Two-, three- and four-breed rotational crossbreeding of beef cattle: reproductive traits

Reproductive data were collected on 4,596 cow exposures in a rotational crossbreeding study that spanned four generations (1970 through 1988). Angus (A), Brahman (B), Charolais (C) and Hereford (H) breeds were included in three two-breed (A-B, C-B and H-B), three three-breed (A-B-C, A-B-H and C-H-B) and one four-breed (A-B-C-H) rotational mating system. Contemporary straightbreds were produced each generation. Reproductive traits of interest were calving rate, calf survival, weaning rate, calf birth date and calving assistance. Overall means and standard errors for calving rate, calf survival, weaning rate, calf birth date and calving assistance were 82.1 +/- .6%, 92.8 +/- .4%, 76.2 +/- .6%, 50.4 +/- .3 d and 4.2 +/- .3%, respectively. Rotational mating systems had similar calving and calf survival rates that were greater (P less than .01) than those of straightbreds. Three- and four-breed rotation systems had similar weaning rates (81.5 +/- 1.1 and 80.8 +/- 2.0%) that were higher than those for two-breed rotations (77.1 +/- 1.2%). Two- and three-breed rotation systems had fewer assisted births (3.5 +/- .6 and 2.2 +/- .6%) than straightbreds (5.5 +/- .6%) and the four-breed rotation (5.4 +/- 1.0%). Three-breed rotation calves were born earlier in the calving season (46.8 +/- .6 d; P less than .05) than straightbred, two-breed or four-breed rotation calves (51.8 +/- .6, 52.1 +/- .6 and 51.1 +/- 1.0 d). Hereford-Brahman two-breed rotation cows had higher (P less than .05) calving and weaning rates than A-B or C-B two-breed rotation cows (87 +/- .4 vs 81.9 +/- 1.9 and 81.5 +/- 1.8%; 81.7 +/- 2.0 vs 76.4 +/- 2.1 and 74.1 +/- 2.0%). All three-breed rotation combinations had similar calving, calf survival and weaning rates, assistance at calving and calf birth dates. Rotational combinations tended to be more superior (P less than .05) to weighted purebred means for calving, calf survival and weaning rates than for calf birth date and calving assistance.     

Life-cycle evaluation of Bos taurus and Bos indicus X Bos taurus breed types in a dry, temperate climate: performance of mature dams

Mature dams representing Hereford, Red Poll, F1 Hereford x Red Poll, F1 Red Poll x Hereford, F1 Angus x Hereford, F1 Angus x Charolais, F1 Brahman x Hereford and F1 Brahman x Angus breed types were evaluated. All cows were bred to Limousin sires to produce two-way or three-way-cross progeny. Mature Brahman x Hereford dams produced a higher (P less than .05) percentage of live calves than Herefords, but dam breed differences in percentage of calves weaned relative to the number of cows exposed for mating were not statistically significant. Progeny of Angus x Charolais and Red Poll dams were outstanding in weaning weight, but Hereford and Brahman-cross calves were below average. Planned comparisons showed that Angus x Charolais calves were heavier (P less than .01) at weaning than Hereford (23.0 +/- 3.8 kg) or Angus x Hereford (9.6 +/- 3.2 kg) progeny. Mature Angus x Hereford mothers weaned heavier calves than did Brahman x Herefords (7.4 +/- 3.2 kg, P less than .05) or Brahman x Angus (10.9 +/- 3.0 kg, P less than .01). Analysis of the Hereford-Red Poll diallel showed evidence of maternal heterosis in calf weaning weight (4.0 +/- 2.6 kg, P less than .05), but there was no difference in the percentage of calves weaned by crossbred vs straightbred dams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Direct and maternal genetic effects on birth and weaning traits in multibreed cattle data and predicted performance of breed crosses

