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BUL810 Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and Charolais Cattle 1 F.M. Peacock, M. Koger, E.M. Hodges, J.R. Crockett, and A.C. Warnick2 1. This document is BUL810, one of a series of the Animal Science Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date December 1979. Reviewed June 2003. Visit the EDIS Web Site at http://edis.ifas.ufl.edu. 2. F.M. Peacock, Professor, Department of Animal Husbandry, Agricultural Research Center, Ona; M. Koger, Professor of Animal Genetics, Department of Animal Science; E.M. Hodges, Professor, Department of Agronomy, Agricultural Research Center, Ona; J.R. Crockett, Associate Professor, Department of Animal Genetics, Agricultural Research and Education Center, Belle Glade; and A.C. Warnick, Professor of Animal Physiology, Department of Animal Science, Gainesville. Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, 32611. The Institute of Food and Agricultural Sciences (IFAS) is an Equal Employment Opportunity Affirmative Action Employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service / Institute of Food and Agricultural Sciences / University of Florida / Larry R. Arrington, Interim Dean Crossbreeding of beef cattle has been widely used to achieve improvements in beef production. The appropriate choice of breeds in crossbreeding depends upon the additive genetic merit of the breeds involved and heterosis resulting from the crossing of these breeds. Information on average breed effects and heterosis levels in various crosses thus are important to commercial producers. This paper presents data on results from straight breeding and reciprocal crossbreeding of cattle of the Brahman, Charolais, and Angus breeds. These breeds were selected for the study because of their distinctive characteristics and availability for commercial production in Florida and the southeastern United States. The Charolais breed is noted for muscling and size; the Brahman for adaptability to the subtropical environment and combining ability with other breeds; the Angus for generally good fertility and carcass quality. These breeds represent three divergent breed types of importance in the United States. The Charolais represents the large European beef breeds, the Brahman represents Bos indicus cattle and the Angus represents cattle of British origin. The data presented include those for reproductive performance, weaning traits of calves, and annual production per cow. MATERIALS AND METHODS The research was conducted at the University of Florida Agricultural Research Center, Ona, Florida, from 1963 to 1974. The center is located 27 0 25' north latitude, 81 0 55' west longitude on low-fertility sandy soil. Average annual rainfall is 54 inches with 75% of the precipitation occurring between May and October. The climate is semi-tropical with temperate intrusions during the winter. These intrusions are characterized by repeated frost periods with temperatures of 28 0 to 34 0 F with lower temperatures occurring at less frequent intervals. The herds were maintained on improved grass pastures composed predominately of Pangola digitgrass ( Digitaria decumbens ), moderately fertilized. The cattle were supplemented with 5 pounds of either molasses or citrus pulp-cottonseed meal (4:1 ratio) per head per day for approximately 90 days during late winter and early spring.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 2 The design used to produce straightbred and firstcross (F1) progeny is shown in Table 1 Sires of each breed were exposed each year to cows of each of the three breeds, in a balanced design. A total of 27 sires were used in the project, nine for each of the three breeds. Sires were selected subjectively to be representative of their breed. Females were selected in a similar manner. Cows were culled from the herd annually for unsoundness or reproductive failure; herd replacements averaged 19.6% per year. The mating season was restricted to 90 days beginning in early March. Male calves were castrated shortly after birth. Calves were weaned all at one time at an average age of 222 days. DATA ANALYSES The criteria for evaluating reproductive performance were pregnancy rate, calf survival rate, and weaning rate. Pregnancy rate was expressed as the