LIFETIME PRODUCTIVITY OF PUREBRED AND CROSSBRED COWS OF ANGUS AND MILKING SHORTHORN PARENTAGE: WEIGHTS AND SCORES 1'2'3

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1 LIFETIME PRODUCTIVITY OF PUREBRED AND CROSSBRED COWS OF ANGUS AND MILKING SHORTHORN PARENTAGE: WEIGHTS AND SCORES 1'2'3 S. J. Croak-Brossman, T. G. Martin and L. A. Nelson Purdue University, West Lafayette, IN Summary Lifetime productivity of 242 purebred and reciprocal crossbred Angus (A) and Milking Shorthorn (M) cows was studied. Cows were born in the fall during the 5-yr period from 1966 through Data from each parity, one through six, were analyzed separately by the method of least-squares. The basic statistical model included effects of breed of cow and year of cow birth plus the first-order interaction. Calf weight data were adjusted for effects of sex and calf age. Production stage was included for analyses of cow weights and condition scores. Data from parities seven through 13 were combined in one analysis with the effect of parity added to the model. Appropriate contrasts of estimates of breed means provided estimates of additive, heterotic, maternal and grandmaternal effects. Using pooled averages, crossbred cows were 22.5 kg (5.7%, P.01) heavier and.15 condition score units (5.3%, P.01) fatter than purebred cows. Condition scores of AM, MA and AA cows were higher (P.05) than those of MM cows. Calves from crossbred cows averaged 6.1 and 9.8 kg heavier (4.2 and 4.7%, P.01) at 120 and 210 d of age, respectively, than calves from purebred cows. Calves from AM, MA and MM dams were heavier (P.05) than those from AA dams. Calf weight at 210 d of age as a percentage of cow ~Journal Paper No. 9635, Purdue Univ. Agr. Exp. Sta., Dept. of Anita. Sci. : Data derived from the Purdue Univ. contributing project to NC-1 regional project, Improvement of Beef Cattle Through Breeding Methods. athe authors express appreciation to John R. Hodges and personnel at the Feldun-Purdue Agr. Center for management of the cattle and assistance in data collection. Received November 21, Accepted May 23, weight was used as a measure of efficiency of production. The heterosis contrast was 3.6% (P.01), which represented an 8.5% increase of the crossbreds relative to the mean of purebred cows (42.4%). (Key Words: Lifetime Productivity, Angus, Milking Shorthorn, Beef Cows, Heterosis, Maternal Effects.) I ntroduction Dickerson (1969, 1973) and Hill (1971) described theoretical effects of crossbreeding and heterosis on efficiency of breeding systems. Equations for deriving estimates of breed genetic and maternal effects as deviations from the purebred means were presented by Alenda et al. (1980) and Dillard et al. (1980). Crossbred cows have been reported to be more productive than purebred cows (Collins et al., 1972; Cundiff et al., 1974a,b). Dairy x beef females weaned heavier calves than beef x beef females in studies by Rutledge et al. (1971) and Nelson et al. (1982). Spelbring et al. (1977) reported that crossbred cows produced heavier calves than purebred cows over the first three parities. Differences in productivity of mature crossbred and purebred cows have not been well documented (Martin, 1971; Stewart and Martin, 1981). The objective of this study was to estimate the magnitude of genetic effects on calf weights, cow weight, cow condition score and efficiency of production from data on purebred and reciprocal crossbred cows of Angus and Milking Shorthorn parentage. Materials and Methods Purebred and crossbred calves from purebred Angus (A) and Milking Shorthorn (M) cows were produced in Phase I of this experiment (Drewry et al., 1978) over 5 yr (1966 through 1970). All 242 heifers from Phase I (70 AA, JOURNAL OF ANIMAL SCIENCE, Vol. 59, No. 6, 1984

