CROSSING ANGUS AND MILKING SHORTHORN CATTLE: FEEDLOT PERFORMANCE OF STEERS I,2

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1 CROSSING ANGUS AND ILKING SHORTHORN CATTLE: FEEDLOT PERFORANCE OF STEERS I,2 K. J. Drewry, S. P. Becker, T. G. artin and L. A. Nelson Purdue University, West l.afayette, IN SUARY Evaluation of straightbred and crossbred perforance and estiates of heterosis using 226 straightbred and reciprocal crossbred stecrs fro Angus (A) and ilking Shorthorn (S) cows born over a 5-year period, were obtained for steer daily gain. Steers were weaned at days and iediately placed in thc feedlot by breedtype (A A, A S, S A, S S). Steers were full-fed for 196 days. Weights and daily gains were obtained at 28-day intervals. Steers fro S sires had greater period gains and overall test daily gain than steers fro A sires, except in period 4. Significant breed-ofsire differences were observed only for period 2, period 7 and test daily gain. Adjustent of daily gain for variation in initial weight reduced the sire-breed differences by 3.6%, 1.5% and 5.8%, respectively, for periods 2, 7 and test. Steers fro S darns had greater daily gains than steers fro A das. These differences, kilogras/day, were significant for pcriods 2, 3, 6 and test. Adjustent of daily gains for variation in initial weight reduced the breedof-da difference by 25.4%, 46.7%, 15.6% and 23.9%, respectively, for periods 2, 3, 6 and test. Negative heterosis estiates were observed for daily gain in periods 1 and 2, and positive heterosis estiates were observed in periods 3 to 7 and test. Significant heterosis for daily gain was observed only in periods 3, 4, 6 and test with values (kilogras/day and %) of.15 (12.7%),.10 (9.2%),.11 (11.1%)and.05 (4.1%), respectively. Adjustent of daily gains for variation in initial weight tended to decrease the heterosis estiates for daily gains. Journal Paper No. 7141, Purdue University Agricultural Experient Station. 2 Data derived fro the Purdue University contributing project to NC-1 regional project, Iproveent of Beef Cattle through Breeding ethods. Reciprocal contrasts (A x S vs S x A) were evaluated and found nonsignificant for both actual and adjusted daily gains. (Key Words: Ileterosis, Daily Gain, Angus, ilking Shorthorn.) INTRODUCTION An increased interest in beef cattle crossbreeding occurred in the United States in the early to id 1960's. This interest was brought about by (1) increased production cost, (2) increased efficiency of crossbred (British British, Brahan British) cows copared to straightbred cows for the cow-calf producer, and (3) increased preweaning and postweaning growth rate and increased carcass cutability of Charolais crossbred cattle. As indicated by Cundiff (1970) several dairy breeds are receiving increased attention as prospects for crossbreeding in coercial beef production. The purpose of this study was to evaluate perforance and easure heterosis for postweaning daily gain by coparing straightbred and reciprocal crossbred steers fro Angus (A) and ilking Shorthorn (S) cows. ATERIALS AND ETHODS Data for this study were collected at the Feldun-Purdue Agricultural Center in southern Indiana. Data included postweaning daily gain records for 226 straightbred and crossbred steers. The distribution by breedtype (sire breed given first) was: A A, 53; A S, 56; S A, 55;and S S, 62. The steers were born in October through Deceber during 1966 to 1970, and were weaned at days of age. This resulted in three weaning groups each year, designated as early, iddle and late. Steers were placed in feedlot pens by breedtype as they were weaned (one pen/breedtype/year) during ay, June and July. Pens were solid concrete approxiately 5 x 17, with a sheltered area of 5 x 8 eters. At 313 JOURNAL OF ANIAL SCIENCE, Vol. 48, No. 2, 1979

2 314 DREWRY ET AL. axiu capacity, following weaning of late group steers each year, the area per steer was 7.5 square eters, 3.5 undercover and 4.0 in the open. Average weaning weight (kg) by breedtype was: A x A, , A S, ; S x A, ; and S x S, Steers were fed an ad libitu ration of six parts crushed ear corn (Corn, ears, grnd, Ref. no ) and one part Purdue Suppleent A (artin et al., 1977) over the 196-day feeding period. Weights were taken at 28- day intervals. Daily gain records were obtained on all steers for each of the seven 28-day periods, and for the 196-day feeding period. Analysis. All data were analysed by the ethod of least-squares for unequal subclass nubers (Harvey, 1960). Two odels were used for the analysis of daily gain variable (seven, 28-day periods and total test-196 days). odel 1 included ain effects of years (Y), weaning group (G), sire breed (S), da breed (D), and all two-way interactions as fixed, independent variables. The S x D interaction was used as a easure of heterosis. odel 2 included ain effects of year (Y), weaning group (G) and breedtype (B), and all two-way interaction as fixed, independent variables. The breedtype constants, with