Effects of Age of Dam on Weight Traits in the Simmental Population M. A. Elzo, R. L. Quaas and E. J. Pollak

Transcription

1 Effects f Age f Dam n Weight Traits in the Simmental Ppulatin M. A. El, R. L. Quaas and E. J. Pllak J ANIM SCI 187, 64:2-11. The nline ersin f this article, alng with updated infrmatin and serices, is lcated n the Wrld Wide Web at:

2 EFFECTS OF AGE OF DAM ON WEIGHT TRAITS IN THE SIMMENTAL POPULATION 1 M. A. El 2, R. L. Quaas and E. J. Pllak Crnell Uniersity 3 Ithaca, NY ABSTRACT Recrds n birth weight, weaning weight and pstweaning gain frm weaning t yearling frm 83,22 Simmental cales were used t study age-f-dam effects. Estimates f age-f-dam effects were btained simultaneusly with bull effects using a multiple trait ealuatin prcedure. Large age-f-dam effects were fund fr birth weight and fr weaning weight fr yung dams relatie t mature (5- t 8-yr-ld) cws. Age-f-dam effects fr birth weight and weaning weight were smaller in base (nn-simmental) dams than in Simmental dams. Als, age-f-dam effects fr birth weight and weaning weight were smaller fr female cales than fr male cales. Different age-f-dam crrectin factrs shuld be used fr males and females within base and Simmental dams. Agef-dam effects fr pstweaning gain were less imprtant than thse fr birth weight and weaning weight. There was eidence f cmpensatry grwth, especially in cales reared by Simmental dams. (Key Wrds: Age, Grwth, Weight.) Intrductin Bull ealuatins fr weight traits in beef cattle are aimed at btaining expected prgeny differences (EPD) f bulls using field data. The cmputatin f the EPD is based n cmparisns amng unifrm prgeny grups f bulls. Unifrm grups in these data cnsisted f cales being f the same sex, percent Simmental, and brn within a range f d (the definitin f a cntemprary grup). Age-f-dam effects are nt included in the cntemprary grup definitin. Age-f-dam effects are imprtant fr birth weight (Smith et al., 176; Gregry et al., 178; Reynlds et al., 18) and fr weaning weight (Rutledge et al., 171; Smith et al., 176; Gregry et al., 178; Andersn and Willham, 178). Age-f-dam effects might als be imprtant fr pstweaning gain perfrmance (e.g., Yung et al., 178). The American Simmental Assciatin (ASA) until 185 fllwed the Beef Imprement l This research was supprted by a grant frm the Amer. Simmental Assc., Beman, MT. 2 Dept. f Anim. Sci., Uni. f Flrida, Gainesille, Dept. f Anim. Sci. Receied May 28, 186. Accepted Nember 17, 186. Federatin recmmendatins t adjust nly birth weight (BW) and weaning weight (WW) recrds fr age-f-dam effects. The factrs used were additie. Separate factrs were used fr males and females (regardless f percent Simmental) within fur age-f-dam categries: 2 yr f age and yunger, 3 yr f age, 4 yr f age, and 5 yr f age and lder. Hweer, the Simmental data cntains recrds n cales prduced by mating Simmental bulls t nn-simmental females (base dams), 5% Simmental females (F l dams) and 75% and greater Simmental females (Simmental dams). In additin, bulls were used differently depending n the age f dam and the percent Simmental f the female (El et al., 187). Bulls used n heifers and base cws had lwer EPD fr BW, WW, and pstweaning gain (GW) than thse used n cws. Nnrandm usage f bulls t cws based n age r percent Simmental can bias the differences estimated fr these effects unless accunted fr. Cnsequently, the bjecties f this research were t cmpute age-f-dam effects within sex f calf and percent Simmental f dam fr BW, WW, and GW, accunting fr the genetic merit f the sire f the calf. Materials and Methds Birth weight, weaning weight and pstweaning gain infrmatin frm 83,22 Simmental cales brn between 168 and 185 were used 2 J. Anim. Sci :2-11

