Charolais Research Articles

Breed means for average daily gain, feed conversion and intake of beef bulls during postweaning feedlot performance tests.

Comparisons of ADG, feed/gain, 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 1967 to 1986 of 3,661 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 1967 to 1976 (P1) (n = 1,654) and 1977 to 1986 (P2) (n = 2,007). Breeds in P1 were Hereford (HH), Angus (AN), Charolais (CH), Polled Hereford (HP) and Santa Gertrudis (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 (all P less than .01 except for initial age on ADG in P1). 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, HP, 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.(ABSTRACT TRUNCATED AT 250 WORDS)

ENERGY METABOLISM AND THERMOREGULATION IN THE NEWBORN CALF; VARIATIONS DURING THE FIRST DAY OF LIFE AND DIFFERENCES BETWEEN BREEDS

Rectal temperature (RT) and heat production (HP) of 10 Holstein–Friesian (HF), 10 Salers (S) and 7 Charolais (CH) calves held in a 10 °C environment were measured continuously during the first day of life. Rectal, skin and haircoat temperature, as well as haircoat weight, were determined in 31 other calves (11 HF, 11 S and 9 CH). Basal metabolism was measured in 18 other newborn calves (9 HF and 9 CH). Heat production decreased curvilinearly and reached a plateau 15 h after birth, when the haircoat was dry. Charolais and Salers calves could maintain their RT in spite of an HP 15 to 10% lower than that of HF calves. This difference could be explained neither by the lower physical activity of CH and S calves nor by better haircoat insulation. It seemed to result mainly from a lower metabolic rate of beef calves, according to the 13% lower basal metabolism of CH calves. These latter were also handicapped by slight acidosis, reduced physical activity, and delayed immunoglobulin absorption, which may contribute to their higher early postnatal mortality and morbidity. Key words: Calf, newborn, breed, energy metabolism, thermoregulation

Relationships Among Scrotal Circumference and Certain Performance Traits of Beef Bulls During Postweaning Feedlot Performance Tests

Knowledge of the relationships between scrotal circumference and performance traits can give cattlemen important information for selecting superior sires. Data were collected from 673 individually fed bulls in the University of Arkansas beef-bull performance tests from 1983 through 1986 to evaluate these relationships. Three Arkansas locations, including Fayetteville (1 test/yr), Monticello (1 test/yr), and Hope (2 tests/yr), and 10 breeds were included in the analysis. The dependent variable, scrotal circumference (SC), was analyzed using a model including test number, breed, initial weight (WTI), initial age, backfat thickness (BF), feed conversion (FCONV) and average daily gain (ADG). Scrotal circumference, WTI, BF, ADG, and FCONV were measured in cm, kg, cm, kg and as kg feed/kg gain, respectively. Test number accounted for the variation associated with year, location and season. Breeds evaluated were Simmental (SM), Angus (AN), Hereford (HF), Maine-Anjou (MA), South Devon (SD), Polled Hereford (PH), Charolais (CH), Santa Gertrudis (SG), Brangus (BR) and Beefmaster (BM). Least-squares means indicated that the SM bulls had larger SC (P<.05) than SD, PH, CH, SG, BR, and BM. Conversely, the BM bulls had smaller SC (P<.05) than SM, AN, HF, MA, SD, PH, and CH bulls. The partial regression coefficients of SC on WTI, BF, and ADG were .017, 1.459, and 3.328cm per unit of measurement, respectively. These data suggest that bulls that are heavier at the start of the test, have higher ADG and greater BF tend to have larger SC.

