for sheep and goats, respectively. Wiley et al. (1982) evaluated the acceptability and digestibility of Atriplex lentiformis forage using goats.
Atriplex contained more ash than alfalfa hay (27.7 vs 8.1%, respectively). Acid detergent fiber (23.8 vs 37.8%) and gross energy (3.48 vs 4.52 Mcal/kg) were lower in Atriplex than alfalfa hay, while contents of crude protein, cell contents, neutral detergent fiber and lignin were similar for the two forages. Goats readily accepted diets in which 25% of the alfalfa hay was replaced by A. lentiformis, but diets containing 50% or more of Atriplex forage were refused.
Digestibility of crude protein was higher (P<0.05) for the diet containing 25% A. lentiformis than for the alfalfa hay control diet (72.9 vs 64.1%) while acid detergent fiber digestibility was higher (P<0.05) for the alfalfa hay diet
(56.5 vs 48.3%). Digestion coefficients for organic matter, 15 cell contents, neutral detergent fiber and gross energy were similar for both diets.
Utilization of Atriplex nummularia by goats and sheep was evaluated by Kandil and El Shaer (1988). Succulent leaves and stems from A. nummularia harvested at four stages of maturity (early vegetative, winter; full bloom, spring; dough stage, summer and stem cured stage, autumn) were offered ad libitum to mature rams and bucks. Dry matter, crude fiber
increased with advancing maturity. Crude protein and nitrogen
free extract were highest in forage harvested in Spring.
Goats and sheep consumed similar amounts of saltbush. Dry
matter intake was highest for forage harvested in the spring.
Digestion coefficients were higher for winter and spring
forage than for that harvested in summer and autumn. Dry
matter and crude protein digestibilities were similar for sheep and goats but crude fiber digestibility was higher in goats.
Wiley et al. (1982) conducted an experiment in which
Atriplex lentiformis and A. barclayana (untreated or water
leached to reduce salt content) were fed to goats in a diet containing 25% halophyte forage and 75% alfalfa hay. Leaching reduced the ash content of A. lentiformis by about 42% while the ash content in A. barclayana was reduced by 25%. Leaching
of the halophytes did not improve dry matter intake. Water
intake was highest when the diet with untreated forage was 16 fed, (3916 vs 4881 ml/day) and digestibilities for most of the nutrient fractions were higher for the untreated than for the leached A. lentiformis and A. barclayana diets.
MacFarlane et al. (1966) and Wilson (1974) also observed that water consumption by sheep increased as saltbush increased in the diet.
Significant Role of Salt
Because halophytes contain high levels of sodium chloride, it is important to consider the effect of sodium chloride on animal metabolism.
Ingested sodium chloride (salt) by ruminants is almost completely absorbed causing an increase in the blood NaCl which must be eliminated via the urine. Since water is needed to form urine, an increase in salt intake results in increased water consumption. If water is lacking, urine can not be produced and the concentration of salt in the blood increases until it becomes toxic, and sometimes fatal.(Cardon, et al. 1951).
The sodium ion is primarily responsible for toxicity of
NaCl, since sodium acetate or sodium propionate affects animals in a similar manner as sodium chloride. Sodium is excreted mainly through the kidney as sodium chloride or phosphate. Amounts of sodium required to produce toxic 17 effects vary tremendously and are largely dependent on the availability of water to the animals. Mature cows can tolerate more than 450 g NaCl/d without ill effects (Dukes
1977).
Jordan and Hanke (1982) observed that mature ewes in confinement consumed 15 to 30 g/d of salt when it was offered free choice. National Research Council (1980) set the maximum tolerable level of dietary salt for sheep at 9.0%.
Harvey et al (1986) evaluated effects of feeding high levels of sodium chloride (193 grams per day) to growing steers (196 kg initial wt). Total rumen volatile fatty acid concentration was reduced, and turnover rate of liquid in the rumen was increased for the high salt treatments. These effects might be explained by a dilution effect of increased water intake that has been shown to occur in animals fed elevated levels of sodium chloride. Water intake was not quantitated in this study. Passage rate of the solid phase and performance of steers did not differ among treatments.