percentage of cows exposed to bulls which were diagnosed pregnant by palpation in late August. Survival rate was expressed as the percentage of preanant cows which weaned calves. Weaning rate was computed as the product of pregnancy and survival rates. Individual calf records were maintained for date of birth, survival, sex, age at weaning, weaning weight, estimated 205-day weight, and condition score. Condition scores of 6, 7, and 8 were used to designate low, medium, and high standard calves; 9 to 11, good calves; and 12 to 14, choice calves. Average production per cow was computed as the product of weaning weight x weaning rate. Statistical analyses were performed by usual least squares procedures as described by Harvey (2). The analyses shown in Table 2 and Table 3 appeared to be the most appropriate for this study. The objective was to obtain unbiased estimates of breed-of-sire x breed-of-dam subclass means. Year and age of dam (3 years, 4 years, and mature) effects were included in the analyses for statistical precision. Significant levels between means were determined by the standard t test (Peacock et al., 5; Peacock et al., 6). EXPERIMENTAL RESULTS The analyses of variance for reproduction and production traits are shown in Table 2 and Table 3 respectively. The means for reproduction traits are presented in Table 4 and those for production traits in Table 5 Observed heterosis levels (percent advantage of crossbreds over the average of parental breeds) are presented in Tables 4 and 5. Breed of sire, breed of dam, and breed of sire x breed of dam interaction were the items of primary interest in this study. REPRODUCTION Pregnancy Rate The least squares mean for pregnancy rate was 78.6%. Breed of sire had significant effects (P < 0.05) on pregnancy rate, being lowest for Angus sires (74.4%), intermediate for Charolais sires (79.1%) and highest for Brahman sires (82.3%). Peacock et al. (7), at the same location, reported a pregnancy rate of 76% for Brahman bulls vs. 72% for Shorthorn bulls (P < 0.05). Similar results were reported by Turner et al. (11) with cows mated to Brahman bulls having the highest pregnancy rate and those mated to Angus bulls the lowest. However, data reported by Crockett et al.(1) from the Everglades area of south Florida showed that Angus and Hereford bulls had higher calf crops than Brahman bulls. Differences in pregnancy rate were not significantly influenced by breed of dam (Table 2). These results did not agree with those of Crockett et al. (1), who reported birth rate for Angus cows to be 88.7% as compared with 73.7% for Brahman cows. Research in Louisiana (Turner, et al., 11), however, agreed with results from the present study, showing Brahman cows to have a higher calving percentage (78.0%) than Angus (71.3%) or Hereford (72.8%) cows. Research by Peacock et al. (7) on straightbreeding and reciprocal crossing of the Brahman and Shorthorn cattle also showed a higher average pregnancy rate for the Brahman cows, 71% vs 64% for Shorthorns. In the present study, pregnancy rates for cows mated to produce crossbred calves (77.1%) were slightly lower (P < 0.10) than those for cows mated to produce straightbred calves (81.5%).
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 3 Calf Survival Calf survival is an important factor affecting net reproductive efficiency. Survival rate was influenced significantly by breed of dam, but not by breed of sire ( Table 2 ). The average survival rate for all calves was 94.3% (Table 4 ). This value was lower than that of 96.0% reported by Peacock et al. (7), but higher than the 92.0% observed by Turner et al. (11) or the 88.5% reported by Crockett et al. (1) Survival rates were 88.7%, 97.2%, and 96.9% (P < 0.01), respectively, for calves from Angus, Brahman, and Charolais dams (Table 4). There were no significant breed of sire x breed of dam interactions. Mean survival rates were 87.0%, 86.5%, and 92.6%, respectively, for Brahman x Angus, Charolais x Angus, and Angus x Angus calves. Average survival rates for all straightbred and F1 calves were 94.3% and 94.2%, respectively. Turner et al. (11) reported survival rates of 80.5% for Brahman x Angus and 92.6% for Angus calves, which were similar to the results obtained during this study. Sagebiel et al. (10) reported significantly