BREED MEANS FOR AVERAGE DAILY GAIN, FEED CONVERSION AND INTAKE OF BEEF BULLS DURING POSTWEANING FEEDLOT PERFORMANCE TESTS112

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1 BREED MEANS FOR AVERAGE DAILY GAIN, FEED CONVERSION AND INTAKE OF BEEF BULLS DURING POSTWEANING 112 J. J. Chewning, A. H. Brown, Jr., Z. B. Johnson and C. J. Brown University of Arkansas, Fayetteville ABSTRACT Comparisons of ADG, feeagain, daily feed intake and daily feed intake as percentage of body weight may be important to beef cattle producers and researchers in breed selection and computer modeling. Data evaluated were postweaning feedlot performance test records collected from 167 to 186 of,661 individually fed bulls. Bulls originated from University of Arkansas purebred herds, Fayetteville, and the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope and Monticello. Data were analyzed separately for years 167 to 176 (Pl) (n = 1,65) and 177 to 186 (P2) (n = 2,007). Breeds in P1 were (HH), (AN), (CH), (HP) and (SG). Breeds in P2 were HH, AN, CH, HP, SG, Simmental (SM), Maine- Anjou (MA), Brangus (BN) and Beefmaster (BM). The model fitted included initial age, breed and test number (au P <.01 except for initial age on ADG in Pl). Test number included variation of year, location and season. Breed rankings from highest to lowest for ADG in P1 were CH, SG, HH, HP and AN and in P2 were MA, CH, SM, AN, HP, SG, HH, BN and BM. Breed rankings from highest to lowest for feed/gain in P1 were AN, SG, CH, HP and HH and in P2 were BM, BN, AN, SG, HI, SM, HH. MA and CH. Breeds highest to lowest for daily feed intake (as-fed basis) in P1 were CH, SG, AN, Hp and HH and in P2 were SM. MA, CH, AN, BN, HP, SG, HH and BM. Breeds highest to lowest for daily feed intake as a percentage of body weight in P1 were AN, HH, HP, SG and CH and in P2 were AN, HP, HH, MA, BN, SM, CH, BM and SG. These results suggest that differences exist between breeds for A X, feeagain, daily feed intake on both an absolute and a percentage of body weight basis. (Key Words: Beef Cattle, Bulls, Breeds, Feed Intake, Feed Conversion.) J. him. Sci :150@-150 Introduction To remain profitable, commercial cattle producers must balance production costs against revenues generated within a system subject to large economic changes. Breed selection can influence costs per unit of animal produced and value per unit when sold. Comparison of beef breeds for performance traits can improve a producer s ability to make *Published with approval of the Director of the Univ. of Arkansas Agric. Exp. Sta. A publication of Southern Region Development Committee SRDC bept. of him. and Poult. Sci. Received June 1,18. Accepted October, 18. economically sound decisions. In addition, with the increasing role of computer simulation in production decisions, accurate information about the performance of different breeds is crucial for accurate modeling. Due to the paucity of data on feed intake of beef bulls, the objectives of this study were to make breed comparisons of ADG, feed conversion (feed/ gain) (FCONV), daily feed intake (FI) and feed intake as a percentage of body weight (FIP) during postweaning feedlot bull performance tests. Materials and Methods Data used in breed comparisons for ADG, FCONV, Fl and FIP were postweaning feedlot performance test records collected from 167

2 BREED MEANS FOR PERFORMANCE TRAITS 1501 to 186 of,661 individually fed bulls. Bulls 21-d adjustment period to become accustomed originated from University of Arkansas Agri- to the feeding regimen. Bulls were placed in culture Experiment Station purebred herds in feeding stalls 2 h in the morning and 2 h in the Fayetteville and University of Arkansas Coop afternoon. Individual intake was measured by erative Bull Tests at Fayetteville (one test per weighing feed and orts each day. Shrunk year), Hope (two tests per year) and Mon- weights were taken every d after withholdticello (one test per year). Bulls were evaluated ing feed and water overnight. Mid-weight was in 6 10-d tests. calculated as (initial weight + final