3 EFFECTS OF DAM ON WEIGHT TRAITS 3 t cmpute age-f-dam effects within sex f calf and percent Simmental f the dam. Data were prided by the ASA. This is the same data set that was used t cmpute the bull ealuatins published in the 186 ASA Sire Selectr. There were 538,32 recrds fr BW, 756,184 recrds fr WW and 141,844 recrds fr GW. The large numbers f bseratins, especially fr BW and WW, allwed the cnstructin f a finer partitin f age-f-dam categries within sex f calf and percent Simmental f dam than thse preiusly used. There were 12 age-f-dam categries. The first ne included 2-yr-ld and yunger females. Categries 2 thrugh 7 were defined by increments f 6 m (e.g., 2 yr t 2.5 yr, 2.5 yr t 3.). Categry 8 cnsisted f cws lder than 5 yr up thrugh 8 yr f age. This categry was defined t be mature cws. Categries t 11 were defined at yearly interals, e.g., categry represented cws lder than 8 yr up t yr f age. Lastly, categry 12 cntained cws lder than 11 yr f age. The age categries were fit within sex-f-calf and percent-simmental-f-dam subclasses. Sexf-calf categries fr BW were males and females. Fr WW and GW, bulls and steers were cnsidered separately. Dams were diided int three grups accrding t their Simmental percentage: base dams (nn-simmental), F 1 dams (5% Simmental) and Simmental dams (greater than r equal t 75% Simmental). The numbers f recrds in each ne f the age-f- dam within sex-f-calf dam-percent-simmental subclass are shwn in table 1 fr BW, table 2 fr WW and table 3 fr GW. Recrds frm female cales accunted fr 63 and 6% f all BW and WW recrds, respectiely, but nly fr 38% f the GW recrds. Male cales represented 37% f the BW recrds, 25% f the WW recrds, and 6% f the GW recrds. Steers cntributed nly 6% f the WW recrds and 3% f the GW recrds. Cnsidering all three traits, cales frm base females had the smallest fractins f recrds (2% fr BW, 34% fr WW, 34% fr GW) and cales frm Simmental females the largest nes (3% fr BW, 34% fr WW, 45% fr GW). Thus, accuracies f the estimates f the age-f-dam effects were n the aerage expected t be greater fr subclasses inling females and Simmental dams fr BW and WW. Fr GW, mre accurate age-f-dam effects were expected fr thse subclasses cntaining males ut f Simmental dams. Age-f-dam effects within sex f calf and percent Simmental f the dam were cmputed tgether with the bull ealuatins fr the 186 ASA Sire Selectr. The prcedure was a multiple trait system (Hendersn, 176; Hendersn and Quaas, 176; Quaas and Pllak, 18) inling BW, WW and GW. Direct and maternal effects were cnsidered as well fr BW and WW. Only direct genetic effects were assumed t be imprtant fr GW. The mdel fr each trait had cntemprary grups, age-f-dam within sex-fcalf percent-simmental-f-dam subclass, ge- TABLE 1. NUMBER OF BIRTH WEIGHT RECORDS BY AGE-OF-DAM PERCENT-SIMMENTAL-OF-DAM X SEX-OF-CALF SUBCLASS Percent Simmental f dam Age f 5 />75 dam, yr Bulls Heifers Bulls Heifers Bulls Heifers ,257,643,23 12, ,77 5,81 7,675 14,77 15,74 22, ,458 3,686 6,781 6,77 1, ,756 1,86 8,83 13,712 12,813 17, ,213 3,448 5,858 5,73 8, ,34 3,6 5,28 4,467 6, ,35 45,234 1,277 27,12 2,123 27, ,13 6,82 2,382 3, , ,765 1,47 2,466 3, > , All ages 45,88 1,75 65,713 15,88 86,71 124,135 %a apereent f recrds within percent Simmental f dam.