appropriate variance and covariance values fro inverse eleents of the least-squares analysis, were used in calculating selected linear contrasts with standard errors for: sire breed (A-S), da breed (A-S), heterosis (straightbredspurebreds) and reciprocal (A S -- S x A) crosses. Additional analyses were perfored for daily gain traits using odels 1 and 2, with steer weaning (initial) weight included as a linear covariate. RESULTS AND DISCUSSION ean squares fro the analysis of actual period and test daily gains using odel 1 are presented in table 1. Adjustent of period and test daily gains for initial weight, by including initial weight as linear covariate in odel 1, gave siilar results to those presented in table 1. Year and~or Weaning Group Effects. Year, weaning group and year x weaning group interaction were significant sources of variation for ost of the period and test actual daily gains (tables 1 and 2). The year weaning group eans for period and test daily gains, not given, showed that for test daily gain superior perforance was observed with steers in the early weaning group in 1967, 1968 and 1969 and for steers in the late and iddle weaning groups, respectively, in 1966 and No consistent trends were observed with the year weaning group eans for period 1 through 7 daily gains. Interaction Effects for Daily Gain. Only six significant two-way interactions, other than the year x weaning group and the sire breed x da breed interactions, were observed (table 1). The year sire breed interaction was significant for period 4. During period 4, S-sired steers had gain advantages of.16 and.13 kg/day, respectively, in 1966 and 1967; with A-sired steers having gain advantages of.09,.19 and.27 kg/day, respectively, in 1968, 1969 and The weaning group x sire breed interaction was also significant for period 4. In early and iddle weaning groups A-sired steers exhibited gain advantages of.27 and.02 kg/day and in the late weaning group S-sired steers had an average gain advantage of.11 kg/day. The year da breed interaction was significant for period 4 and period 6. Differences by da breed (A--S) by year (1966 through 1970), respectively, were:.24, -.24,.02, -.06 and -.36 kg/day for period 4, and -.18, -.17,.03,.08 and -.18 kg/day for period 6. The weaning group da breed interaction was significant for period 1 and period 3. During period 1, steers fro A das in the early and late weaning groups had gain advantages of.09 and.05 kg/day, with steers fro S das exhibiting an average advantage of.14 kg/day in the iddle weaning group. For period 3, steers in the early and late weaning groups fro S das had an average gain advantage of.45 and.02 kg/day and in the iddle weaning group steers fro A das had gain advantages of.08 kg/day. Sire Breed Effects. The A-S sire breed contrasts (table 3) showed that steers fro S sires gained faster than steers fro A sires except in period 4. The advantage for S sired steers was.052 kg/day for test daily gain and ranged fro.007 to.168 kg/day for various periods. However, significant sire breed effects were observed for only period 2, period 7 and test daily gain. With actual daily gain (table 3), steers fro S sires had advantages (kg/day) over steers fro A sires of , and , respectively for period 2,

3 ANGUS AND ILKING SHORTHORN CROSSBREDS 315 TABLE 1. EAN SQUARES FOR PERIOD AND TEST ACTUAL DALLY GAIN (KILOGRAS/DAY) Period a Source df Test Year (Y) Weaning group (G) Sire breed (S) Da breed (D) YXG YXS Y G G S Db Error "* 1.402"*.607**.717"*.689**.927**.954"*,.168"* "* ** 1.965"* 2.469** 2.287** 1.115"* "* *.062* "*.757** ** ** 8.608**.559**.526** 2.731"* 1.208"* 1.384"* 1.342"*.046** * ** " "* " ** ** * " "*.015 aperiods were 28 days each. ban indicator of heterosis. * P.05 and **P.01 describe statistical significance of effects. period 7 and test. Adjustent of period and test daily gains for variation in initial weight by linear regression (table 3) decreased the A--S sire breed contrasts by 3.6%, 1.5% and 5.8%, respectively, for period 2, period 7 and test. Da Breed Effects. Steers fro S das had greater daily gains than steers fro A das (table 3). The advantage for steers fro S das was kg/day for actual test daily gain and kg/day for adjusted test daily gain. With actual daily gain, significant da breed differences (A--S da breed contrasts, table 3) were (kg/day) , and , respectively, for periods 2, 3 and 6. Adjustent for variations in initial weight decreased the size of the breed-of-da difference by 25.4%, 46.7%, 15.6% and 23.9%, respectively, for daily gains during periods 2, 3, 6 and test. Heterosis Estiates. Significant sire breed x da breed interactions, an indication of heterosis, were observed for test and period 3, 4 and 6 actual daily gains (table 1). Estiates of heterosis, with standard errors (crossbred inus straightbred contrasts) for both actual and adjusted period and test daily gains, are presented in table 4. Negative heterosis estiates were observed for daily gain in periods 