higher dystocia scores for Angus cows than for Hereford and Charolais cows. Pahnish et al. (4) reported no heterosis for birthweights of F1 Angus x Charolais calves, while reciprocal F1 Charolais x Angus calves showed heterosis levels of 4.6% and 5.1%, respectively, for males and females. Weaning Rate Weaning rate was computed as the product of calving and survival rates. Breed of sire effects were nonsignificant. Breed of dam effects were significant, and there was a highly significant breed of sire x breed of dam interaction ( Table 2 ). The overall least squares mean for weaning rate was 74.1%. Comparative rates by breed of dam were 69.8%, 76.5%, and 75.9%, respectively, for Angus, Brahman and Charolais cows (Table 4 ). The average values for reciprocal combinations were 70.0% for Angus-Brahman, 67.7% for Charolais-Angus and 80.2% for Charolais-Brahman. Weaning rates were 76.9% for straightbred calves and 72.7% for F1 calves. The breed of sire x breed of dam interaction is of special interest, since the merit of crossbreeding is determined by the additive genetic merit of each breed plus that achieved through interaction effects. The Charolais x Angus cross resulted in the lowest weaning rate (63.8%) while the Charolais x Brahman cross was highest (82.2%). The differences were due mainly to the relatively low survival rate for Charolais x Angus calves (86.5%) and high survival rate (99.6%) for Charolais x Brahman crosses. The advantages for crossmated groups over the mean of the straightbred groups are presented in Table 4. Considering the three characteristics measured as calf traits, heterosis was negative for all breed combinations and traits except survival and weaning rate for Brahman-Charolais crosses. WEANING TRAITS Age of Calf at Weaning When mating occurs in a restricted season and all calves are weaned at one time, age of calf at weaning becomes an important production trait influencing the weight of calf at weaning. Consequently, age at weaning was analyzed as a production trait in this study. The overall least squares mean for age at weaning was 222.4 days. A number of responses may influence this trait, including length of gestation, interval from parturition to first estrus, aggressiveness and mating ability of bulls, and fertility of both males and females once coupling is achieved. Significant (P < 0.01) differences in weaning age occurred for breed of sire and breed of dam, with no significant breed of sire x breed of dam interaction (Table 3). Age at weaning for straightbred matings was 211.4, 224.5, and 235.3 days, respectively, for Brahman, Charolais, and Angus breeds. Breed of sire and breed of dam effects, respectively, pooled over all groups, were 214.8 and 217.9 days from Brahman, 227.3 and 219.6 for Charolais, and 225.1 and 229.6 for Angus breeds. Age at weaning for crossbred calves was intermediate between weaning ages of parent breeds with no indication of heterosis for this trait.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 4 Positive effects on age at weaning by both Angus sires and Angus dams suggest that length of gestation was an important factor in breed effects in this project. This indication is supported by the report of Sagebiel et al. (9), showing a shorter gestation period for the Angus than for the Charolais (279 vs 285 days), and a report by Plasse et al. (8) showing gestation length (291 days) in the Brahman breed to be considerably longer than those reported for the British breeds. Condition Score This trait is of interest because it is known to be influenced by important factors, including breed characteristics, general well-being of the calf, and maternal ability of the dam. Up to the point of optimum degree of fatness there is a positive relationship between condition score and market value. The mean condition score was 9.6, slightly less than average good in terms of federal grade. Scores were influenced significantly (P < 0.01) by year, sex of calf and age of dam ( Table 3 ). The condition scores for straightbred calves were 8.9 for Brahman and 9.4 for Angus and Charolais (P < 0.05). Mean scores of breed of dam varied only from 9.6 to 9.7 ( Table 5) Mean scores by breed of sire were 9.4, 9.6, and 9.9, respectively for the Brahman, Charolais and Angus breeds (P < 0.01). These