Genetic and environmental effects on early growth and performance in purebred Holstein, Jersey, and reciprocal crossbred calves

For this designed experiment, Holstein × Holstein (n = 28), Jersey × Jersey (n = 10), Holstein × Jersey (n = 15), and Jersey × Holstein (n = 15) bull and heifer calves were compared for body weight (BW), dry matter intake, feed efficiency, hip height, BW gain to 42 and 56 d, and days to weaning from birth to 8 wk. All traits were examined for purebred, maternal, and heterotic genetic effects. Purebred genetic effects significantly favored the Holstein breed for BW, dry matter intake, hip height, and BW gain to 42 and 56 d. Heterotic genetic effects were present for dry matter intake and hip height. Calf sex affected BW and BW gain to 56 d. Our results indicate that early calf growth is influenced primarily by purebred effects favoring the Holstein breed and to a lesser extent heterosis.