1 and 2 and positive heterosis estiates were observed for test daily gain and daily gain in periods 3 through 7. Significant heterosis was observed only for period 3, 4, 6 and test actual and adjusted daily gain. With actual daily gain, the heterosis estiates (kilogras/day) were (12.66%), (9.22%), (11.1%) and (4.11%) respectively, for periods 3, 4, 6 and test. The heterosis estiates (kilogras/day) for daily gain, adjusted for variation in initial weight were: (9.40%), (9.68%), (9.95%) and (3.64%), respectively, for periods 3, 4, 6 and test. Adjustent of daily gains for variation in initial weight resulted in lower heterosis estiates for all daily gains except those in period 4. Percent heterosis for postweaning daily gain has ranged fro 0 to 28.3% (Chapan et al., 1971; Gregory et al., 1966a,b; Jain et al., 1971; Long and Gregory, 1975; Pahnish et al., 1971; Sith et al., 1976; Vogt et al., 1967). These studies included variations in breeds and breedtypes, age (14 to 27 onths), sex (heifers and steers), nutrition-anageent progras (pasture feeding vs drylot feeding, and fullfeeding rs deferred-feeding). In general, larger heterosis estiates have been observed for cattle placed on full feed for 150 to 200 days iediately after weaning at 210 to 240 days of age (Jain et al., 1971; Klosteran et al., 1968; Lasley et al., 1973; Long and Gregory, 1975; Vogt et al., 1967). Percent heterosis for actual and adjusted test daily gain of 4.11 and 3.64, respectively, observed with the present study agree with the average advantage of 4% for crossbreds over purebreds in postweaning perforance reported by Cundiff (1970), Kincaid (1962) and Warwick

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5 ANGUS AND ILKING SHORTHORN C ROSSBREDS 317 TABLE 3. SIRE BREED AND DA BREED CONTRASTS FOR DAILY GAIN (KILOGRAS/DAY) Sires (A-S) Das (A-S) Tie Actual Adjusted a Actual Adjusted a Period , Period ** ** ** ** Period , * Period , Period Period ** " Period ** "* Test "* "* "* "* adaily gain adjusted for variation in initial weight by linear regression, odel 2. *P.05 and **P.01 describe statistical significance of contrasts. (1968). Heterosis values in the current study are greater than heterosis for 180-day postweaning daily gain observed by Sith et al. (1976) with straightbred and crossbred Angus and Hereford steers. However, heterosis values in this study are siilar to those for postweaning daily gain observed for straightbred and crossbred Angus, Hereford and Shorthorn steers (Gregory et al., 1966b) and heifers (Vogt et al., 1967), with cattle placed on full-feed at weaning. The present values are lower than heterosis estiates for postweaning daily gain observed by Klosteran et al. (1968), Jain et al. (1971) and Lasley et al. (1973) with studies involving the Angus, Hereford and Charolais breeds with cattle full-fed iediately following weaning. Heterosis for postweaning daily gain does change with duration on test, according to this study. Heterosis values, siilar to those reported for daily gain in the seven, 28-day periods of the present study, were not reported in any of the earlier referenced crossbreeding studies. None of the steers were creep-fed prior to weaning. Average daily gain (kilogras/day), by breedtype, during the last 90 days of the suckling period was: A x A,.77; A x S,.89; S x A,.83 and S x S,.83 (Drewry et al., 1978). The negative, nonsignificant heterosis values for daily gains in periods 1 and 2 were not expected. Negative heterosis is possible only if the straightbred steers had greater average daily gains than the crossbred steers. A possible explanation for these negative heterosis estiates is that the straightbred steers were receiving less ilk prior to weaning and did adjust sooner following weaning and started eating earlier than the crossbred steers. Kincaid (1962) suggested, with straightbred das nursing straightbred or crossbred calves, that part of the increased gains of crossbred calves was due to increased ilk produced by the straightbred da. In the present study crossbred calves nursing A and S cows gained an average of.06 kilogras/day ore than straightbred steers during the last 90 days of the suckling period. The actual period daily gain for each breedtype was expressed as a percentage of its preweaning (last 90 days of suckling period) daily gain. During periods 1 and 2 straightbred steers had 16% and 17%, respectively, larger percent relative gains than crossbred steers. In periods 3, 4 and 6, the periods in which significant heterosis values were observed, the crossbreds exhibited advantages for percent relative gain over straightbreds of 7%, 2% and 4%, TABLE 4. HETEROSIS ESTIATES (CROSSBRED- STRAIGHTBRED CONTRASTS) AND STANDARD ERRORS, AND PERCENT FOR ACTUAL AND ADJUSTED DALLY GAIN (KILOGRAS/DAY) Actual Adjusted Tie Estiate % Estiate % Period : Period Period ** " 9.40 Period * * 9.68 Period Period * * 9.95 Period Test * " 3.64 *P.05 and **P.OI describe statistical significance of estiates.