differences are in agreement with the general evaluation of these breeds with respect to the ratio of fat to lean. Heterosis levels for each of the breed combinations were highly significant amounting to 9.8%, 5.5%, and 5.3%, respectively, for the reciprocal Angus-Brahman, Charolais-Brahman, and Angus-Charolais crosses. These results are in agreement with other reports generally showing high levels of heterosis in Brahman-British breed crosses (Koger et al., 3). Calf Weight The effects of the different variables on weaning weight and estimated 205-day weight were almost identical. The results from weaning weight only, therefore, will be discussed. All variables included in the model had highly significant effects on calf weights (Table 3). The weaning weights of the straightbred groups were 390, 398, and 519 pounds, respectively, for the Angus, Brahman, and Charolais calves (Table 5). Weights of the crossbred groups varied from 506 pounds for C x B to 437 pounds for B x A calves. The average weight for all crossbreds exceeded that for the straightbreds by 30 pounds, or 6.9%. Heterosis levels were a highly significant 12% for A-B and 7% for C-B but a nonsignificant 2% for A-C crosses. These results indicate high levels of heterosis among crosses of the British and Brahman breeds but only low levels from crossing the Angus and Charolais breeds. ANNUAL PRODUCTION PER COW This trait is a measure of total production performance and is highly correlated with total economy of beef cattle production. It is a composite trait including genetic components for cow fertility, growth potential of the calf, calf survival, and maternal ability of the cow. Each of these components is in turn influenced by additive breed and heterosis effects. The mean annual production per cow was 338 pounds of calf at weaning ( Table 5 ). Of the nine breed-of-sire x breed-of-dam subclasses, the straightbred Angus group was the lowest with 286 pounds. This value was associated with the lowest weaning weight and the lowest weaning rate. The largest annual production of 416 pounds was from Brahman cows mated to Charolais bulls. This production level resulted from the highest weaning rate of 82% combined with the second highest weaning weight of 506 pounds. These values emphasize the impact of weaning rate on annual production rate. Annual production by sire breeds pooled over all breeds of dams was 311, 335, and 367 pounds respectively for Angus, Brahman, and Charolais sires. Comparable values by breed of dam were 297, 344, and 373 pounds. These production levels parallel breed size, as might be anticipated.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 5 Heterosis levels for annual production were -9%, 3%, and 10%, respectively, for Angus-Charolais, Angus-Brahman, and Brahman-Charolais crosses. The low value for Angus-Charolais crosses was associated with genetic size and growth potential of the Angus breed and a high death loss among progeny of Charolais bulls mated to Angus cows. These results emphasize the need for compatibility in size of sires with that of dams to which they are mated, if high death losses in calves are to be avoided. The heterosis level of 3% for reciprocal Brahman-Angus crosses resulted from a high level of beterosis for growth (12%) combined with a negative beterosis (-8.4%) for weaning rate, once again emphasizing the overriding importance of weaning rate in total performance. DISCUSSION It should be noted that this report presents the results from the first phase of a crossbreeding project designed to evaluate the Angus, Brahman, and Charolais breeds as straightbreds and crossbreds. The crossbred heifers evaluated during the first phase of the project reported here will be carried forward into the second phase of the project, where they will be evaluated as crossbred dams. The most important results from the first phase of the project were the following. (1) Hybrid vigor levels vary widely with breed combinations, as demonstrated by a heterosis level of 12% for weaning weight in Brahman-Angus crosses but only 2% in Angus-Charolais crosses. (2) Incompatibility in characteristics such as size of fetus and size of cow can lead to disasterous results in unwise breed combinations, as was demonstrated by mating Charolais bulls to Angus cows in this