Kattnig et al. (1991) evaluated the effect of water salinity on digestive function in cattle. High saline water
(2500 ppm TDS) did not affect feed or water intake although there was a tendency for both to be higher than when steers consumed the control water (350 ppm TDS). Steers on high saline water had slower passage and longer rumen retention time for particles. In situ dry matter disappearance was not 18 affected by water salinity, but tended to be higher for the high saline treatment. No clinical or subclinical adverse effects were detected during the study.
Based on agronomic and nutritive characteristics, some halophyte species have potential to be used as a feed source for livestock. The production of alternative crops is currently receiving much attention, especially in areas where conventional crops are not productive. Halophytes represent alternatives to conventional crops for these areas, however the high salt content of these plants could restrict their extensive use as animal feeds. 19 MATERIAL AND METHODS
Experiment 1 - Salicornia
Salicornia forage utilized in this experiment was provided by the Environmental Research laboratory at the
University of Arizona. The forage was from a March planting and three cutting dates (July or immature stage, cut 1; August or seed formation stage, cut 2; and September or mature stage, cut 3) (C.Brand, personal communication). The forage was evaluated in a digestion study with four lambs weighing 53 kg initially. The control diet consisted of 30% wheat straw, 35.2% alfalfa hay, 32.5% steam flaked sorghum grain, 2% dry molasses and .30% NaCl. In treatment diets, wheat straw was totally replaced with Salicornia forage harvested at each of three cutting dates. Lambs were housed in individual pens and fed the diets in a 4x4 Latin square design. Lambs were allowed at least 11 days adaptation between collection periods. Diet samples, feed refusals and total feces were collected for 5 days at the end of each period.
A 10% aliquot of the daily fecal excretion from each lamb was dried for 48 h at 50°C in a forced air oven. At the conclusion of each collection period, dried fecal aliquots were pooled by lamb and ground through a 2 mm screen in a
Wiley mill. A portion of the ground composite was retained 20 for analysis. Samples of diet ingredients and mixed diets were taken during each collection period and prepared for analysis in the same manner as the fecal samples.
Final dry matter, ether extract and ash were determined according to AOAC (1970) methods. Neutral and acid detergent fiber and lignin were determined by the procedures of
Robertson and Van Soest (1981). Crude protein (%N x 6.25) was determined using an autoanalyzer (Technicon). Gross energy was determined using bomb calorimetry. Apparent digestion coefficients were calculated from quantities of each nutrient fraction consumed and excreted in the feces. Analysis of variance for 4x4 Latin square was used for the statistical evaluation of the data (SAS, 1988).
Experiment 2 - ATRIPLEX
Atriplex deserticola provided by the Environmental
Research Laboratory at the University of Arizona was second cutting regrowth cultivated in the San Joaquin Valley (CA) using irrigation drainage water having a high salt content
(electrical conductivity of 18 decisiemens/meter as compared to < 1 decisiemen/meter for fresh water), harvested and baled using conventional forage equipment (C. Watson, personal communication).
Four Suffolk wethers weighing 50 kg initially and housed in individual pens were used in a three-period study. In 21 period 1, lambs were fed the control diet consisting of 70% chopped alfalfa hay, 25% steam-flaked sorghum grain and 5% cane molasses. In period 2, chopped Atriplex deserticola forage replaced one-half of the alfalfa hay. In period 3 all of the alfalfa hay was replaced by Atriplex forage. Because the quantity of A. deserticola was insufficient to complete period 3, the forage used was a mixture of 85% A. barclayana and 15% A. deserticola. The A. barclayana forage was grown and harvested under the same conditions as A. deserticola.
Each period consisted of 21-d of ad libitum intake to evaluate diet acceptability. In periods 1 and 2, the adaptation period was followed by 7-d total fecal collection during which feed intake was restricted to 1600 g of dry matter per day. Fresh water was available at all times during the experiment. Water consumption was measured during collection periods for period 1 and 2 and for the last 7 days of period 3.