Direct and maternal additive effects and heterosis were estimated using data from straightbred Angus, Brahman, Charolais, Hereford, and four generations of rotational crosses among these breeds. Traits of interest were birth weight, Julian day of birth, average daily gain from birth to weaning, 205-d weight, and weaning weight per cow exposed. Complete data were available on 3,445 calves produced from 4,733 matings. Discrete generations of 4-yr duration were produced from 1970 through 1988. Brahman was included in each rotational crossbreeding system. Genetic effects were estimated by regression. Direct and maternal additive effects of Brahman, Charolais, and Hereford were estimated as deviations from Angus. Direct and maternal heterosis effects were assumed proportional to expected heterozygosity. The Brahman direct additive effect resulted in later-born calves (P < 0.01). Brahman, Charolais, and Hereford direct additive effects increased birth weight, and the Brahman maternal additive effect decreased birth weight compared with Angus (P < 0.05). Charolais direct and maternal additive effects were greater than Angus for average daily gain and 205-d weight (P < 0.01). The Hereford maternal additive effects on average daily gain and 205-d weight were less than those of the other breeds (P < 0.01). Breed combinations including Brahman had greater direct heterosis for birth weight, average daily gain, and 205-d weight than other combinations (P < 0.01). Angus, Charolais, and Hereford direct additive effects on weaning weight per cow exposed were greater than Brahman (P < 0.05). Predicted average daily gain, 205-d weight, and weaning weight per cow exposed were, on average, greater in four-breed rotation systems than in three- and two-breed systems. Among two-breed rotation systems, predicted average daily gain and 205-d weaning weight were greatest for Charolais-Brahman and least for Angus-Hereford. Calves from the Angus-Charolais-Hereford system weighed less at weaning than any other three-breed combination. However, weaning weight per cow exposed from the Angus-Charolais-Hereford system was greatest among three-breed systems. Within three- and four-breed rotation systems, ranges in predicted birth and weaning weights among generations varied by up to 10.0 and 25.2 kg, respectively. The choice of breeds affects performance, and the sequence of their use may affect intergenerational variation in performance.     

Maternal characteristics of young dams representing Bos taurus and Bos indicus x Bos taurus breed types

Reproductive traits and preweaning growth of progeny from young Hereford, Red Poll, Hereford X Red Poll, Red Poll X Hereford, Angus X Hereford, Angus X Charolais, Brahman X Hereford and Brahman X Angus dams were evaluated. First-calf heifers were mated with Red Angus bulls; Santa Gertrudis sires were used for each cow's second and third breeding season. Herefords, Red Polls and Hereford-Red Poll crosses were below average in percentage of calves weaned, whereas Angus-sired and Brahman-sired dams exceeded the overall mean. Angus X Charolais (P less than .10), Brahman X Hereford (P less than .01) and Brahman X Angus (P less than .10) dams weaned a higher percentage of calves than straightbred Herefords. None of these breed types differed from young Angus X Hereford females in reproductive performance. Angus X Charolais calves ranked highest in 180-d calf weight, exceeding progeny from both Hereford (P less than .01) and Angus X Hereford (P less than .10) dams. Brahman X Hereford dams weaned heavier (P less than .05) calves than Herefords, but their progeny did not differ at weaning from those reared by Angus X Herefords. Calves from Brahman X Angus dams weighed 12.7 kg less (P less than .01) than Angus X Hereford progeny. Analysis of the Hereford-Red Poll diallel showed evidence of (P less than .10) maternal heterosis in 180-d calf weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of crossbred cows containing various proportions of Brahman in spring or fall calving systems: III. Productivity as three-, four-, and five-year olds

Productivity of 3-, 4-, and 5-yr-old crossbred cows containing various proportions (0, 1/4, or 1/2) of Brahman breeding out of Angus or Hereford dams was evaluated using 489 spring-calving and 427 fall-calving records collected over a 4-yr period. Cows were bred to Limousin sires for the first 3 yr and to Limousin and Salers sires the 4th yr. Interactions between crossbred cow group and season of calving were not significant. Percentage of cows exposed to breeding that weaned a calf increased (P less than .01) as proportion Brahman breeding increased, was higher (P less than .01) for cows out of Angus dams than for cows out of Hereford dams, and was higher (P less than .01) for spring-calving cows. As the proportion Brahman increased, the percentage requiring assistance at birth decreased, and cows out of Angus dams required less (P less than .05) assistance than those out of Hereford dams. Preweaning ADG, adjusted weaning weight, weaning conformation, weaning condition, and adjusted weaning hip height increased a proportion Brahman breeding increased. Spring-born calves gained .12 kg/d faster (P less than .01) than fall-born calves. However, weight at weaning was similar for the two groups; spring-born calves were weaned at an average age of 205 d, and fall-born calves were weaned at an average age of 240 d. Fall-calving cows were heavier (P less than .05) than spring-calving cows, and 0 and 1/2 Brahman cows were heavier (P less than .01) than 1/4 Brahman cows. These data indicate that Brahman-cross dams can be used to improve reproductive rate and increase preweaning growth rate, and thus weaning weight.(ABSTRACT TRUNCATED AT 250 WORDS)     