trial. When the advantages for breed-cross matings over straightbred matings were calculated for the three reproductive traits, seven of nine of these differences were negative ( Table 4 ). These breed combinations might be used successfully, however, where crossbred rather than straightbred cows are used as dams. This point will be elucidated during the second phase of the project, to be reported at a later date. SUMMARY Straightbred and reciprocal firstcross progeny of the Angus, Brahman, and Charolais breeds were produced by mating sires and females of the three breeds in all possible combinations in a balanced design. A total of nine sires of each breed were used over a period of 11 years. The data from 1092 matings, resulting in 863 pregnancies, and 817 complete weaning records were analyzed. Mean pregnancy rates were 81.5% for straightbred matings and 77.1% for crossmatings (P < 0.10). The effects of crossmating were negative for all breed combinations but not significantly so for the numbers involved. Pregnancy rates by breed of sire were 82.3%, 79.1%, and 74.4%, respectively, for Brahman, Charolais, and Angus sires. Pregnancy rates by breed of dam were almost identical. Calf survival was significantly influenced by breed of dam (P < 0.01). This result is explained on the basis of heavy death loss in calves from Angus cows mated to either Brahman or Charolais bulls (P < 0.01) with heavy death losses apparently explained by difficult birth. Except for Angus cows, weaning rate closely paralleled pregnancy rate. Earliness of calving (determined by age of calf at weaning) was negatively influenced by Brahman sires (P < 0.01) and positively influenced by Angus dams. Heterosis effects for weaning age were negligible. Condition scores of calves were negatively influenced by Brahman sires (P < 0.01) and positively influenced by Charolais dams. Heterosis effects were significantly positive for all breed combinations, being 9.8%, 5.5%, and 5.3%, respectively, for Angus-Brahman, Brahman-Charolais, and Angus-Charolais crosses. Weaning weights were 492, 438, and 437 pounds, respectively, for C, A, and B sires (P < 0.01) and 491, 450, and 426 pounds for C, B, and A dams (P < 0.01). Heterosis levels were 12%, 7%, and 2%, respectively, for A-B, B-C, and A-C crosses. Annual production per cow was strongly influenced by calf survival, resulting in low production rates for Angus cows mated to either Charolais or Brahman bulls.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 6 LITERATURE CITED 1. Crockett, J.R., R.W. Kidder, M. Koger, and D.W. Beardsley. 1973. Beef production in a crisscross breeding system involving the Angus, Brahman, and Hereford. Fla. Agr. Exp. Sta. Tech. Bull. 759. 2. Harvey, W.R. 1975. Least-squares analyses of data with unequal subclass numbers. A.R.S. H-4 USDA. 3. Koger, M., F.M. Peacock, and J.R. Crockett. 1975. Heterosis effects on weaning performance of Brahman-Shorthorn calves. J. Anim. Sci. 40:826. 4. Pahnish, O. F., J. S. Brinks, J. J. Wick., B. W. Knapp, and T. M. Riley. 1969. Results from crossing beef x beef and beef x dairy breeds: calf performance to weaning. J. Anim. Sci. 28:291. 5. Peacock, F. M., J. R. Crockett, and A. C. Warnick. 1977. Reproductive performance and crossbreeding Angus, Brahman and Charolais cattle. J. Anim. Sci. 44:729. 6. Peacock, F. M., M. Koger, and E. M. Hodges. 1978. Weaning traits of Angus, Brahman, Charolais and F1 crosses of these breeds. J. Anim. Sci. 47:366. 7. Peacock, F. M., M. Koger, W. G. Kirk, E. M. Hodges, and A. C. Warnick. 1971. Reproduction in Brahman, Shorthorn and crossbred cows on different pasture programs. J. Anim. Sci. 33:458. 8. Plasse, D., A. C. Warnick, R. E. Deese, and M. Koger. 1968. Reproduction behavior of Bos indicus females in subtropical environment II. Gestation length in Brahman cattle. J. Anim. Sci. 27:101. 9. Sagebiel, J. A., G. F. Krause, Bob Sibbit, L. Langford, A. J. Dyer, and John F. Lasley. 1973. Effect of heterosis and maternal influence on gestation length and birth weight in reciprocal crosses among Angus, Charolais and Hereford cattle. J. Anim. Sci. 37:1273. 10. Sagebiel, J. A., G. F. Krause, B. Sibbit, L. Langford, J. E. Comfort, A. J. Dyer, and J. F. Lasley. 1969. Dystocia in reciprocally crossed Angus, Hereford and Charolais cattle. J. Anim. Sci. 29:245. 