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Factors Affecting Weight and Score of Crossbred-Type Calves

1964; Oxford University Press; Volume: 23; Issue: 1 Linguagem: Inglês

10.2527/jas1964.23121x

1544-7847

E. H. Vernon, W. R. Harvey, E. J. Warwick,

Genetic Mapping and Diversity in Plants and Animals

Records accumulated among Brahman-Angus and Africander-Angus crossbred-type calves during the period 1932–1957 at the Iberia Livestock Experiment Station, Jeanerette, Louisiana, were studied to determine environmental effects and differences among crossbred groups for calf weights and scores. An average difference of 43 lb. in Brahman-Angus crossbred-type cattle was found between bull and heifer weights at 180 days. These differences were greater in years with above-average weights and multiplicative factors appear to be satisfactory in adjusting for sex effects. Month of birth significantly affected birth and 180-day weights as well as conformation score. Earlier born calves weighed more and scored higher than later born calves. Calves from 3-year-old dams in the Brahman-Angus group were 37 lb. lighter at 180-days and those from 4-year-old dams were 15 lb. lighter at 180-days than calves from dams 5 years old and older. These age-of-dam effects, however, differed markedly in two production-level groups formed by arbitrarily dividing years into two groups based on calf weights. This strongly suggests that a regression type of adjustment should be made for age-of-dam effects, rather than a multiplicative factor type. As an example, 180-day weights of calves from 3-year-old dams could be adjusted to a 5-year-old dam basis by taking 35% of the 180-day weight of the calf and adding 257 lb. to that amount. Calves produced by mating F1 cows to Angus sires weighed more (398 lb.) at 180 days than did calves produced by any of the other 25 crossbred groups considered in the Brahman-Angus. In reciprocal matings, the F1 dams produced calves which weighed more at 180 days than did either Angus (52 lb. more) or backcross (11 lb. more) dams. Calves resulting from inter se matings in the 25%, 37.5% and 50.0% Brahman groups generally weighed less at 180 days than did calves from the Angus x F1, the backcross x backcross or the F1 x F1 matings, respectively. Differences among crossbred groups in weaning score in the Brahman-Angus closely paralleled the differences in 180-day weight. In this group, calves out of F1 dams weighed from 2 to 5 lb. less at birth than did calves out of either Angus or backcross dams. Brahman-Angus crossbred-type calves averaged 31 lb. heavier at 180 days and approximately one-sixth of a grade higher on beef conformation score at weaning than the Africander-Angus.