Productive longevity of first-cross cows produced in a five-breed diallel: I. Reasons for removal

Data from 498 cows of 15 breed-types produced in a five-breed diallel (reciprocals pooled) including Angus, Brahman, Hereford, Holstein and Jersey were analyzed for differences in productive longevity, mean life span and reasons for removal from the herd over approximately 14 yr. The only culling related to production was of cows that did not give birth to at least one live calf every 24 mo. Otherwise, cows were only removed when they appeared to be incapable of weaning another live calf. The average age at removal, estimated from linear regression, was 3,470 d, with values ranging from 2,174 d (Jersey) to 4,087 d (Angus-Brahman). Longevity of crossbred cows was greater than that of purebred cows (P less than .001). Purebred cows usually had higher initial rates of removal than crossbred cows. Estimates of mean longevity from the nonlinear regression resembled the results of the linear regression analysis; mean life spans ranged from 6.2 yr (Jersey) to 14.6 yr (Angus-Brahman). The major reason for removal of Brahman and Brahman-cross cows was for reproductive reasons. Angus and Angus-cross cows were culled more frequently for structural unsoundness; Hereford cows had a higher incidence of cancer eye, calving difficulty and mammary problems; cows with 100% dairy breeding had exceptionally high susceptibility to diseases and mineral imbalance.     

Evaluation of crossbred Brahman and continental European beef cattle in a subtropical environment for birth and weaning traits

A total of 528 birth and 475 weaning records collected over a 3-yr period were analyzed to evaluate the productivity of several beef cattle breed crosses. The calves were produced by artificial insemination using 17 Brahman, 15 Chianina, 15 Maine Anjou and 16 Simmental sires bred to Angus and Hereford dams varying in age from 3 to 11 yr. Breed-of-sire effects were important (P less than .05 to P less than .001) for gestation length, birth weight, conformation score and condition score, but were not observed for birth weight adjusted for gestation length, percentage calving assistance, survival rate or weaning weight. Brahman crosses had the longest gestation lengths, being 4.7 d longer than Simmental crosses, which were the shortest in length. Chianina crosses were the heaviest at birth and experienced the most calving difficulty. Simmental crosses had the highest survival rate. Although breed-of-sire differences were observed in conformation score, the difference was less than one-third of a grade between the highest-scoring Simmental crosses and the lowest-scoring Brahman and Chianina crosses. Brahman crosses had the highest condition scores, being approximately one-third of a grade higher than the lowest-ranking Chianina crosses. Differences among the sire breeds for weaning weight were surprisingly small, varying only 3 kg from the heaviest to lightest breed-of-sire groups. Angus dams had shorter gestation lengths (P less than .001) and produced calves that weighed more at weaning (P less than .001) and scored higher for conformation (P less than .001) and condition (P less than .001) score than Hereford dams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Direct and maternal genetic effects due to the introduction of Bos taurus alleles into Brahman cattle in Florida: II. Preweaning growth traits

Records of birth weight (BW), weaning weight (WW) and condition score (CS) from 1,467 Brahman and Brahman X Angus crossbred calves from Brahman and crossbred Brahman sires and Brahman, crossbred Brahman and Angus dams were collected at the Subtropical Agricultural Research Station, Brooksville, Florida, from 1971 to 1982. Best linear unbiased estimates (BLUE) of Brahman sire and dam group additive genetic effects (as deviations from Angus) and Brahman X Angus dam and calf group nonadditive (intralocus) genetic effects (as deviations from intralocus group genetic effects in the parental breeds) were obtained. Linear combinations of these were used to compute direct and maternal Brahman additive and Brahman X Angus nonadditive (intralocus) group genetic effects. The respective BLUE of these four effects were 5.99 +/- 2.08, -5.70 +/- 1.91, .52 +/- 1.81 and 2.85 +/- .72 kg for BW; 9.60 +/- 10.29, 8.76 +/- 9.47, 9.47 +/- 8.96 and 20.95 +/- 3.56 kg for WW; and -1.10 +/- .55, 1.64 +/- .50, 1.47 +/- .47 and .05 +/- .19 units for CS. Linear combinations of the BLUE of sire, dam and calf group genetic effects can be used to predict the genetic worth of crossbred groups composed of any combination of Brahman and Angus breeding. Nonadditive maternal group genetic effects were the most important factor for BW and WW, whereas nonadditive direct group genetic effects were the most important for CS.     