11. Turner, J. E., B. R. Farthing, and G. L. Robertson. 1968. Heterosis in reproductive performance of beef cows. J. Anim. Sci. 27:336.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 7 Table 1. Table 1. Number of matings by breed of sire and breed of dam. Breed of sire Breed of dam Angus Brahman Charolais Total Angus 126 107 112 345 Brahman 118 128 121 367 Charolais 128 116 136 380 Total 372 351 369 1092 Table 2. Table 2. Mean squares from variance analyses of reproductive traits. Source Degrees of freedom Pregnancy rate Survival rate Weaning rateh Year 10 .9327** .0446 --Age of dam 2 .7868** .2408** --Breed of sire (S) 2 .5632* .0352 32.68 Breed of dam (D) 2 .0019 .6345** 60.82* S x D 4 .3039 .0780 56.09** Within a .1480 .0485 16.06 df in error (1071) (842) (793) aShown in parentheses under errorbProximate analysis of mating group means (pregnancy rate x survival rate). *P<0.05 **P<0.01
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 8 Table 3. Table 3. Mean squares from variance analyses of weaning traits. Source IF Age atweaning Condition Weaningweight 205-dayweight Annualprod/cow a Year 10 9277** 9.7** 236** 401** --Sex 1 1345 38.4** 1447** 1583** --Age of dam 2 6609** 10.7** 876** 290** --Breed of sire 2 11742** 16.0** 2593** 1369** 534 Breed of dam 2 9988** 0.4 2877** 3501** 931* S x D 4 595 17.7** 698** 691** 250 Within 795 861 1.4 44 21 289.5 aFrom a proximate analysis of mating group subclass means (weaning rate x weaning weight).*P<0.05 **P<0.01
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 9 Table 4. Table 4. Least squares means for reproductive traits by mating groups. Group or effecta Number of matings Pregnancy rate Calf survival Weaning rateb Mu 1092 78.6% 94.3% 74.1% 1. A x A 126 79.2 92.6 73.3 2. B x B 128 84.3 94.3 79.5 3. C x C 136 81.1 96.1 77.9 4. A x B 118 69.6 97.6 67.9 5. B x A 107 83.0 87.0 72.2 6. A x C 128 74.4 96.2 71.6 7. C x A 112 73.7 86.5 63.8 8. B x C 116 79.5 98.5 78.3 9. C x B 121 82.5 99.6 82.2 Angus sires 372 74.4 95.5 70.9 Brahman sires 351 82.3 93.3 76.7 Charolais sires 369 79.1 94.1 74.6 Angus dams 345 78.6 88.7 69.8 Brahman dams 367 78.8 97.2 76.5 Charolais dams 380 78.3 96.9 75.9 Purebreds 390 81.5 94.3 76.9 Crossbreds 702 77.1 94.2 72.7 Advantage for crossmating Ho(AB)c, 1/2(4 5-1-2) -5.5 -1.2 -6.4 Ho(AC),1/2(6 7-1-3) -6.1 -3.0 -7.9 Ho(BC), l/2(8 9-2-3) -1.7 3.8 1.6
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 10 Table 4. Advantage as percent of purebred average Ho(AB) -6.7 -1.3 -8.4 Ho(AC) -7.6 -3.2 -10.4 Ho(BC) -2.1 4.0 2.0 aBreed designation: A, B, and C indicate Angus, Brahman, and Charolais, respectively. Breed of sire shown first for mating groups.bWeaning rate x weaning weight. cBreed combinations enclosed in parentheses include reciprocal matings combined.
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 11 Table 5. Table 5. Least squares mating group means, and calf heterosis for weaning traits. Matingagroup Number ofObservations Age atweaning Condition Weaning weight 205-dayweight Production/Cowb days score lbs lbs lbs Mu 817 222.4 9.6 456 428 338 1. A x A 94 235.3 9.4 390 351 286 2. B x B 103 211.4 8.9 398 392 317 3. C x C 107 224.5 9.4 519 482 404 4. A x B 80 219.5 10.2 447 423 303 5. B x A 75 219.1 9.8 437 417 316 6. A x C 94 220.3 10.0 477 451 342 7. C x A 72 234.5 9.7 450 405 287 8. B xC 93 213.8 9.5 477 462 373 9. C x B 99 222.9 9.7 506 472 416 Angus sires 268 225.1 9.9 438 408 311 Brahman sires 282 214.8 9.4 437 424 335
Beef Production from Straightbreds and Reciprocal Crosses of Angus, Brahman, and.... 12 Table 5. Charolais sires 294 227.3 9.6 492 453 367 Angus dams 241 229.6 9.6 426 391 297 Brahman dams 282 217.9 9.6 450 429 344 Charolais dams 294 219.6 9.7 491 465 373 Purebreds 304 223.7 9.2 436 408 336 Crossbreds 513 221.7 9.8 466 438 340 Heterosis in units of measurement Ho(AB)C 1/2(4 5-1-2) -4.0 0.9 48 48 9 Ho(AC) 1/2(6 7-1-3) -2.5 0.5 9 11 -30 Ho(BC) 1/2(8 9-2-3) 0.4 0.5 33 30 35 Heterosis as percent of purebred average Ho(AB) -1.8 9.8 12 13 3 Ho(AC) -1.1 5.3 2 3 -9 Ho(BC) 0.2 5.5 7 7 10 aBreed designation: A, B, and C indicate Angus, Brahman, and Charolais, respectively. Breed of sire shown first for mating groups.bWeaning rate x weaning weight. cBreed combinations enclosed in parentheses include reciprocal matings combined.