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6 6 ELO ET AL. netic grup f sire and f maternal grandsire as fixed effects. The remaining effects, cnsidered randm, were the genetic effects f the sire and the maternal grandsire and residual effects. Sire effects cntained direct genetic effects. Maternal grandsire effects reflected bth direct and maternal effects, except fr GW, which was assumed t represent direct genetic effects nly. Bull genetic grups were btained by first cnsidering the indiidual's pedigree infrmatin [i.e., either, neither r bth his sire and maternal grandsire (MGS) identified] and within pedigree infrmatin by gruping 1 bulls srted by registratin number. The ratinale fr defining grups based n pedigree infrmatin is gien in Pllak and Quaas (181). Gruping by registratin number within pedigree infrmatin attempts t accunt fr trend er time. The definitin f cntemprary grups fr the three traits was the same as that used in preius ASA bull ealuatins (e.g., ASA, 185). Firstly, a cntemprary grup fr BW (BCG) included cales f the same sex and percent Simmental, cming frm the same breeder and brn within d f each ther. Secndly, a cntemprary grup fr WW (WCG) cnsidered all the cnditins specified fr a BCG plus the same preweaning management and the same weaning weight date. Thirdly, a GW cntemprary grup (GCG) required the same pstweaning feeding management and the same yearling weight data, in additin t all the factrs mentined fr a WCG. Thus, GCG were nested within WCG which, in turn, were nested within BGC. Age-f-dam effects were expressed as deiatins frm mature cws (categry 8) within each sex-f-calf percent-simmental-f-dam subclass. There were 72 age-f-dam within sex-f-calf x percent-simmental-f-dam subclasses fr BW and 18 fr WW and GW. As all cales had the sire identified, age-f-dam effects were adjusted fr sire direct genetic effects. Maternal grandsire effects were fitted in the mdel fr all cales haing the maternal grandsire identified. Ninety-eight percent f the cales frm F 1 and Simmental dams had knwn maternal grandsires. On the ther hand, nne f the cales brn ut f base dams had the maternal grandsire identified. As a cnsequence, gien the high percentage f identificatin in F 1 and Simmental dams, their age-f-dam effects were partially adjusted fr the merit f the maternal grandsire. Fr the base cws and fr the ther 2% f cales frm F 1 and Simmental dams with unknwn maternal grandsires, unknwn maternal grandsire grups were fitted. These grups were defined by the year f birth and percent Simmental f calf. There were 11,13 bulls in the data set as either sires r maternal grandsires r bth sire and maternal grandsire. Results and Discussin Age-f-Dam Effects fr Birth Weight. Table 4 shws the age-f-dam effects fr BW fr males and females brn ut f base, F 1 and Simmental dams. Age-f-dam effects fr F 1 dams were similar t thse f Simmental dams; hence, discussin will cnsider nly base s Simmental dams. Age-f-dam effects relatie t mature age (5 t 8 yr) within sex f calf and percent Simmental f the dam were the largest (e.g., -3.4 kg in 75% cws with male prgeny) between heifers and mature cws. The differences decreased as females matured. Age effects past maturity were again negatie. This trend is prbably a reflectin f a greater ability by mature cws t pride the fetus with the necessary nutrients and enirnmental cnditins fr its deelpment. It als suggests a reductin f this ability in cws lder than 8 yr f age. Age-f-dam effects within percent Simmental f the dam were usually larger fr male than fr females cales. In Simmental dams, fr example, the estimates f the age-fdam effects f 2-yr-ld and yunger dams were -3.4 kg fr males and -3.2 kg fr females. This is prbably related t sie f the calf: larger cales require a better uterine enirnment than smaller nes (female cales were, n the aerage, lighter at birth than male cales, table 5). The difference between age-f-dam effects fr males and females tended t disappear as cws reached mature age. Age-f-dam effects within sex were larger fr F 1 and Simmental dams than fr base dams befre they reached mature age. Fr instance, the age-f-dam effects fr 2-yr-ld Simmental and base heifers prducing females cales were -3.2 kg and -2. kg, respectiely. This may be due t a larger difference in sie between yung and mature cws in F: and Simmental dams than in base dams. After mature age, hweer, age-f-dam effects were in general larger fr base dams than fr F 1 and Simmental dams (e.g., the age-f-dam effects n male cales brn ut f 8- t -yr-ld base and Simmental cws were -.2 kg and -.1 kg). This might be an indicatin f an ability f FI and Simmental