Direct and maternal genetic effects due to the introduction of Bos taurus alleles into Brahman cattle in Florida: I. Reproduction and calf survival

Pregnancy rate, calf survival rate to weaning and calf age at weaning of several types of crossbred cows (2/3 or more Brahman) were compared to those of straightbred Brahman and Angus cows over a 12-yr period at Subtropical Agricultural Research Station near Brooksville, FL. The purpose of this study was to determine the relative importance of additive vs nonadditive genetic effects on reproductive and calf survival traits in a population of cattle whose foundation was selected on the basis of superior reproductive performance under harsh environmental conditions. Best linear unbiased estimates (BLUE) of direct additive effect (measured as the deviation of Brahman additive breed effect from Angus) for pregnancy rate and calf age, measured as traits of the dam, were 6 +/- 3% and -7.2 +/- 2.1 d, respectively. Thus, Bos taurus germ plasm did not increase pregnancy rate but resulted in an earlier calving date. The BLUE of nonadditive (intralocus) direct genetic effects measured as deviations from intralocus group genetic effects in the parental breeds on pregnancy rate and calf age at weaning were 25 +/- 4% and -6.4 +/- 2.5 d. Nonadditive effects on pregnancy rate were the primary cause of the superior reproductive rates observed in Brahman crossbred cows. Calf survival was considered to be a trait of the calf, and BLUE of direct additive, direct nonadditive, maternal additive and maternal nonadditive genetic effects was obtained. Only maternal nonadditive genetic effects were found to have a significant effect on survival rate (9 +/- 4%).     

Effects of using sires selected for yearling weight and crossbreeding with beef and dairy breeds: birth and weaning traits

Data consisting of 948 calf records collected from 1978 to 1982 were analyzed to determine the effects of breeding methods used to improve commercial herds genetically on birth and weaning traits. Four distinct groups were used in the project: Group 1 (G1), an unselected, random mating Hereford control line; Group 2 (G2), a Hereford group using sires selected for yearling growth; Group 3 (G3), a rotational cross with Angus, Hereford, Charolais and Simmental breeds; and Group 4 (G4), a rotational cross with Angus, Hereford, Simmental and Holstein-Friesian breeds. Traits analyzed were birth weight (BW), calving difficulty (CD), percent assisted births (%AB), percent born alive (%BL), preweaning average daily gain (PWDG), relative growth rate (RGR), weaning weight (WWT) and percent weaned (%WND). The use of high yearling weight sires in G2 increased calf size (P less than .01) at birth and weaning by 8.9 and 28.1 kg, respectively, along with increased CD (P less than .01). Use of rotational crossbreeding systems increased calf size and growth from birth to weaning (P less than .01), but decreased CD and %AB (P less than .01) by .17 units and 13.5%, respectively. Including Holstein-Friesian in G4 resulted in further increases in preweaning growth (P less than .01) and calving ease was improved without affecting BWT compared with G3.     

Calving and weaning characteristics of Angus-, Gray Brahman-, Gir-, Indu-Brazil-, Nellore-, and Red Brahman-sired F1 calves

Calving and weaning data from crossbred calves sired by five Bos indicus breeds and one Bos taurus breed were evaluated. Data included calving and weaning records of F1 calves out of multiparous Hereford cows and sired by Angus, Gray Brahman, Gir, Indu-Brazil, Nellore, and Red Brahman bulls. At calving, Angus-sired calves had shorter gestations and lower (more desirable) calving ease scores and were smaller than Bos indicus-sired calves. Among the Bos indicus crosses, Gir calves had the shortest gestations, lowest calving ease scores, lightest birth weights (P less than .05), and smallest cannon bone lengths and heart girths. Nellore calves had the longest gestations (P less than .05) and largest heart girths. Calves by Indu-Brazil sires had the highest calving ease scores, highest birth weights (P less than .05), and greatest cannon bone lengths (P less than .05). Gray Brahman- and Red Brahman-sired calves were similar and intermediate for all calving characters. At weaning, Angus-sired calves had gained slightly faster than the Gir crosses and weighed more but were shorter at the hip than Gir crosses. Gir calves gained the least preweaning, weighed the least, and were shortest at weaning of the Bos indicus crosses. The Nellore and Indu-Brazil crosses were intermediate in preweaning gain and weaning weight to the Gir and the Red and Gray Brahman but were tallest at weaning. Gray Brahman and Red Brahman calves gained the most and were heaviest at weaning but were not as tall as the Nellore and Indu-Brazil.     