2 1452 CROAK-BROSSMAN ET AL. AM, 58 MA and 51 MM) were utilized in the present study with no selection. Heifers were exposed to Hereford bulls at 16 to 18 mo of age and calved in late winter at 25 to 27 mo of age. The second calf crop was sired by Charolais bulls. Third and fourth calf crops, in 1973 and 1974, were sired by Hereford, Charolais and Red Poll bulls. The third and later calf crops in all other years were sired by Charolais bulls. Each 60-d breeding season began the first week of May, and most calves were born in February and March. Male calves were castrated within 24 h after birth. Calves were neither implanted with a growth stimulant nor creep-fed before weaning. Cows were weighed and assigned condition scores three times each year at approximately 60, 120 and 210 d postpartum. Condition scores ranged from 1 to 5, with 1 = very thin, 3 = average condition and 5 = very fat. Calves were weighed at average ages of 120 and 210 d. All calf weights were adjusted to a Charolais (C) sire basis by a ratio of least-squares means for sire breeds derived from 1973 and 1974 calf data. There was no interaction between breed of sire and breed of dam in the data. Weights at 120 and 210 d of age were adjusted for sex and age of calf. A ratio of adjusted 210-d calf weight to cow weight was calculated as a measure of cow efficiency and was expressed as a percentage. Statistical Analysis. All analyses were accomplished by the method of least-squares for unequal subclass numbers (Harvey, 1976). The basic model included effects of breed of cow and year of cow birth plus the two-way interaction. Production stage (60, 120 or 210 d postpartum) and interaction of production stage with breed were included in the model for analyses of cow weights and condition scores. Parity one, for weight and score data, included the time period from first parturition to weaning of the first calf. Data from parities one through six were analyzed separately. At parity seven, less than 50% of the cows remained in the study, and data from parities 7 through 13 were combined in one analysis, with the effect of parity included in the model. Pooled mean values from the seven analyses were obtained by proportionally weighting each mean relative to the number of observations. Appropriate contrasts of estimates of breed means (Alenda et al., 1980) provided estimates of maternal additive (gm), maternal heterosis (h~j) and grandmaternal~additive (g~') effects on calf weight. The maternal additive effect was partially confounded with A and M individual additive effects (g~) and individual heterosis effects (h6) involving" Charolais-Angus (CA) and Charolais-Milking Shorthorn (CM) breed combinations [~M= g~+ ZAgi+ ta(hc~,. _ him)]. For cow weight and condition score, the same contrasts measured individual additive (g~), individual heterosis (h I) and the total 'of -j maternal additive and grandmaternal additive (TM i) effects. Results and Discussion Breed of cow and year of cow birth influenced variation (P.05) in cow weight, cow condition score and calf weights in all analyses. The interaction between breed of cow and year of cow birth was not significant (P>.10) in any of the anlayses. Cow Traits. Production stage influenced cow weight (P.05) in parities one through four, but not in later parities. In early parities, cow weight increased from 60 to 120 d and from 120 to 210 d calf age. These weight increases indicated growth of the cow. Analyses of bovine growth curves reported by Fitzhugh et al. (1967), Long et al. (1975), Fitzhugh (1976) and Notter et al. (1979) indicated continuous growth to ages of 45 to 60 mo. Cow weight at fifth and later parities fluctuated very little during the calendar year. Stage of production did not influence cow condition score. The breed of cow x stage of production interaction, which would indicate that breeds changed condition or weights differently during lactation, did not influence (P>.10) either cow weights or condition scores. Least-squares means and standard errors are shown in figure 1 for cow weight averaged over the three stages of production. Reciprocal differences may be estimated as twice the total maternal effect shown in table 1. Individual breed additive effects (table 1) affected (P.10) cow weight in all parities except the fifth with AA cows being 15.4 kg heavier than MM cows. Total maternal effects on cow weights were observed (P.10) in all analyses except parity five. In all cases, cows having MM dams were heavier (average 8.2 kg, P.01) than cows from AA dams. Large positive individual heterotic effects (P.01) were observed for cow weights in all parities. Crossbred cows were 22.5 kg heavier (P.01) than purebred cows when averaged over all parities.