Sampling procedures, chemical analysis of diets, diet components and feces, as well as diet digestibilities were determined as described in experiment 1. Statistical analysis was by analysis of variance for a completely randomized design, where sources of variation and degrees of freedom were: lambs,3; diets,2; error,6; and total,11 (SAS, 1988). 22 RESULTS
Trial 1 - Salicornia
Chemical Analysis of Forages
Chemical composition of Salicornia forage at each cutting date is shown in Table 1.
Ash content was 46.0, 42.5 and 34.9% for July, August and September cutting dates, compared with 11.0 and 15.6% in alfalfa hay and wheat straw, respectively.
Cell wall content was higher for Salicornia cut in
September (43.9%) than for that cut in July or August (34.9 and 34.0%, respectively). Cell wall content of alfalfa hay was 45.5% and wheat straw 76.2%, respectively. Acid detergent fiber was 19.8, 16.9 and 22.6% for cuttings 1, 2, and 3, respectively compared to 32.6 and 51.9% for alfalfa hay and wheat straw, respectively. Lignin content of
Salicornia increased with maturity (3.2, 4.0 and 4.9% for forage harvested in July, August and September, respectively). Lignin content for alfalfa and wheat straw was about 6%.
Crude protein values for Salicornia cuttings 1, 2 and 3 were similar (7.9, 8.5 and 7.5%, respectively). Among the forages, crude protein was highest in alfalfa hay (17.4%) and lowest in wheat straw (1.9%). 23
TABLE 1. CHEMICAL ANALYSIS OF SALICORNIA FORAGE HARVESTED AT THREE DIFFERENT CUTTING DATES, ALFALFA HAY AND WHEAT STRAW - TRIAL 1.
Cutting Date Alfalfa Wheat Item July August September Hay Straw
Dry matter, % 91.1 91.6 92.2 92.5 94.0
Composition of DM %
Total ash 46.0 42.5 34.9 11.0 15.6
Cell walls Total 34.9 34.0 43.9 45.5 76.2 Acid detergent fiber 19.8 16.9 22.6 32.6 51.9
Lignin 3.2 4.0 4.9 5.8 5.8
Ash 3.1 1.1 2.6 .4 1.6
Cell contents Total 65.1 66.0 56.1 54.5 23.8
Crude protein 7.9 8.5 7.5 17.4 1.9
Ether extract 1.9 2.0 4.0 3.8 3.7
Ash 42.9 41.4 32.3 10.6 14.0 24 Chemical Analysis and Digestibility of Diets
Because of the high ash content in Salicornia forage, ash content of the experimental diets was higher than the control diet (17.6, 15.0 and 15.5% for cutting dates 1, 2 and 3 respectively vs 9.3% for the control). Neutral detergent fiber was higher for the third cutting Salicornia diet (32.2%) than for the second or first cutting diets (29.3% and
27.9%, respectively). The control diet contained 39.3% neutral detergent fiber. Crude protein content of diets with first, second and third cut Salicornia was 12.1, 12.5 and
11.9%, respectively, compared to 10.9% for the control diet (Table 2).
Dry matter intake (Figure 1) averaged 1332, 1481, 1388 and 1417 g/d for the control diet and for the diets with Salicornia cut in July, August and September, respectively.
Apparent digestibilities (Figure 2 and Table A-l) for dry matter and organic matter were higher (P<0.05) for the cut 1 Salicornia diet (69.6 and 69.3%) than for Salicornia diets cut 2 (65.0 and 66.0%) and cut 3 (65.9 and 64.4%) and also for the control diet (65.5%). Neutral detergent fiber digestibility was similar (P>0.05) for the control diet
(44.2%) and the Salicornia diet cut 1 (44.'5%). Digestibility of neutral detergent fiber for the diets containing cut 2 and
3 Salicornia was 35.6 and 38.9%. 25 Apparent digestibilities of crude protein and gross energy averaged 60.5 and 64.3%, respectively and did not differ (P>0.05) among treatments. 26
TABLE 2. CHEMICAL COMPOSITION OF SALICORNIA DIETS (JULY, AUGUST AND SEPTEMBER) AND CONTROL DIET (DRY MATTER BASIS) - TRIAL 1.