weight)/2. Data were analyzed separately for years Feed intake as a percentage of body weight 167 to 176 (Pl) (n = 1,65) and 177 to was calculated as [(total feed consumed)/l0 186 (P2) (n = 2,007) to more accurately d]/mid- weigh t. reflect the breed means during the last 12 yr. At each location each year, the diet was The number of bulls, farms of origin, tests, % cottonseed hulls, % cracked corn, % locations where evaluated and years evaluated crimped oats, 1% cottonseed or soybean by period and breed are given in Table 1. meal, 1% calcium carbonate and 2,200 IU Breeds evaluated in P1 were (HH), vitamin A per kilogram of feed on an air-dry (AN), (CH), basis. As formulated WRC, 1761, the diet (HP) and (SG). Breeds evaluated in P2 were HH, AN, CH, HP, SG, Simmental (SM), Maine-Anjou (MA), Brangus (BN) and Beefmaster (BM). No breed having less than 5 bulls evaluated originating from at least different farms was included. Bulls were required to be between 2 and 00 d of age at delivery. Mean initial ages were 261 d for P1 and P2 with SD of 5 and 2 d, respectively. Upon arrival, bulls were individually identified and sorted by weight into groups of. Groups were assigned randomly to exercise lots; within lots, each bull was assigned randomly an individual feeding stall. Bulls were allowed a contained 1.6 Mcal NE, and. Mcal NE,kg DM and 12% CP. Water and a mineral mixture were provided free choice in exercise lots. Intake is expressed on an air-dry weight basis. Bulls were selected for evaluation according to criteria established by each breeder; therefore, bulls representing each breed were not a random sample. As discussed by Brown et al. (180), this presents the possibility that breed samples may vary because breeders use different criteria in choosing bulls to be evaluated. Choices among bulls made by breeders are by visual appraisal, which is not closely correlated with the traits measured in this study (Brown et al., 180). However, only those breeds with TABLE 1. NUMBER OF BULLS, FARMS OF ORIGIN, TESTS, LOCATIONS AND YEARS BY PERIODa AND BREED EVALUATED FOR AVERAGE DAILY GAIN. FEED CONVERSION, DAILY FEED INTAKE AND DAILY FEED lntake AS A PERCENTAGE OF BODY WEIGHT DURING POSTWEANING Breed Bulls Farms Tests Locations Years Period 1 Charolals Simmental Maine-Anjou Brangus Beefmaster % aperial 1 = 167 to 176; = 177 to

3 ~~ 1502 CHEWNING ET AL. TABLE 2. MEAN SQUARES FOR THE ANALYSIS OF VARIANCE OF AVERAGE DAILY GAIN (ADG), FEED CONVERSION (FCONV), DAILY FEED lntake (Fl) AND FEED INTAKE AS PERCENT BODY WEIGHT (FIP) BY PERIODa OF BULLS IN 10-DAY Am. FCONV, FI, FP. Source df kg/d feedjgain kg/d %id x Period 1 Test ageb ** 15.0** 1.** 17** 15.88**.OW**.0116** Bred 2.6**.8** **.07** Residual p for initial age.oooo Om R-square,016.18,275,61 Initial agec 1.56** 156.5** 57.71**.021** Test.7**.12** 1.6**.0078** Bred ** 1.57** 58.25**.01** Residual ,0005 p for initial age.866,0082,015,0005 R-square.866,55 S62,17 'Period 1 = 167 to 176; = 177 to 186. kean initial age = 268 f 1 d. 'Mean initial age = 268 f 1 d. **P <.01. bulls originating from a minimum of different farms were included. Regardless of the non-random method of selection used in evaluating each breed, bulls evaluated were the population with records available for purchase by commercial producers; therefore, these data should be of interest. TABLE. LEAST S Q U W MEANS FOR AVERAGE DAILY GAIN (AM;) BY PERIOD' AND BREED OF BEEF BULLS DURING 10-DAY POSTWEANING AM;, Breed Wd SE 1.51.Olb Santa Geruudis c 1.1.Old 1.1.Old 1.27.Ole Maine- Anjou I.67.0b 1.66.Olb Simmental 1.6.Olb c.Old Santa Genrudis de 1..oP Brangus 1..02e Beefmaster 1..0' 'Period 1 = 167 IO 176; = 17 to 186. b*c*dgc~fmeans within the same column and period without a common superscript differ (P <,051. Data were analyzed separately for P1 and P2 for ADG, FCONV, Fl and FIP using the GLM option of SAS (186) with the model Yijkl = p + Ti + B E,,kl, where p = mean, Ti = effect o i' the '& 1 test, B, = effect of the jh breed, = partial regression of Y~,H on initial age and Ei.u = residual error. Test