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1968 EC68-217 Selection and Crossbreeding for the Pork Producer Leo Lucas
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Lucas, Leo, "EC68-217 Selection and Crossbreeding for the Pork Producer" (1968). Historical Materials from University of Nebraska- Lincoln Extension. 3860. http://digitalcommons.unl.edu/extensionhist/3860
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SELECTION and CROSSBREEDING lo,. the Po,.k p,.oduce,.
EXTENSION SERVICE UNIVERSITY OF NEBRASKA COLL EGE OF AGRICU LTURE AND HOME E CONOMICS AND U . S . DEPART MENT OF AG RI CU LTURE COOPERATI NG E . F . FROLIK . DEAN J . L. ADAMS. DIRECTOR Selection and Crossbreeding for the Pork Producer By Leo E. Lucast Agricultural Extension Livestock Specialist (Swine)
What Crossbreeding Can Do * Increase size of litter at farro·wing (crossbred sows farrow larger litters) * Increase litter size at ·weaning (livability) * Increase growth rate
What Selection of Superior Performing Parents Can Do * Increase growth rate and efficiency of gain * Increase meatiness
What Selection and Crossbreeding Cannot Do * Overcome poor management * Replace sound nutrition and feeding * Replace good sanitation and disease control
Introduction Crossbreeding vigor increases growth rate and sur vival. The goal of the commercial pro Crossbreeding is rather common 2. I n th e cmssb1·ed sow, hybrid ducer is to produce quality lean place on most Nebraska hog farms. vigor increases fertility, conception pork economically (Fig. 1) . By selec Ninety percent or more of the pigs rate, litter size and survival of pigs. tion of superior breeding stock and marketed today are crossbred in However, crossbreeding will not by crossbreeding, profits can be in one form or another. However, materially increase: creased. This circular discusses pro even with the large amount of l. Feed Efficiency: Feed efficiency cedures necessary for the producer crossbreeding being done, only a is 35% heritable and can be im to receive full benefits from his small percentage of producers are proved by selecting boars with su breeding program. realizing the full benefits. perior records of feed conversion. Three general areas of decisions Crossbreeding is the mating of 2. Meatiness of Pigs: Carcass will determine the effect of breed genetically different lines or breeds. traits are highly heritable and can ing in yo ur herd. These are: The resulting increase in perform be improved by selecting parents I. Breeding program (crossbreed- ance is called hybrid vigo1· or het with superior meatiness. ing). erosis. It is measured as the percent Caution: Crossbreeding swine in 2. Boar selection. superiority of crossbred offspring itself will not make your operation 3. Gilt selection. over the average of their parents. successful. Remember, all phases of Only by making accurate deci Crossbreeding has several advant hog production are necessary £or sions in each area will the full ages over purebreeding, particularly success. Many producers fail with benefit of your breeding program for traits with low heritability esti their crossbreeding program be be obtained. A half-pmgmm is no mates (Table 1): ca use of one of the following fac better than none at all. 1. Jn the individual jJig, hybrid tors:
1 T he author wishes lO acknowledge the help of the Cooperative Extension Services of Jo,,-a State Cniversity and the U niversity of ~'f i nn eso ta for the illustrations used in this circul ar. The cover picture sho \\·ing the Crossbred Gra nd Champion load at the 1965 International a t Chicago is courtesy of Roy B. Keppy, Davenport, lo\\·a. 2 1. No system of crossbreeding. 2. Select inferior breeding stoc.k. 3. Poor choice of breeds.
Systems of Crossbreeding To realize the full benefits from a crossing program, you must fol low a well planned system of breed ing. You may use one of several crossbreeding programs. These pro grams vary in the number of breeds used, or in the rotation of breeds involved. Success with crossbreed ing depends on the superiority of the parent stock regardless of breed. Several systematic crossing pro grams can be used successfully. These include a single cross be tween two breeds, continuous two breed cross and rotational cross of three or more breeds. Generally, a three-breed cross is recommended over other crosses if superior boars of three breeds are available.