Salicornia Diets Item July August September Control Diet
Dry matter, % 91.3 91.7 91.2 91.3
Composition of Dry Matter
Organic matter, % 82.4 85.0 84.5 90.7
Crude protein, % 12.1 12.5 11.9 10.9 Neutral detergent fiber, % 27.9 29.3 32.2 39.4
Acid detergent fiber, % 19.1 18.6 20.0 28.7 Acid detergent lignin, % 3.3 3.8 2.8 3.2
Ether extract, % 3.2 2.5 4.2 4.5
Gross energy (Mcal/kg) 4.1 4.2 4.2 4.5 1500
5 o> LU 1450- < I- Z DC 1400" Ui
> 1350- tca
1300 —i— CONTROL JULY AUGUST SEPTEMBER
DIETS
FIGURE 1. AVERAGE DAILY DRY MATTER INTAKE FOR THE CONTROL DIET AND FOR THE JULY, AUGUST AND SEPTEMBER SALICORNIA DIETS. TRIAL 1. to 70 U CX3NTFOL H JULY • AUGUST
60- El SEPTEMBER >• H
m H 50- (/> LU g Q 40- Z 111 DC < Q. Q. 30- <
20 A 2 DM OM NDF ADF CP GE CHEMICAL FRACTION
FIGURE 2. DRY MATTER (DM), ORGANIC MATTER (OM), NEUTRAL DETERGENT FIBER (NDF), ACID DETERGENT FIBER (ADF), CRUDE PROTEIN (CP) AND GROSS ENERGY (GE) DIGESTIBILITY FOR THE FOUR EXPERIMENTAL DIETS. TRIAL 1.
to 09 29 Trial 2 - Atriplex
Chemical Analysis of diet Ingredients
Nutrient composition of diet ingredients is shown in Table 3. Atriplex deserticola and A. barclayana contained more ash and neutral detergent fiber than alfalfa hay.
Alfalfa hay contained more crude protein than the Atriplex forages. Gross energy was 4.8, 3.8 and 3.6 Mcal/kg for alfalfa hay, A. deserticola and A. barclayana forage, respectively.
Chemical Analysis and Digestibility of Diets
Chemical composition of the three experimental diets is presented in Table 4. Organic matter content was higher in the control diet than in diets with Atriplex deserticola and
A. barclayana (92.8 vs 87.9 and 82.5%, respectively).
Neutral detergent fiber in A. deserticola and A. barclayana diets (32.1 and 32.6%) was similar. Neutral detergent fiber of the control diet was 29.3%. Crude protein was higher in the control diet (16.4%) than for either the A. deserticola
(13.3%) or A. barclayana (9.0%) diets. TABLE 3. CHEMICAL COMPOSITION OF INGREDIENTS OF THE EXPERIMENTAL DIETS (DRY MATTER BASIS)- TRIAL 2.
Component, Alfalfa hay SF Sorghum A. deserticola A. barclayana grain
Ash, % 9.9 2.1 19.0 24.0
Crude protein, % 18.7 11.2 8.9 8.2
Neutral detergent fiber, % 41.4 12.4 46.2 48.6
Acid detergent fiber, % 29.9 1.8 25.9 26.2
Acid detergent lignin, % 5.9 - 7.2 6.3
Ether extract, % 10.3 3.1 4.3 4.6
Gross energy, Mcal/kg 4.8 4.5 3.8 3.6
u> o 31
TABLE 4. CHEMICAL COMPOSITION OF THE EXPERIMENTAL DIETS0 TRIAL 2.
Component Control15 35% Atriplexc 70% Atriplexd
Organic matter, % 92.8 87.9 82.5 Crude protein, % 16.4 13.3 9.0
Neutral detergent fiber, % 29.3 32.1 32.6 Acid detergent fiber, % 23.9 22.4 18.9 Acid detergent lignin, % 4.2 5.8 4.9
Ether extract, % 4.3 3.8 3.3
Gross energy Mcal/kg 4.7 4.3 3.9
aDry matter basis. bContained 70% alfalfa hay cContained 35% alfalfa hay and 35% A. deserticola dContained 70% Atriplex (85% A. barclayana and 15% A. deserticola) 32 Ad libitum dry matter intake averaged 1732, 1852, and
1718 g/d for the control, 35% Atriplex and 70% Atriplex diets, respectively. Restricted intakes during fecal collection periods averaged 1603 and 1588 g/d for the control and 35% Atriplex diets (Figure 3).