3 LIFETIME PRODUCTIVITY OF COWS ~.~ 425 "I" LLI ~ 400 O '5 ku I1: U.I S50 // ~ M. SHORTHORN (M) ~/ ol/2 (AM+MA) STANDARD ERRORS D & Y , ' , I J I I I I I I I I I I Figure 1. Least-squares means and standard errors of average cow body weight for Angus, Milking Shorthorn and crossbred breed groups in parities 1 through 12. Milking Shorthorn parity 10 mean includes parity 11 weights. Angus and crossbred parity 12 means inelude parity 13 weights. Cow condition scores were not influenced by production stage, but Condition tended to decline between 120 and 210 d postpartum, possibly due to the stress of lactation. The means and standard errors for AA, MM and the AM-MA pooled breed groups are shown in figure 2 for each parity. Reciprocal differences were small (average.02 units) and generally not statistically significant. Within breed group, there was little influence of parity on condition score prior to parity nine or age 10 yr. At older ages, cows were significantly thinner. Data for older cows include the terminal parity when many cows became physically impaired and thin. The reason for termination was most often failure to become pregnant. Breed differences followed a consistent pattern in all parities, and average condition scores, over all parities, were 3.12, 2.99, 2.99 and 2.56, respectively, for AA, AM, MA and MM cows. The average AA individual additive effect (table 1) was (P.01), the average heterotic effect was (P.01) and the average maternal effect was Calf Weights. Adjusted least-squares means and standard errors for 120- and 210-d weights, respectively, are shown in figures 3 and 4. Actual weights at the two ages followed the same patterns as the adjusted weights reported here (Croak-Brossman, 1983). Grandmaternal breed additive effects (table 2) on 120- and 210-d calf weights were small (P>.05) in all analyses. The absence of a grandmaternal (reciprocal) effect on calf weights provided the basis for treating the crossbreds as a single group in later analyses. The magnitude and significance of the grandmaternal effects were considerably smaller than those reported by Alenda et al. (1980). Maternal breed additive effects influenced adjusted 120-d calf weight (P.10) in parities three through six. Maternal breed additive effects on adjusted 210-d calf weights were observed (P.10) in all analyses except parities 1 and 7 through 13. These estimates were confounded with individual additive and individual heterosis effects as described earlier. However, the g~ estimates were_ not greatly influenced_ by confounding if h CA = hc~m" The g~ estimates of Drewry et al. (1978) were small (.95 and.50 kg, respectively, for 120- and 210-d weights). The MM dams produced heavier calves than AA dams in all parities, with mean differences of 9.4 kg (P.01) at 120 d and 12.4 kg (P.01) at 210 d of age. Maternal heterosis effects (table 2) were observed (P.05) in all parities for 210-d calf weight and in all parities except 3 and 7 through 13 for 120-d weight. The average advantages of calves from crossbred dams over those from purebred dams were 6.1 (4.2%, P.01) and 9.8 kg (4.7%, P.01), respectively, at 120 and 210 d of age. However, the economic advantage of crossbred cows associated with heavier calf weights was at least partially offset by crossbred cows being 5.7% heavier (figure 1) than purebred cows. These heterosis estimates were lower than those reported by Collins et al. (1972), Cundiff et al. (1974b) and Reynolds et al. (1982). Weights of calves from MM cows were not different (P>.05) from those of crossbred dams. Calves from AM, MA and MM cows were heavier (P.05) at 120 and 210 d of age than calves from AA dams. These results support those of Belcher and Frahm (1979), Knapp et al. (1980), Frahm et al. (1981) and Nelson et al. (1982), in which beef-dairy crossbred cows produced heavier calves than cows having no dairy ancestry. Efficiency of Production. Least-squares means and standard errors for an estimate of

4 1454 CROAK-BROSSMAN ET AL. +~ +l +i +1 +i +1 "{'~ +1 {/},J +J := o o U I" +~ " +~ " +~ " +~ " +; I" +~ I" +~ I" +~ z z 9 +; 9 +; 9 +~ 9 +; 9 +; 9 +~ 9 +; 9 +; o,= {/1 ~u u ~L ze ~J ~J ~ I +' I +~ I +' I -H I I +~ I +' I +' J II Z +l l +1 +l I1~ ~ e~ Z ~l~ ~,d ~ ~, ~.'~ II M [.., =, M