GENETIC PARAMETERS FOR MATERNAL TRAITS IN BEEF CATTLE

Direct (D) and maternal (M) parameters for birth weight (BW), preweaning gain (WG) and calving ease (CE) were estimated for Angus (AN), Hereford (HE), Charolais (CH), Simmental (SM) and Shorthorn (SS). Data for the study were collected by Agriculture Canada from 1973 to 1983 for use in the National Sire Monitoring Program. Variances were estimated for each breed by a modified Method IV applied to a sire-maternal grandsire model with herd-year-seasons and age of dam × sex of calf as fixed effects. Genetic correlations (D/M) between D and M effects for WG in AN, HE, SS, CH and SM were −0.54, −0.42, −0.14, −0.26 and −0.45, respectively. Corresponding estimates of direct heritability for WG were 0.39, 0.30, 0.39, 0.27 and 0.43 and of maternal heritability 0.21, 0.27, 0.26, 0.16 and 0.20. Estimates for BW were similar to those for WG. Estimates of the D/M correlation for CE were −0.43, −0.15, −0.32, −0.74 and −0.27, of the direct heritability 0.28, 0.17, 0.19, 0.33 and 0.21, and of the maternal heritability 0.22, 0.13, 0.19, 0.23 and 0.27 for AN, HE, SS, CH and SM, respectively. Genetic trend and the introduction of new genetic lines are expected to have influenced parameter estimates. Due to negative D/M correlation estimates and moderate maternal heritabilities, selection for both the D and M components of maternal traits is advised. Key words: Variance, direct, maternal, heritability, genetic correlation, beef cattle

ESTIMATION OF GENETIC TRENDS FOR CANADIAN STATION-TESTED BEEF BULLS

Data collected from Canadian central test stations were used to obtain estimates of genetic progress for test station average daily gain (ADG-T), height at hooks (HH), ultrasonically measured backfat thickness midway between the 11th and 12th ribs (FAT) and scrotal circumference (SC). Where possible, records for preweaning average daily gain (ADG-W) from the Federal-Provincial Herd Record of Performance program were obtained for tested bulls. Estimated breeding values were regressed on year of birth to obtain estimates of genetic trend for each trait, for the six principal breeds enrolled in the testing program: Aberdeen Angus (AA), Charolais (CH), Hereford (HE), Limousin (LM), Shorthorn (SH) and Simmental (SM). Estimated trends were generally significant with the exception of those for the LM breed, and the trait of SC. For FAT, trends were generally positive for the exotic breeds, and negative for the British breeds. Significant positive trends were observed for HH, ADG-W and ADG-T for most breeds. Examples of estimated genetic trends, for the HE breed, were 0.0022 kg d−1 yr−1, 0.0023 kg d−1 yr−1, 0.090 cm yr−1 (NS), − 0.029 mm yr−1, and 0.009 cm yr−1 (NS), respectively, for ADG-W, ADG-T, HH, FAT and SC (NS = not significant). Most estimated trends were low, in the order of 0.1 to 0.5% of population mean per year. Key words: Genetic trend, central test stations, beef bulls

Growth of bovine tissues 1. Genetic influences on growth patterns of muscle, fat and bone in young bulls

AbstractCarcass composition and growth patterns for muscle, fat and bone were compared among 277 young male progeny of eight sire breeds, serially slaughtered at 300 kg live weight, 12 months and 15 months of age. The sire breeds were Simmental (SIM), Charolais (CHA), Danish Red and White (DRK), Romagnola (ROM), Chianina (CHI), Hereford (HER), Blonde d'Aquitaine (BDA) and Limousin (LIM). Tissue growth patterns among breeds were examined by regression estimates from the allometric growth equation (Y = axb) and compositional differences were estimated from the intercepts. No significant sire breed differences were found in the regression of muscle, fat or bone on various size dimensions. In regressions involving fat, however, the fattest (HER) had higher regressions and the leanest (BDA) fattened more slowly relative to muscle and bone growth. Breeds differed significantly in amount of muscle, fat and bone when compared at standard weights.Sire breed ranking for muscle at common bone weights was LIM, BDA, CHA, SIM, HER, ROM, DRK and CHI, while at common carcass weights the ranking was BDA, CHA, LIM, CHI, ROM, SIM, DRK and HER, reflecting differences in fatness. Minor changes in ranking occurred when comparisons were made at a common live weight reflecting differences in dressing percentage. For fat at standard muscle, carcass or live weight the breeds ranked HER, LIM, DRK, SIM, ROM, CHA, CHI and BDA.