6 318 DREWRY ET AL. TABLE 5. RECIPROCAL CROSS (A X S--S A) CONTRASTS AND STANDARD ERRORS FOR DAILY GAIN (KILOGRAS/DAY) Tie Actual Adjusted Period Period Period Period Period Period Period Test respectively. The size of these percent relative gains suggests that straightbred steers were apparently receiving less ilk preweaning and did adjust and start on feed sooner at weaning. Reciprocal Crosses. Reciprocal cross (A x S vs S x A) contrasts were evaluated for both actual and adjusted period and test daily gains (table 5). None of the contrasts were significant, indicating no differential aternal influence on postweaning daily gain. Siilar results were observed by Lasley et al. (1973) with both full-fed and deferred-fed straightbred and crossbred Angus, Hereford and Charolais steers. LITERATURE CITED Chapan, H. D., T.. Clyburn and W. C. ccorick Grading and two-and three-breed rotational crossing as systes for production of slaughter steers. J. Ani. Sci. 32:1062. Cundiff, L. V Experiental results on crossbreeding cattle for beef production. J. Ani. Sci. 30:694. Drewry, K. J., S. P. Becker, T. G. artin and L. Nelson Crossing Angus and ilking Shorthorn cattle: Calf perforance to weaning. J. Ani. Sci. 46:83. Gregory, K. E., L. A. Swiger, R.. Koch, L. J. Sup- tion, J. E. Ingalls, W. W. Rowden and J. A. Rothlisberger. 1966a. Heterosis effect on growth rate of beef heifers. J. Anita. Sci. 25:290. Gregory, K. A., L. A. Swiger, L. J. Suption, R.. Koch, J. E. Ingalls, W. W. Rowden and J. A. Rothlisberger. 1966b. Heterosis effects on growth rate and feed efficiency of beef steers. J. Anita. Sci. 25:299. Harvey, W. R Least-squares analysis of data with unequal subclass nubers. USDA, ARS Jain, J. P., J. F. Lasley, B. Sibbit, L. Langford, J. E. Cofort, A. J. Dyer, G. F. Krause and H. B. Hedrick Growth traits of reciprocally crossed Angus, Hereford and Charolais heifers. J. Ani. Sci. 32:399. Kincaid, C Breed crosses with beef cattle in the South. Coop. Series Bull. 81, Texas Agr. Exp. Sta. Klosteran, E. W., V. R. Cahill and C. F. Parker A coparison of Hereford and Charolais breeds and their crosses under two systes of anageent. Ohio Agr. Res. and Dev. Center Res. Bull Lasley, J. F., B. Sibbit, L. Langford, J. E. Cofort, A. J. Dyer, G. F. Krause and H. B. Hedrick Growth traits in straightbred and reciprocally crossed Angus, Hereford and Charolais steers. J. Anita. Sci. 36:1044. Long, C. R. and K. E. Gregory Heterosis and anageent effects in postweaning growth of Angus, Hereford and reciprocal cross cattle. J. Ani. Sci. 41 : artin, T. G., T. W. Perry, W.. Beeson and. T. ohler High-urea suppleents and preweaning creep feed as factors affecting postweaning perforance of bulls. J. Ani. Sci. 44:739. Pahnish, O. F., B. W. Knapp, J. J. Urick, J. S. Brinks and F. S. Willson Results fro crossing beef X beef and beef dairy breeds: Postweaning perforance of heifers. J. Ani. Sci. 33:736. Sith, G.., D. B. Laster, L. V. Cundiff and K. E. Gregory Characterization of biological types of cattle. I1. Postweaning growth and feed efficiency of steers. J. Ani. Sci. 43:37. Vogt, D. W., J. A. Gaines, R. C. Carter, W. H. cclure and C.. Kincaid Heterosis fro crosses aong British breeds of beef cattle: Postweaning perforance to slaughter. J. Ani. Sci. 26:443. Warwick, E. J Crossbreeding and linecrossing beef cattle experiental results. World Review of Anial Production. Vol. IV No :37.