5 LI FETIME PRODUCTIVITY OF COWS ~-~ +1 ~=~ o,4- +i I +i +~ I +i +i I +t +~ +i 0 0 Z t~ +' I +~ I +~ ~ ~ ~ +' I +~ I +~ I "~ I I I!,.0 Z ~ +1 +~ l +t II.ti +~ I +' +~ I +~ +l I +' I +, I +~ 0., r~ I +j I +l +, ~ +1 I +a I +~ I +' I +' I c/) r~ /3 ~,~ ~ ~.,7- o ~ ~ I " ~ I,,.. [/3 t~

6 1456 CROAK-BROSSMAN ET AL ,0 215 E ~ 2.0 O ~ 1.5 Z (Z 1,1 ~> 1.0 C, M SHORTHORN (M) \ o 1/2 (AM+MA) \ STANDARD ERRORS , Z~ D i i i i i i i I i i i i o, I Figure 2. Least-squares means and standard errors of average cow condition score (1 = very thin, 3 = average condition, 5 = very fat) for Angus, Milking Shorthorn and crossbred breed groups in parities 1 through 12. The Milking Shorthorn parity 10 mean includes parity 11 scores. Angus and crossbred parity 12 means include parity 13 scores n'~ C3 o 1/2(AM-MA) ~X 6 % 175 STANDARD ERRORS LL -J [] ll (..) ~ 3.3 A t2.8 12t , A , I I I I I I I ~ I I I I t Figure 4. Least-squares means and standard errors of calf 210-d weight for Angus, Milking Shorthorn and crossbred breeds of dams in parities 1 through 12. The Milking Shorthorn parity 10 mean includes parity 11 weights. Angus and crossbred parity 12 means include parity 13 weights. cow efficiency, calf weight weaned as a percentage of cow weight and including all cows entering the breeding pasture are presented in figure 5. The ratio tends to adjust for feed requirements, which is the largest single cost variable in maintaining a cow herd. This ratio does not adjust for differential lactation requirements of the breed groups r 45 q R /~.~:x... A /Y I"~ / UJ 150 # 140 s v/ / I:/ ~, M, SHORTHORN (M) - ~ o t/2(am.ma, _.~ 13,0,:Z L) STANDARD ERRORS e ~ 2~ :~ ,0 1.8 L O i i i i i ~ i i i i i i Figure 3. Least-squares means and standard errors of calf 120-d weight for Angus, Milking Shorthorn and crossbred breed groups of dams in parities 1 through 12. The Milking Shorthorn parity 10 mean includes parity 11 weights. Angu s and crossbred Parity 12 means include parity 13 weights. t LU L) o' 0 ~ ~! ~ 2" \ ---o ANGUS~A) ~.! i. / \ -. ~ T I : i O R N (M) \,/ \ / STANDARD ERRORS : ,50 5, t , ;~ t t i i i i i i i i i i i I Figure 5. Least-squares means and standard errors of cow efficiency (calf weight as a percentage of cow weight) for Angus, Milking Shorthorn and crossbred breed groups in parities 1 through 12. The Milking Shorthorn parity 10 mean includes parity 11 efficiencies. Angus and crossbred parity 12 means include parity 13 efficiencies.

7 LIFETIME PRODUCTIVITY OF COWS 1457 TABLE 3. ESTIMATES AND STANDARD ERRORS OF INDIVIDUAL ADDITIVE, TOTAL MATERNAL AND INDIVIDUAL HETEROSIS EFFECTS FOR COW EFFICIENCY OF PRODUCTION a, EXPRESSED AS PERCENTAGES Individual Total Individual Parity No. additive b maternal c heterosis d t , Average 1, * aefficiency of production = Adjusted 210-d calf we,ight 100; zero value was entered for 210-d calf weight when no calf was weaned. Cow weight blndividual additive: gi = AA -- MM -- MA + AM I I ;gm = --ga; A and M subscripts = Angus and Milking Shorthorn. 2 CTotal maternal: TM A = MA -- AM ; TM M = _TMA" 2 dlndividual heterosis: hai M - AM + MA - AA -- MM 2 tp.10. *P.05. Breed of cow exerted very small effects (P>.10) on efficiency of production in the various parity analyses. Estimates of individual breed additive effects (table 3) were variable. Straightbred AA cows produced 4.4% more calf weight relative to body weight than MM cows. Total maternal (reciprocal) effects were very small (P>.10) in all analyses. Estimates of individual heterosis effects were generally small but showed that crossbred cows were more efficient than purebred cows in all parities except the fifth. This contrast was largest (P.10) in the first parity. The average contrast of 3.6% represents an 8.5% increase (P.05) in lifetime efficiency of crossbreds relative to the mean of purebred cows (42.4%). The estimate of heterosis for efficiency of production was lower than that reported by Spelbring et al. (1977) for the first three parities. These results indicate that the efficiency advantage of crossbreds over purebreds is slightly greater in early parities than in later parities; however, the advantage persists to older ages. These results support conclusions drawn by Cundiff et al. (1974a), Belcher and Frahm (1979) and Nelson et al. (1982). Cow and calf weights in parities nine and later indicated a general decline as the cows grew older. The general decline in calf weights, cow weights and cow condition scores beyond parity nine was indicative of cow aging. Literature Cited Alenda, R., T. G. Martin, J. F. Lasley and M. R. Ellersieck Estimation of genetic and maternal effects in crossbred cattle of Angus, Charolais and Hereford parentage. I. Birth and