was considered a random effect and breed a fixed effect. Test was expected to include the variation of year, location and season. The test x breed interaction was not fitted due to the large number of missing cells caused by all breeds not being represented in each test. In addition, because breeders did not nominate bulls to all test locations, inclusion of this interaction likely would include variation between breeders in addition to breeds. Results and Discussion Test, breed and initial age effects were significant sources of variation (P <.01) for ADG, FCONV, FI and FIP except for the effects of initial age on ADG in P1 (Table 2). The partial regression coefficients for initial age suggest that younger (or lighter) animals had lower FCONV (feeagain) and lower FI than older animals. This is not unexpected because younger animals are expected to have a stronger growth impetus and more efficient feed utilization than older animals. In addition they partition a lower portion of their nutrients

4 BREED MEANS FOR PERFORMANCE TRAITS 150 TABLE. LEAST SQUARES MEANS FOR FEED CONVERSION (FCONV) BY PERIODa AND BREED OF BEEF BULLS DURING 10-DAY POSTWEANING FCONV. Breed feed/gain SE 7.81.ab Santa Geruudis 7.60.w ctlarolais d 7.17.we ' Beefmaster b Brangus 7.8.0b 7.6.0b 7.2.lo& 7..WC Simmental 7..0' 7..ME Maine-Anjou 6.7.lld 6.68.OSd aperiod 1 = 167 to 176; = 177 to 186. b,c*d*%eans in the same column and period without a common superscript differ (P <.05). TABLE 5. LEAST SQUAREs MEANS FOR DAILY m D INTAKE (FI) BY PERIOD' AND BREED OF BEEF BULLS DURING 10-DAY POSTWEANING H, Breed krrld SE.8.08b Saata Gmrudis.58.12b.82.MC..06d.27.06d Simmental Wb Maie- Anjou ' '.5.MC Brangus.27.12d.26.06d Santa Geruudis.26.15d.15.0d Beefmaster.65.17'.Period 1 = 167 to 176; = 177 to 186. b-c*d%eans withii the same column and period without a common superscript differ (P <.05). toward maintenance than older, heavier animals (Brown et al., 188). The other relationships between initial age and ADG and FIP were not consistent across P1 and P2. These differences may be the result of genetic changes over time that could not be measured in this study. bulls had the highest (P c.05) gains (1.51 f.01 kgfd) and AN the lowest (1.27 f.01 kgd) in P1. In P2, MA, CH and SM had the highest (P <.05) ADG (1.67 f.0, 1.66 f.01 and 1.6 f.01 kg/d, respectively) and BM had the lowest (P <.05; Table ). Most other multibreed experiments were not designed to give accurate rankings of population means for individual breeds. However, HH have been reported to gain at a slightly faster rate than AN (Bogart and England, 171; Cundiff et al., 181; Brown et al., 188); however, this may be compensatory due to lower milk production of HH dams. True for P1, this was not true for P2 of this study. Mean ADG was higher in P2 than in P1 for all breeds except SG. This suggests that improvements over years in ADG have been made. These improvements over time in postweaning bull test performance have been discussed previously by Brown (17), Brown et al. (181) and Simpson et al. (186). and HH ranked highest and lowest (P c.05) for FCONV (fedgain) in P1 (Table ). However, HH were not different from HP (P >.05). In, BM and CH ranked highest and lowest for FCONV (P <.05). However, SG, AN and BN were not different from BM nor was CH different from MA (P >.05). These differences may be related in part to differences in maturation rates and(or) body composition as discussed by Fitzhugh and Taylor (171), Smith et al. (176a,b,c), Notter et al. (18) and Brown et al. (188). In Table 5 are least squares means for FI by period and breed. Differences between breeds for FI should represent differences in body size, gut capacity, appetite and rate of feed passage. In P2, three of the five breeds with the lowest FI were Brahman-derived breeds. These results support the conclusion of Rogerson et al. (168) that Zebu steers had lower DM intakes than did grade (Bos taurus). Least squares means for FIP by period and breed are given in Table 6. Reports in the literature are of limited help in explaining these differences in FIP between breeds. The two lowest breeds in FIP for P2 were Brahman-derivative breeds. The confined feeding methods as used in this evaluation may have biased FI by these breeds downward at the start of the test. However, as the test