Water consumption (Figure 4) was higher (P<0.05) for the
70% Atriplex diet (758 ml/100 g DMI) than for the 35%
Atriplex diet (484 ml/100 g DMI) and for the control diet
(321 ml/100 g DMI)
Apparent digestion coefficients (Figure 5 and Table A-2) for dry matter, organic matter, neutral detergent fiber and gross energy were higher (P<0.05) for the control diet than for the A. deserticola diet (75.8 vs 71.2, 76.6 vs 70.6%,
54.6 vs 44.6% and 75.2 vs 68.2 Mcal/kg, respectively). Crude protein digestibility (76.9 vs 74.3%) was not different
(P< 0.05) among treatments. 2000 m Ad libitum [Qi Restricted 1750 T3 O) LU 1500 < H Z 1250 DC LU 1000 H H < 750 > DC Q 500
250 0%ATRIPLEX 35%ATRIPLEX 70%ATRIPLEX
DIETS
FIGURE 3. AD LIBITUM AND RESTRICTED AVERAGE DAILY DRY MATTER INTAKE FOR THE CONTROL AND ATRIPLEX DIETS. TRIAL 2. w w 800
700-
600-
500-
400-
300- 0%ATRIPLEX 35%ATRIPLEX 70%ATRIPLEX
DIET
FIGURE 4. WATER CONSUMPTION (ml/lOOg DMI) FOR THE CONTROL, ATRIPLEX DESERTICOLA AND A. BARCLAYANA DIETS. TRIAL 2.
u 80
CONTROL 70 ATRIPLEX
60
o 50 a < 40 5vfls
30
20
10
0 DM OM NDF ADF GE CP CHEMICAL FRACTION
FIGURE 5. DRY MATTER (DM), ORGANIC MATTER (OM), NEUTRAL DETERGENT FIBER (NDF), ACID DETERGENT FIBER (ADF), GROSS ENEGY (GE) AND CRUDE PROTEIN (CP) DIGESTIBILITY FOR THE CONTROL AND ATRIPLEX DESERTICOLA DIETS. TRIAL 2. w ui 36
DISCUSSION
Experiment 1 - Salicornia
Ash content in Salicornia bigevolii forage at the three cutting dates was extremely high (mean = 40.7%) which differs from the ash content found in Salicornia bigevolii (31.5%) by
Glenn et al. (1991). Soil contamination during harvest of
Salicornia, due to the low-growing nature of the plant, could be at least partially responsible for the high ash contents observed. Another interesting observation was that ash content decreased with advancing maturity, in contrast to results reported by Kandil and El Shaer (1988) where ash content of Atriplex nummularia increased with maturity.
Increased fiber content and decreased crude protein content of Salicornia forage with advancing maturity agrees with observations with conventional forages and also in other studies with Atriplex species (Kandil and El Shaer, 1988;
Watson et al. 1987; and El Shaer, 1990).
Diets containing 35% Salicornia bigevolii forage were readily consumed by lambs. In fact, consumption of the
Salicornia diets tended to be higher than the control diet.
O'leary (1988) had indicated that the high content of ash and sodium chloride of halophytes could reduce the acceptability of the Salicornia diets. 37 Even though digestibility of Salicornia diets was higher than (cut 1) or similar to (cut 2 and 3) the control diet, it must be noted that Salicornia forage was substituted for wheat straw, which itself has only a low nutritive value.
Because Salicornia bigevolii can be grown for the oilseed, it would be interesting to evaluate the nutritive value of the straw (crop residue).
In conclusion, results suggest that the nutritional value of Salicornia bigevolii is comparable to that of wheat straw but can be improved slightly if the forage is harvested at an immature stage. Thus, Salicornia forage could be useful in ruminant production in areas of the world in which conventional forages cannot be grown. Because the high ash content dilutes the content of energy yielding nutrients, it is doubtful that Salicornia would be preferred over conventional forages in geographical locations where the latter are available.