8 145 8 CROAK-BROSSMAN ET AL. weaning weights. J. Anim. Sci. 50:226. Belcher, C. G. and R. R. Frahm Productivity of two-year-old crossbred cows producing threebreed cross calves. J. Anim. Sci. 49:1195. Collins, J. C., T. B. Patterson, W. M. Warren and G. B. Meadows Crossbreeding British beef breeds. Auburn Univ. Agr. Exp. Sta. Bull Croak-Brossman, S. J Lifetime productivity of purebred and crossbred cows of Angus and Milking Shorthorn parentage. Ph.D. Dissertation. Purdue Univ., West Lafayette, IN. Cundiff, L. V., K. E. Gregory and R. M. Koch. 1974a. Effects of heterosis on reproduction in Hereford, Angus and Shorthorn cattle. J. Anita. Sci. 38:711. Cundiff, L. V., K. E. Gregory, F. J. Schwulst and R. M. Koch. 1974b. Effects of heterosis on maternal performance and milk production in Hereford, Angus and Shorthorn cattle. J. Anita. Sci. 38: 728. Dickerson, G. E Experimental approaches in utilizing breed resources. Anita. Breed. Abstr. 37:191. Dickerson, G. E Inbreeding and heterosis in animals. In: Proc. Anim. Breeding and Genet. Syrup. in honor of J. L. Lush. Amer. Soc. Anita. Sci., Amer. Dairy Sci. Assoc. and Poul. Sci. Assoc., Champaign, IL. p 54. Dillard, E. U., O. Rodriguez and O. W. Robison Estimation of additive and nonadditive direct and maternal genetic effects from crossbreeding beef cattle. J. AnL~n. Sci. 50:653. Drewry, K. J., S. P. Becket, T. G. Martin and L. A. Nelson Crossbreeding Angus and Milking Shorthorn cattle: Calf performance to weaning. J. Anim. Sci. 46:83. Fitzhugh, H. A., Jr Analysis of growth curves and strategies for altering their shape. J. Anita. Sci. 42:1036. Fitzhugh, H. A., Jr., T. C. Cartwright and R. S. Temple Genetic and environmental factors affectingweight of beef cows. J. Anita. Sci. 26:991. Frahm, R. R., D. M. Marshall and C. G. Chenette Productivity comparisons among various two breed cross cow groups. Oklahoma Agr. Exp. Sta. Res. Rep. MP-108:30. Harvey, W. R Least-squares analysis of data with unequal subclass numbers. USDA, ARS, H-4. Hill, W. G Theoretical aspects of crossbreeding. Ann. Genet. Sel. Anim. 3:23. Knapp, B. W., O. F. Pahnish, J. J. Urick, J. S. Brinks and G. V. Richardson Preweaning and weaning heterosis for maternal effects of beef X beef and beef X dairy crosses. J. Anita. Sci. 50:800. Long, C. R., T. C. Cartwright and H. A. Fitzhugh Systems analysis of sources of genetic and environmental variation in efficiency of beef production: Cow size and herd management. J. Anita. Sci. 40:409. Martin, T. G Genetic aspects of dairy beef production. J. Anita. Sci. 32:435. Nelson, L. A., G. D. Beavers and T. S. Stewart Beef X beef and dairy beef females mated to Angus and Charolais sires. II. Calf growth, weaning rate and cow productivity. J. Anita. Sci. 54:1150. Notter, D. R., J. O. Sanders, G. E. Dickerson, G. M. Smith and T. C. Cartwright Simulated efficiency of beef production for a cow-calf-feedlot management system. I. Milk production. J. Anita. Sci. 49:70. Reynolds, W. L., T. M. DeRouen and K. L. Koonce Preweaning growth rate and weaning traits of Angus, Zebu and Zebu-cross cattle. J. Anim. Sci. 54:241. Rutledge, J. J., O. W. Robison, W. T. Ahlschwede and J. E. Legates Milk yield and its influence on 205-day weight of beef calves. J. Anim. Sci. 33:563. Spelbring, M. C., T. G. Martin and K. J. Drewry Maternal productivity of crossbred Angus X Milking Shorthorn cows. I. Cow and calf weights and scores. J. Anita. Sci. 45:969. Stewart, T. S. and T. G. Martin Mature weight, maternal performance and their interrelationships in purebred and crossbred cows of Angus and Milking Shorthorn parentage. J. Anim. Sci. 52:51.