5 150 CHEWNING ET AL TABLE 6. LEAST SQUARJ MEANS FOR DAILY FEED INTAKE AS A PERCENTAGE OF BODY WEIGHT (FIF') BY PERIOD' AND BREED OF BEEF BULLS DURING 10-DAY POSTWEANING FEEDLOT PERFORMANCE TESTS FIP. Breed %Id SE Smta Genrudis Maine- Anjou Brangus Simmental Beefmaster Olb.0lC.01c.0d.ad.Olb.OlC.MC.0d.Md.01de.me.0f.0f ~ 'Period 1 = 167 to 176; = 177 to 186. b,c*d.esfmeans within the same column and period without a common superscnpt differ (P <.05). progressed, these bulls adjusted to the feeding environment, so differences caused by this interaction between their psyche and the confined feeding method decreased. These differences between the psyches of Bos iaurus and Bos indicur have been discussed previously by Turner (180). However, FIP by BN was not as depressed as by BM and SG. Two other possible considerations are differences in metabolic rate (particularly between Bos tuurus and Bos indicus) and the,,fact that feed intake may be proportional to a function of body weight (e.g., W.75) rather than to weight per se. Further studies are needed to evaluate the causes of these differences in FIP between breeds. lmplicatlons Differences exist between breeds for ADG, FCONV, FI and FIP. These differences can be used by cattle producers to make economically sound decisions about breed selection concerninn the relative mean value of these breeds for certain performance characteristics. These differences may be helpful for improving the accuracy of computer simulations of production systems. Literature Cited Bogart, R. and N. C. England Feed consumption, daily gain and feed required per unit of gain in beef calves. J. Anim. Sci. 2:20. Brown, A. H., 2. B. Johnson and C. 1. Brown Performance trends of bulls evaluated in 16 cooperative tests. J. him. Sci. 5 (Suppl. 1):5 (Absu.). Brown, A. H., Jr., 2. B. Johnson, I. J. Chewning and C. J. Brown Relationships among absolute growth rate, relative growth rate and feed conversion during postweaning feedlot performance tests. J. Anim. Sci. 66:252. Brown. C. J. 17. Trends in performance of bulls in tested beef herds. Ark. Agric: Exp. Sta.. Ark. Farm Res. XxWI. NO.. p. Brown. C. J., 2. Johnson-and H. Brown, 180. Estimates of partial efficiency of young beef bulls. J. Anim. Sci. 51 : 80. Cundiff. L. V., R. M. Koch, K. E. Gregory and G. M. Smith Characterization of biological types of cat- Ue-Cycle 11. IV. Postweaning growth and feed efficiency of steers. J. Anim. Sci. 5:2. Fitzhugh. H. A., Jr. and St. C. S. Taylor Genetic analysis of degree of maturity. J. Anim. Sci. :717. Notter. D. R.. C. L. Fcrrell and R. A. Field. 18. Effects of bred and intake level on growth and feed efficiency in ram lambs. J. Anim. Sci. 58:560. NRC Nutrient Requirements of Beef Cattle (5th Rev. Ed.). National Academy Press. Washington, DC. Rogason, A., H. P. Ledger and G. H. Freeman Food intake and live weight gain comparisons of Bos indicus and Bos UOWUF steers on a high plane of nutrition. Anim. Prod. :7. SAS SAS User's Guide: Statistics SAS Inst., Inc., Cary, NC. Simpson, J. D., A. H. Brown and C. J. Brown Trends of performance in Arkansas cooperative beef-bull performance tests from 1%2 through 182. Growth Smith, G. M., H. A. Fitzhugh. Jr., L. V. Cundiff. T. C. CartWright and K. E. Gregory. 176a. A genetic analysis of maturing patterns in straightbred and crossbred. and Shorthorn cattle. J. Anim. Sci. :8. Smith, G. M.. H. A. Fitzhugh. Jr.. L. V. Cundiff, T. C. Cartwight and K. E. Gregory. 176b. Heterosis for maturing patterns in, and Shorthorn cattle. J. Anim. Sci. :80. Smith. G. M.. D. B. Laster, L. V. Cundiff and K. E. Gregory. 176c. Characterization of biological types of cattle. 11. Postweaning growth and feed efficiency of steers. I. Aaim. Sci. :7. Turner, 1. W Genetic and biolodcal as~ects of Zebu - adaptability. J. Anim. Sci