Maternal and reproductive performance of Brahman x Angus, Senepol x Angus, and Tuli x Angus cows in the subtropics

To determine the maternal and reproductive performance of F1 cows in the subtropics, 42 Brahman x Angus, 34 Senepol x Angus, and 50 Tuli x Angus cows were bred to Angus bulls to calve first and subsequently bred to Charolais bulls to calve as 3- to 8-yr-olds. Age at first calving did not differ among crossbred cows. Angus-sired calf birth weights were heavier (P < 0.01) from Senepol x Angus than either Brahman x Angus or Tuli x Angus cows. Weaning weights of Angus-sired calves were heavier (P < 0.01) from Brahman x Angus (213.5 kg) than either Senepol x Angus (194.9 kg) or Tuli x Angus (191.5 kg) cows. As 3- to 8-yr-old cows, calf birth weights were heavier (P < 0.05) from Senepol x Angus compared with Brahman x Angus but not Tuli x Angus cows. Weaning weights of Charolais-sired calves were heaviest (P < 0.05) from Brahman x Angus cows (268.9 kg), lightest from Tuli x Angus cows (233.4 kg), and intermediate from Senepol x Angus cows (245.0 kg). Calf crop born and calf crop weaned were lowest (P < 0.05) for Senepol x Angus cows (76.9 and 70.2%) and did not differ between Brahman x Angus (89.0 and 86.1%) and Tuli x Angus (94.7 and 86.5%) cows. Tuli x Angus cows tended (P < 0.10) to have a lower percentage of unassisted births and lower (P < 0.10) calf survival to weaning than Brahman x Angus cows but not Senepol x Angus cows. As 3- to 8-yr-olds, weaning weight per cow exposed was greatest (P < 0.05) for Brahman x Angus (234.2 kg), least (P < 0.05) for Senepol x Angus (173.0 kg), and intermediate (P < 0.05) for Tuli x Angus (209.1 kg) cows. Also as 3- to 8-yr-olds, efficiency (205-d calf weight per 100 kg of cow exposed) was similar for Brahman x Angus (42.2) and Tuli x Angus cows (40.7), and both were greater (P < 0.01) than for Senepol x Angus cows (33.8). These data indicate that, in the subtropics, maternal and reproductive performance of Tuli x Angus cows, but not Senepol x Angus cows, was comparable to Brahman x Angus cows, except for lower calf survivability and weaning weight.     

Production characters of straightbred, F1 and F2 cows: birth and weaning characters of terminal-cross calves

Records of 2,449 births and 2,120 weanings of terminal-cross calves were used to characterize maternal productivity of first- and second-generation cows from a diallel of Angus, Brahman, Hereford, Holstein and Jersey when mated to third-breed sires. Third- and later-parity cows were randomly assigned after each parturition to Charolais and Red Poll bulls in multiple-sire pastures. Calves were weaned at approximately 7 mo of age; males were not castrated. A mixed model was assumed for data analysis. Effects included in the model were breed-type of dam, cow within breed-type of dam (random), breed of sire of calf, season of record, year of record, age of dam group, sex of calf and age of calf (covariate). Age of dam groups were 4- and 5-yr-olds, 6- and 7-yr-olds, 8-, 9- and 10-yr-olds, and those greater than 10 yr of age. Dependent variables were calf weight, shoulder width and hip width at birth, weaning weight, weaning height and survival to weaning. Holstein and Holstein crosses tended to produce the largest calves at birth and weaning. Among straightbred dams, the smallest calves were born to Brahman, whereas Hereford weaned the smallest calves. Brahman-Jersey dams produced the smallest calves at birth among crossbreds; Angus-Hereford cows weaned the smallest calves. Average maternal heterosis estimates for birth weight were small and non-significant. Calves of F1 crossbred dams were 17.4 kg heavier (P less than .01) and 1.70 cm taller (P less than .01) at weaning than calves of first-generation straightbred dams.(ABSTRACT TRUNCATED AT 250 WORDS)     