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8 8 ELO ET AL. dams t maintain higher prductiity past ur definitin f mature age than f base dams. Hweer, the standard errr f the last fur age-f-dam subclasses (8 t yr ld,..., greater than 11 yr ld) is rather high, especially fr F 1 and Simmental dams. Age-f-Dam Effects fr Weaning Weigbt. Estimates f age-f-dam effects fr weaning weight in base, F t and Simmental females rearing bulls and heifers are presented in table 6. The results btained fr F 1 dams again were similar t thse f Simmental dams. Als, the age-f-dam estimates fr steers within dam percent Simmental were similar t thse cmputed fr bull cales. The patterns f age-f-dam effects fr weaning weight clsely resembled the nes fund fr birth weight. The largest age-f-dam effects relatie t mature age were bsered in 2-yr-ld and yunger dams (e.g., -36. kg fr males frm Simmental dams). The magnitude f these effects decreased almst linearly t maturity (e.g., -2.3 kg fr males ut f 4.5- t 5-yr-l d Simmental dams). After maturity, age-f-dam effects were again negatie, e.g., age effects fr 1- t 11-yr-ld Simmental dams rearing males were 5.1 kg lwer than mature (5- t 8-yr-ld) Simmental dams. Milk prductin f the female has been fund t be ne f the majr factrs affecting weaning weight f the calf (Rutledge et al., 171; Ntter et al., 178; Rbisn et al., 178). Thus, differential milking ability prbably accunted fr mst f the difference in age-f-dam effects between yung and ld cws relatie t mature cws fund in this study. Age-f-dam effects relatie t mature cws fr weaning weight were markedly larger fr females rearing bulls and steers than heifers. The largest differences were bsered in 2-yr-ld and yunger dams (e.g., -36. kg fr males and kg fr females frm Simmental dams). These results indicate that yung and ld cws met the maintenance and preweaning grwth requirements f female cales t a larger extent than thse f males cales (table 6). In additin, age-f-dam effects fr weaning weight were substantially larger in Ft and Simmental dams than in base dams. Fr instance, the age-f-dam effects f 2-yr-ld dams rearing males were -36. kg fr Simmental dams and kg fr base dams. These differences in age effects between base and Simmental dams prbably reflect the higher milk prducing ability f Simmental cws than that f base cws. Base cws were mstly Herefrd and Angus. Research in breed ealuatins has shwn that Herefrd and Angus prduced less milk than Simmental (e.g., Ntter et ~1., 178). The larger age-f-dam effects fund in 2-yr-ld and yunger Simmen tal cws relatie t base cws f the same age indicate that differences in milk prductin between 2-yr-ld and mature Simmental cws are larger than the nes fund in base dams. Age-f-dam effects fr weaning weight after mature age were larger in bulls ut f base dams than F 1 r Simmental dams (e.g., -7.6 kg and -5.1 kg fr bulls frm base and Simmental cws). Fr heifers and steers there were little differences in estimates f age-f-dam effects after maturity (e.g., -5.5 and -6.2 kg fr heifers f base and Simmental females). Age-f-Dam Effects fr Pstweaning Gain. Age-f-dam effects fr pstweaning gain are indirect enirnmental effects. They are a cnsequence f enirnmental effects f a dam n her calf during pregnancy and during the preweaning grwth perid. Hence, if a dam gae her calf an enirnment adequate fr its preweaning grwth ptential, then the calf's pstweaning gain shuld depend nly n its ability t grw. In ther wrds, if a calf grew t its full ptential t weaning, its pstweaning gain wuld be independent f the age f its dam. If the preweaning enirnment prided by the dam was insufficient, a calf may experience pstweaning cmpensatry grwth. Cnersely, if the maternal enirnment was erly abundant these cales may gain less weight in the pstweaning perid than adequately fed cales (e.g., Yung et al., 178). Table 7 cntains the age-f-dam effect fr base and fr Simmental females that reared bulls and heifers. Age-f-dam effects fr pstweaning gain in F 1 females resembled clsely thse f Simmental dams. Als, age-f-dam effects fr steers tended t fllw thse fr bulls. Hweer, they were much mre ariable and had substantially higher standard errrs f estimatin than thse f bulls. Fr example, the effect f 2-yr-ld Simmental dams fr pstweaning gain in bulls was 1.6 kg +.5 kg and in steers was 2.8 kg kg. The age-f-dam effects fr pstweaning gain were slightly psitie fr bulls frm yung Simmental dams. The largest estimate was 1.6 kg fr bulls frm 2-yr-ld and yunger Simmental dams. Fr the base dams, there were three psitie alues nly. They crrespnded t the 2- t 2.5-, 2.5- t 3- and 3- t 3.5-yr-ld dam subclasses (e.g., the 2-t 2.5-yr-ld dam subclass