Experiment 2 - Atriplex
Ash content for the Atriplex species were within the range (19.0 and 24.0%) reported by others (Wiley et al. 1982,
Pasternak, 1986, and Watson et al, 1987). Crude protein content for the Atriplex species in this experiment was lower than those reported by Wiley et al. (1982) and Pasternak
(1986). 38 The inclusion of 35% or 70% Atriplex forage in the diet did not adversely affect feed intake by lambs, but water consumption increased as percentage of Atriplex in the diet increased. This agrees with results reported by Kandil and El
Shaer (1988) and El Shaer (1981) who also found that feed intake was not affected, but water consumption was increased when diets for sheep and goats contained Atriplex.
Digestion coefficients were lower for the diet containing Atriplex deserticola than for the control diet, which differs from results reported by Wiley et al. (1982).
In that study diet digestibility by goats was increased when
Atriplex was substituted for 25% alfalfa hay in an all roughage diet. The discrepancy between experiments could be due to several factors. Alfalfa hay used in this study was higher quality (higher protein, lower fiber) than that used by Wiley. Atriplex species used by Wiley had higher protein and lower fiber content than those used in this experiment.
The level of Atriplex inclusion was higher in the present study (35 and 70% vs 25%) and the Atriplex species evaluated were different. Also, mixed diets containing grain were evaluated using lambs in this study compared with the all forage diet evaluated with goats by Wiley.
In conclusion, despite the lower diet digestibility when
Atriplex was substituted for alfalfa hay, diet acceptability and the magnitude of the digestion coefficients were 39 sufficiently high to encourage additional research with this and other halophyte species as feed sources for ruminants.
High salt content of halophytes species did not affect intake or digestibility in this experiment or in the one conducted by Glenn et al. (unpublished data). The dilution effect of ash might be reduced by partial replacement with others feedstuffs to reduce the total ash content of the diet. Wiley et al. (1982) and Glenn et al. (unpublished data) showed that leaching Atriplex and Salicornia forages reduced the mineral content but decreased digestibility of the forages. This decrease in digestibility is probably due to loss of cell contents during the leaching process.
In conclusion, Atriplex and Salicornia forages have a potential value as a forage source for ruminants, especially in areas where conventional crops cannot be produced.
However, high ash and fiber content of these halophytes species may restrict their extensive use in livestock diets.
Additional research is needed to define the types of diets and production systems best suited to utilization of halophyte forages. APPENDIX A TABLES TABLE A-l. DRY MATTER INTAKE AND APPARENT DIGESTION COEFFICIENTS FOR THE CONTROL DIET AND FOR THE JULY, AUGUST AND SEPTEMBER SALICORNIA DIETS. - TRIAL 1.
Salicornia diets Item Control diet July August September SEM
Dry matter intake, g/d 1332 1481 1388 1417 61.47
Apparent digestion coefficients, % Dry matter 64.5 69.6 66.0 65.9 1.33
Organic matter 65.5 69.3 66.0 64.4 1.17
Neutral detergent fiber 44.2 44.5 35.6 38.9 2.51
Acid detergent fiber 45.2 45.2 41.4 41.1 2.93
Crude protein 59.4 61.2 59.9 61.7 1.70
Gross energy 64.1 66.8 63.1 63.0 1.32
H TABLE A-2. INTAKES AND APPARENT DIGESTIBILITIES OF THE EXPERIMENTAL DIETS * TRIAL 2.
Item Diets 0% Atriplex 35% Atriplex 70% Atriplex SEM
Dry matter intake®, g/d 1732 1852 1718 81.67
Dry matter intake6, g/d 1603 1588 1570 1.94
Water Intake0, ml/lOOg DMI 321 484 758 28.31
Apparent digestion coefficients, %
Dry matter 75.8 71.2 - .19
Organic matter 76.6 70.6 - .17
Neutral detergent fiber 54.6 44.6 - .36
Acid detergent fiber 60.3 46.5 - .74
Crude protein 76.9 74.3 - .80
Gross energy 75.2 66.8 — .19
aAd libitum (adaptation).
Restricted (collection). cDuring collection. 43
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