Life span of beef-type Bos taurus and Bos indicus x Bos taurus females in a dry, temperate climate

Females representing Hereford, Red Poll, F1 Hereford x Red Poll, F1 Red Poll x Hereford, F1 Angus x Hereford, F1 Angus x Charolais, F1 Brahman x Hereford, and F1 Brahman x Angus breed types were evaluated from birth until 10 yr of age. Of 308 females born alive, 35.7% died or were culled because of injury, serious illness, or reproductive failure. Breed types differed (P less than .01) in total number of mating seasons per cow and total number of progeny born and weaned. Values for lifetime total number of calves weaned were as follows: Hereford, 4.54; Red Poll, 5.45; Hereford x Red Poll, 4.45; Red Poll x Hereford, 5.49; Angus x Hereford, 5.98; Angus x Charolais, 5.57; Brahman x Hereford, 6.96; and Brahman x Angus, 6.22. Brahman crosses (P less than .01) and Angus x Charolais (P less than .10) exceeded Hereford dams in lifetime total number of calves weaned but did not differ from Angus x Herefords. Analysis of the Hereford-Red Poll diallel showed no evidence of heterosis in life span traits. Results indicate that breed type was a major source of variation in reproductive life span of beef-type females. F1 Bos indicus crosses and Angus x Herefords were outstanding in longevity.     

Evaluation of birth and weaning traits of Romosinuano calves as purebreds and crosses with Brahman and Angus

The objectives of this work were to evaluate birth and weaning traits, to estimate genetic effects, including heterosis and direct and maternal breed effects, and to evaluate calving difficulty, calf vigor at birth, and calf mortality of Romosinuano as purebreds and as crosses with Brahman and Angus. Calves (n = 1,348) were spring-born from 2002 through 2005 and weaned in the fall of each year at about 7 mo of age. Traits evaluated included birth and weaning weight, ADG, BCS, and weaning hip height. Models used to analyze these traits included the fixed effects of year, sire and dam breeds, management unit, calf sex, cow age, and source of Angus sire (within or outside of the research herd). Calf age in days was investigated as a covariate for weaning traits. Sire within sire breed and dam within dam breed were random effects. Estimates of Romosinuano-Brahman and Romosinuano-Angus heterosis (P < 0.05) were 2.6 +/- 0.3 (8.6%) and 1.4 +/- 0.3 kg (4.7%) for birth weight, 20.5 +/- 1.5 (9.5%) and 14.6 +/- 1.4 kg (7.4%) for weaning weight, 79.2 +/- 6.1 (9.8%) and 55.1 +/- 6.0 g (7.5%) for ADG, 0.16 +/- 0.03 (2.7%) and 0.07 +/- 0.03 (1.2%) for BCS, and 2.77 +/- 0.32 cm (2.4%) and 1.87 +/- 0.32 cm (1.7%) for hip height. Heterosis for Brahman-Angus was greater (P < 0.05) than all Romosinuano estimates except those for Romosinuano-Brahman and Romosinuano-Angus BCS. Romosinuano direct effects were negative and lowest of the breeds, except for the Angus estimate for hip height. Romosinuano maternal effects were the largest of the 3 breeds for birth weight and hip height but intermediate to the other breeds for weaning weight and ADG. A large proportion of Brahman-sired calves from Angus dams (0.09 +/- 0.03; n = 11) was born in difficult births and died before 4 d of age. Brahman and Angus purebreds and Romosinuano-sired calves from Brahman dams also had large proportions of calves that died before weaning (0.09 or greater). Results indicated that Romosinuano may be used as a source of adaptation to subtropical environments and still incorporate substantial crossbred advantage for weaning traits, although not to the extent of crosses of Brahman and Angus.     