Single Cross Between Two Breeds A single cross is made by crossing two breeds. For example, Duroc sows mated to Hampshire boars or Yorkshire sows mated to Poland China boars. 'i'Vhen replacement females are needed, purebreds are either produced by the sows in the herd or are purchased from another breeder. Pigs produced from the single cross exhibit hybrid vigor, but this system does not take advantage of hybrid vigor on sow productivity from crossbred sows. You may par Figure L Three types of pork carcasses from 200-pound hogs shown with the cross-section tially overcome this by selecting of untrimmed loins and hams. From left: Meat Type- 60.4 potmds ham and loin, loin sows for good mothering and milk eye area 6.28 square inches, fat u·im 13 pounds. Meat-Less Type-50.6 pounds ham and loin, loin eye area 2.23 square inches, fat trim 13 pounds. Fat Type-49.8 pounds ham ing ability. and loin, loin eye area 3.44 square inches, fat trim 22 pounds. This system is not ge nera lly recommended for the commercial producer because it requires the Table 1. Heritability Estimates. purchasing of purebred gilts. In the Level of heritability Trait I Average percen t long run, if you select female re I placements from your own herd, High Carcass Length 65 genetic improvement will be made Percent Ham (based on carcass weight) 60 with less risk of introducing· disease Backfat Thickness 50 Loin Eye Size 50 problems. Medium Percent Lean Cuts (based on carcass weight) 35 Feed Efficiency 35 Two-Breed Cross GrO\\'Lh R ate (11·eaning to market) 30 The two-breed cross uses pure Low Weaning Weight 15 bred boars of two different breeds Number farrowed 10 in alternate generations (Fig. 2) . Number weaned 10 Crossbred gilts are selected each Birth "·eight 5 3 1ST YEAR 2N D YEAR JRD YEAR 4TH YEAR lATER YEARS Breed Selection Hampshire and Selection of breeds to be used in Spot boars the crossing program is important. Breeds should be selected to com , X X X X re peat X plement each other in addition to fLirl~ ~ lfLirl~ ~ l seguence using breeds available locally. Crossbred sows Normally, when starting a pro 8 gram, females should be selected from a rapid, efficient gaining breed with superior carcass merit. Poland and When available, superior crossbred Landrace boars females may be used and mated with a boar of a different breed. X X X X repeat X This procedure allows you to ob ~1~ ~~ 1~1~ ~ 1 seguence Cross bred sows tain the hybrid vigor in the pig and from the sow in the first gen Figure 2. Examples o[ how purebred boars are used on crossbred sows in two-breed eration. rotation. To help you select breeds, the breeds have been divided into three generation or year and mated to vantage of more than three breeds groups based on their performance. one of the parent breeds. The boar is the difficulty in finding superior The basis for the division is avail should be selected from the breed performing boars in four or more able performance data. having least relationship to cross breeds. I. Breeds rated high on mother bred females. ing and milking ability; Yorkshire, Under this system, both sows and Specific Three-Breed Cross Landrace, Chester ·white. gilts are crossbred after first cross Some commercial companies 2. Breeds rated high on carcass ing, and will yield more hybrid offer a crossbred female, usually a traits; Hampshire, Poland. vigor in sow production traits than cross of two breeds, and a boar of 3. Breeds rated high on growthi the single cross. Hybrid vigor a third breed for sale. This pro ness; Duroc, Spotted Swine. should result in increased litter gram allows you to obtain hybrid In selecting breeds for a three size, livability and growth rate. vigor in the sow and pig in the first breed cross, one breed should be cross. The system permits the selected from each group if supe Three-Breed Cross breeder to select replacement ani rior performing boars of those The three-breed cross is the most mals on the basis of their specific breeds are available. "When two widely used and recommended sys crossing ability. The producer may breeds are used, you have the choice tem for crossing. This system has wish to continue his crossing pro of selecting a breed from two of the the advantage over two-breeds in gram by selecting replacement gilts three groups. It would not be gen slightly increased vigor for certain from his stock or by returning to erally recommended to select all performance traits (Table 2). How the company for a new group of breeds from one grou p. ever, it is easier sometimes to find gilts and boars after the original top performing boars of two breeds sows fail to maintain high repro How About Hybrid Boars than three. ductive efficiency. Several commercial companies This system uses three different Contrary to the general opinion, offer "hybrid" breeding stock for breeds of boars in rotation on cross crossbreeding programs do not lose sale. Most of these companies have bred gilts and sows produced in the their hybrid vigor. If superior par specific breeding plans to follow. If program (Fig. 3) . It is a continuous ents are selected and a systematic you plan to use hybrid breeding rotation of boars from three breeds. crossbreed program followed, the stock, follow the specific recom Gilts and sows each generation are program can run continuously. mendations of the company. Don't mated to boars of the breed that is Table 2. Performance Traits. least represented in the females. A three-breed cross using superior Percent in crease over purebred performing boars on performance Trait Two-breed cross Three-breed Four·breed between purebreds cross cross selected females is the generally rec Litter Size 0 12 12 ommended program for most pork Number ·weaned 19 20 20 producers. Weaning Weight A three-breed cross may be ex Pig 7 10 II panded to four or more breeds; Liller 2B 40 41 Post TVeaning however, no added hybrid vigor 154 day weight 14 14 14 should be expected over a three Feed Efficiency negligible negligible negligible breed cross. The primary disad- Meatiness 0 0 0 4 1ST YEAR 2ND YEAR 3RD YEAR 4TH YEAR LATER YEARS
Ham pshire, Spot fVi; and Yorks hire boars JJ- ' X X ~ '? Cross bred sows 1 1 l::::::" ~ 1 ~· ~ ~
La ndrace, Poland and Du roc boa rs X
Crossbred sows
Figure 6. Top picture: an approximate Figure 3. Examples of how purebred boars are used on crossbred sows in three-breed 2.90 square inch loin eye area, actual rotation. size. Bottom p icture: an approximately 6.50 square inch loin eye area, actual size. Notice the soft, watery appearance.
