Heterosis retention for birth and weaning characters of calves in the third generation of a five-breed diallel2

Abstract

Data were 876 birth records and 727 weaning records of straightbred and F3 crossbred calves produced in the third generation of a five-breed diallel. Among straightbreds at birth, Holstein calves were heaviest and widest at the shoulders and hips. Jersey calves were lightest and narrowest at the hips, and Brahman calves were narrowest at the shoulders. Holstein crosses tended to be larger at birth than crosses among other breeds. Among straightbreds at weaning, Holstein calves were heaviest and tallest, and Hereford calves were lightest and shortest. Angus calves had the highest survival to weaning rate, and Holstein calves had the lowest survival rate. Among crossbred calves, Holstein crosses tended to be larger at weaning. Estimates of average heterosis retained for birth characters were not significant. Significant breed mean heterosis retention was observed for birth weight, shoulder width, and hip width of Hereford calves and for shoulder width and hip width of Holstein calves. Estimates of average heterosis retained for weaning weight and height were 6.1 kg (P less than .01) and 1.02 cm (P less than .05), respectively. In general, estimates of specific and average heterosis retained for survival to weaning were nonsignificant. Significant breed mean heterosis was observed for weaning weight and height of Brahman, Hereford, and Holstein calves and for survival to weaning of Hereford, Holstein, and Jersey calves.