Preweaning efficiency for mature cows of breed crosses from tropically adapted Bos indicus and Bos taurus and unadapted Bos taurus breeds

Production data were collected on mature cows produced by mating Angus and Hereford (pooled AH), Brahman (Bh) and Boran (Br), and Tuli, a tropically adapted Bos taurus, sires by AI or natural service to Angus and Hereford cows. These cows were mated to Charolais bulls for the purpose of this study. Within each sire breed of cow, cows were assigned randomly to one of three feeding rates, 49 or 76 g of DMI/ BW0.75 or ad libitum (10 to 12 cows/feeding rate group), with weekly individual animal feed consumption recorded. Lactation yields were recorded via the weigh-suckle-weigh protocol at approximately 14, 28, 56, 84, 112, 140, 168, and 196 d postpartum for each cow/calf pair. Means for milk yield at peak lactation, total milk yields, calf birth weight, age-adjusted weaning weights, preweaning daily gain, and feed efficiency were estimated. Peak yield (kg/d) for Bh (10.3 +/- 0.36) was greater (P < 0.05) than for Tuli (9.0 +/- 0.31). Total yield (kg, 212 d) for Bh (1802 +/- 68) was greater (P < 0.05) than for Tuli (1532 +/- 59). Birth weight of AH (44 +/- 0.9) was heavier than for Bh and Br (P < 0.05). Preweaning daily calf gain (g/d) and adjusted weaning weight (kg) of Bh (813 +/- 28, 212 +/- 6.1) and Br (766 +/- 24, 202 +/- 5.1) differed (P < 0.05) from AH (589 +/- 24, 169 +/- 5.2) and Tuli (634 +/- 24, 176 +/- 5.3). Efficiency estimates (grams of adjusted weaning weight/kilograms DMI of the cow) for Bh (88 +/- 2.5) and Br (85 +/- 2.1) exceeded (P < 0.05) those for Tuli (74 +/- 2.1) and AH (73 +/- 2.1). Bos indicus breed crosses exhibited greater peak and total yield, lower birth weight, greater daily gain and adjusted weaning weight, and higher feed efficiency than did Bos taurus breed crosses (P < 0.05). Total yield, daily gain, adjusted weaning weight, and feed efficiency were higher (P < 0.05) for cows sired by bulls from tropically adapted breeds, and the peak yield was less (P < 0.10). Tuli exhibited lower total yield and birth weight than did Angus/Hereford (P < 0.05). The efficiency of crossbred Tuli cows did not differ from Angus/Hereford F1 females, but neither equaled the efficiency of crossbred cows produced using Bos indicus breeds.     

Genotype x environment interactions involving proportion of Brahman breeding and season of birth. I. Calf growth to weaning

Performance to weaning was evaluated on 489 spring-born and 416 fall-born crossbred calves of three proportions of Brahman breeding (0, 1/4 and 1/2 Brahman) over a 3-yr period. The calves were produced by appropriate matings of Angus (A), Hereford (H), Brahman (B), 1/2B-1/2A and 1/2B-1/2H bulls to Angus and Hereford cows. Interactions between proportion of Brahman breeding and season of birth existed (P less than .01) for all traits except birth weight. Birth weights of 1/4 and 1/2 Brahman calves were 1.4 and 3.8 kg heavier (P less than .05), respectively, than 0 Brahman calves. Spring-born calves that were 1/4 and 1/2 Brahman outgained (P less than .05) 0 Brahman calves 36 and 69 g/d, respectively, and were 9 and 18 kg, respectively, heavier (P less than .05) at weaning, whereas preweaning average daily gains and weaning weights were similar among fall-born cross-bred calf groups. Among spring-born calves, 1/4 and 1/2 Brahman calves were 2.6 and 6.6 cm, respectively, taller (P less than .05) than 0 Brahman calves, whereas among fall-born calves 0 and 1/4 Brahman calves had similar hip heights and 1/2 Brahman calves were 3.7 and 2.8 cm taller (P less than .05) than 0 and 1/4 Brahman calves, respectively. Conformation and condition scores were similar for crossbred groups among spring-born calves, whereas conformation and condition scores decreased as proportion of Brahman breeding increased among fall-born calves. These data indicated that genotype X environment interactions are important in beef production and increased proportions of Brahman breeding were advantageous in a spring-calving program but not in a fall-calving program.     