Figure 4. Carcass length and backfat Figu re 5. A plainimeter is used to meas thickness measurements. Length is meas ure loin eye area between the l Oth and Figure 7. Weighing ham and loin. Ham ured from the lower point of the aitch 11th ribs after the carcass has chilled a nd loin as a percen t of the chilled car bone to the forward edge o[ the fiHt correctly for 24 hom·s. The loin is cut cass will Yary from 28 percent in extreme rib. Backfat is measured opposite the at an exact right angle and the shon [at type to 44 percent in the YCry out first rib, last rib, and last lwnbar vet·te end of the loin is set on a table with standing meat type. bra. The average of the three backfat the newly exposed loin eye at the top. measurements is used. A piece of acetate paper is then placed over the exposed loin eye and the main Purchasing Boars muscle is u·aced. jumjJ bach and forth fmm hyb1·id i\.Jany prog-rams are available to to pureb1·ed boars and expect to the purebred breeder to aiel him in get good results. Keeping- records more accurate decisions on the se obtaining- information. Breed certi on performance and carcass lean lection and purchase of breeding fication, on the farm testing, test ness and quality will be your best stock. Records should measure stations a n cl ultrasonic measure g-uide for determining- the value of those traits ·which are of economic ments are now used by many breed yo ur prog-ram. value to the pork industry- sow ers. These programs provide i nfor productivity, rate of g-ain, feed effi mation for you to determine which ciency and meatiness. Carcass boar you should select (Table 3). Selection of Breeding Stock length, backfat thickness, percent R ecords identify the geneti c po The key to selection of superior ham and loin, and loin eye area tential of the boar. It g·ives you a breeding- stock is your record of are four of the criteria used to de g-ood idea of what he can or cannot performance and carcass leanness. termine carcass value (Figs. 4, 5, do for yo u. Buying and selecting These records enable you to make 6, 7). your boar each year is probably the Table 3. Suggested Minimum Standards for Selection of Boars. h1ust select the fast gaining meaty Litter Size 7 raised gilts and cull the slow gaining fat Growth Rate 200 to 225 pounds at 5 months ter gilts. The following program is Feed Efficiency Less than 300 lbs. of feed per C\\'t. ga in suggested. For more information, Probed backfat at 200 Jbs. !.0 inches or less contact your county Extension of Nipples 12 or more-none inverted or abnormal Feet and legs sound with good bone fice or write to Animal Science Ex Carcass cut-out of relatives tension, University of Nebraska, a. Ham and loin (percent of ca rc~. ss wt.) 40 % or more Lincoln, Nebraska. b. Backfat · · 1.+ i nchcs or less c. Length '" 29.0 or more inches d . Loin Eye area 4.0, square inches or more At Farrowing Time Ultrasonic Reading of Loin Eye area 4.75' or more square inches l. Identify pigs at birth by ear on individual boar between 190 and 230 pounds notches. Table 4. Suggested Standards for Selecting Replacement Gilts. 2. Record litter birth elate. Litter Size 7 raised At 17 5 to 225 Pounds Growth Rate 175.lbs. and above at5 tnonths l . Make initial selection on gilts Feed Efficiency Less than 325 pounds Probed backfat at 200 lbs. !.4 inches or less; preferably under !.2 from herd on basis of size and inches soundness. Select at least 50% more Nipples 12 or more eve nly spaced, functioned nip· pies than needed. Feet and Legs Sound with good bone 2. 'Neigh gilts accurately and cor Carcass cut-out on relatives Same as boar rect to constant age (Fig. 8). Vltrasonic reading of loin eye area on gilt 4.50 sq. inch or above (190-230 pounds) 3. Probe gilts for backfat and most important decision you make Selectin g Gilts correct to 200 lbs. (Fig. 9.) Your regarding your swine operation. county agent will he! p you probe Don' t be afraid to pay the neces Making the correct decision on your hogs. sary money to buy superior boars; gilt replacement is one of your nec 4. Select g·ilts with low backfat it may be one of the best invest essary jobs to receive full benefit and high gain with visual evidence ments you make. from your breeding program. You of meatiness (Table 4 ).
BACK FAT PROBE ADJUS TMENT CHART 15 4 DAY ADJUSTED WEIGHT CHART 200 LIVE WEIGHT
300 ISO 7 .0
290 155
115 280 160 6 . 5
:=;; 130 250 175 :I:"' ~10 135 ~oo 240 0 5.5 ~qO 180 z ~~0 <{ ~,o vi 140 ID 230 185 ~·0 ..J z ~,o 6 ui ..J 145 ~·0 '!: 220 190 ID 5 . 0 1- ..J ~~0 1- "' ~~0 :I: a: 15 w 210 195 UJ ~,o "'iii 0 1- ..J "' ~oO 3: r 155 "' :::> .. ..J 200 200 0 4 .5 0 iii X :::> "' >'0 170 170 215 1- 175 160 220 3 .5 180 150 225 185 140 230 3 .0 .s 130 235 120 240 U nil~ni"l!" Gf l'f'br:uk..a •":<.ll<'g~ of ''R ri