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11 EFFECTS OF DAM ON WEIGHT TRAITS 11 had a alue f 2.6 kg). The ther yung-cw subclasses were all negatie, e.g, -1 kg fr the 4.5-t 5-yr-ld dam subclasses. Thus, the psitie alues fr sme f the age-f-dam effects fr pstweaning shwed sme small cmpensatry grwth in sme dam subclasses. Hweer, mst f the estimates were clse t er, suggesting that preweaning enirnment was adequate fr the grwth f mst male cales. Female cales, n the ther hand, shwed mre eidence f cmpensatry grwth. Mst f the estimates f age-f-dam effects fr pstweaning gain were psitie fr daughters f Ft and Simmental dams. Yunger cws had larger alues than lder cws, e.g., 4.6 kg and 5. kg fr 2-yr-ld and yunger FI and Simmental dams. The crrespnding estimates fr 4- t 4.5-yr-ld F 1 and Simmentat females were 1.3 kg and 1.5 kg. Age-f-dam effects n daughters f base dams shwed a igagging pattern f psitie and negatie alues frm 2-yr-ld dams t mature cws. Fr instance, the alues fr 2- t 2.5-, 2.5- and 3- and 3-t 3.5-yr-ld base cws were 8.5 kg, -3.2 kg and 3.1 kg. The majrity f the age-f-dam effects fr cws lder than the mature age range was negatie fr male and fr female cales. Fr instance, the estimates fr 8- t -yr-ld dams fr bulls and heifers were -1. kg and.4 kg fr base dams and -1. kg and -1.4 kg fr Simmental dams. This wuld indicate that cales ut f ld dams were erfed during the preweaning perid. Hweer, the standard errrs fr mst f the pstweaning gain estimates f age-f-dam effects are large. Mre data are required t draw firm cnclusins abut pstweaning age-f-dam effects using field data. Cnclusins Imprtant age-f-dam effects were fund fr BW and fr WW in the Simmental ppulatin. Age-f-dam effects were different fr male and female cales and fr base and Simmental females. Thus, if BW and WW recrds were t be adjusted fr age-f-dam effects, separate crrectin factrs shuld be used fr males and females within base and Simmental dams. Age-f-dam effects fr GW were less imprtant than thse fr BW and WW. Als, there was n clear pattern fr these effects in different sexes. Hweer, there was sme eidence fr cmpensatry grwth in cales (especially Simmental females) frm yung dams. Literature Cited Andersn, J. H. and R. L. Willham Weaning weight crrectin factrs frm Angus field data. J. Anim. Sci. 47:124. ASA Sire Selectr. Amer. Simmental Assc., Beman, MT. El, M. A., E. J. Pllak and R. L. Quaas Genetic trends due t bull selectin and differential usage in the Simmental ppulatin. J. Anita. Sci. 64:83. Gregry, K. E., L. V. Cundiff, G. M. Smith, D. B. Laster and H. A. Fithugh, Jr Characteriatin f bilgical types f cattle - cycle II: I. Birth and weaning traits. J. Anim. Sci. 47:122. Hendersn, C. R Multiple trait sire ealuatin using the relatinship matrix. J. Dairy Sci. 5:76. Hendersn, C. R. and R. L. Quaas Multiple trait ealuatin using relaties' recrds. J. Anim. Sci. 43:1188. Ntter, D. R., L. V. Cundiff, G. M. Smith, D. B. Laster and K. E. Gregry Characteriatin f bilgical types f cattle. VII. Milk prductin in yung cws and transmitted and maternal effects n preweaning grwth f prgeny. J. Anita. Sci. 46: 8. PUak E. J. and R. L. Quaas Definitin f grup effects in sire ealuatin mdels. J. Dairy Sci. 66:153. Quaas, R. L. and E. J. Pllak. 18. Mixed mdel methdlgy fr farm and ranch beef cattle testing prgrams. J. Anita. Sci. 51:1277. Reynlds, W. L., T. M. DeRwen, S. Min and K. L. Knce. 18. Factrs influencing gestatin length, birth weight and calf surial f Angus, ebu and ebu crss beef cattle. J. Anita. Sci. 51:86. Rbisn, O. W., M.K.M. Yusuff, and E. U. Dillard Milk prductin in Herefrd cws. I. Means and crrelatins. J. Anita. Sci. 47:131. Rutledge, J. J., O. W. Rbisn, W. T. Ahlschwede and L. E. Legates Milk yield and its influence n 25-day weight f beef cales. J. Anita. Sci. 33:563. Smith, G. M., D. B. Laster and K. E. Gregry Characteriatin f bilgical types f cattle. I. Dystcia and preweaning grwth. J. Anita. Sci. 43:27. Yung, L. D., L. V. Cundiff, J. D. Cruse, G. M. Smith and K. E. Gregry Characteriatin f bilgical types f cattle. VIII. Pstweaning grwth and carcass traits f three-way crss steers. J. Anita. Sci. 46:1178.