Breed effects on crossbred cow-calf performance

Effects of seven breeds of cow's sire and 12 breeds of cow's maternal grandsire on preweaning performance of crossbred cows and their calves were examined in data from two experiments conducted at the Roman L. Hruska U.S. Mean Animal Research Center. Data included 1,836 records over three to five parities for 516 cows by 143 sires and by 307 maternal grandsires. The statistical model fitted effects of calf sex, parity, cow birth-breeding year or cow-calf birth year, the breed effects and their interactions. Deviations of breed of sire or equivalent grandsire effects on each trait from the mean for Hereford x Angus cows ranged from -1.6 to 5.5 kg (P less than .001) for calf birth weights, -15 to 1% (P less than .001) for calving difficulty, nonsignificant for preweaning calf mortality and -2 to 27 kg (P less than .001) for calf weaning weight. Deviations were nonsignificant for conception rate and calves weaned per cow exposed to breeding, but -2 to 40 kg (P less than .001) for calf weight weaned per cow exposed for breeding, -7 to 78 kg (P less than .001) for cow weight and -20 to 2% (P less than .001) for body condition score. The advantages of Holstein and Brahman cross over Hereford x Angus cows of 23 and 13% in weight of calf weaned/cow-breeding exposure must be compared with the expected greater feed requirements from 7 or 8% heavier cows and at least 50% higher milk production, which emphasizes the need to include input measures and costs in breed evaluation schemes.     

Comparison of crossbred cows containing various proportions of Brahman in spring- or fall-calving systems: IV. Effects of genotype x environment interaction on lifetime productivity of young cows.

Lifetime productivity of young (2 to 6-yr-old) crossbred cows containing various proportions (0, 1/4, or 1/2) of Braham breeding was evaluated using 188 spring-calving and 154 fall-calving cows. Cows were mated to Limousin sires to produce 1983 through 1986 calf crops. The 1987 calf crops were produced using Limousin and Salers sires. Significant (P less than .10) genotype (crossbred cow group) x environment (season of calving) interactions were found for age at first calf and lifetime calving percentage and mature cow weight. Within the spring calving group, no differences were found between crossbred groups for age at first calf or lifetime calving percentage. However, within the fall-calving group, 0 and 1/2 Braham cows from Angus dams calved earlier than did those from Hereford dams. Age at first calf also tended to increase as proportion of Brahman increased in the fall-calving group. Within the fall-calving group, lifetime calving percentage for 0 and 1/2 Brahman cows from Hereford dams was lower than for those from Angus dams. The opposite was true for the 1/4 Braham crosses. In general, as the proportion of Brahman breeding increased, productivity, measured as weight per calf or weight weaned per year, increased; however, age at first calving increased also as proportion of Brahman increased. All spring-calving groups calved earlier in life (P less than .05) than their respective fall-calving counterparts and with the exception of the 0 Brahman groups, which were similar, spring-calving groups produced a higher (P less than .05) percentage of calves than did the fall groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of Charolais and Limousin as terminal cross sire breeds

Birth, weaning, feedlot and carcass traits were evaluated on 1,181 calves sired by Charolais and Limousin bulls out of eight crossbred dam groups (Hereford X Angus, Angus X Hereford, Simmental X Angus, Simmental X Hereford, Brown Swiss X Angus, Brown Swiss X Hereford, Jersey X Angus, Jersey X Hereford). Calves were born in the spring over a 4-yr period during which dams ranged from 3 to 8 yr of age. Charolais-cross calves were 2.7 kg heavier (P less than .01) at birth and had a 9.9% higher (P less than .01) incidence of difficult calvings and 4.6% greater (P less than .05) preweaning death loss than did Limousin crosses. Charolais-sired calves out-gained Limousin-sired calves by 31 g/d (P less than .01) from birth to weaning and were 9 kg heavier (P less than .01) at weaning. After weaning, calves were self-fed a finishing diet and slaughtered as each animal attained an estimated carcass grade of low Choice. Charolais-cross calves gained 60 g/d faster (P less than .01) than Limousin crosses, were fed 6.8 fewer d and were 17.3 kg heavier (P less than .01) at slaughter. Feed efficiency was similar for both sire breeds. On a grade-equivalent basis, Charolais crosses produced 7 kg heavier (P less than .01) carcass and had 22 g more carcass weight per day of age (P less than .01). Charolais crosses had slightly less internal and external fat. Dressing percentage was higher for Limousin cross calves (64.6 vs 63.9%, P less than .01). Longissimus muscle area and carcass cutability were similar for crosses of both sire breeds.