Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: growth of first-cross calves to weaning

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Abstract
Thirty-one Simmental (S), 33 Friesian (F), 27 Brahman (B) and 30 Hereford (H) sires were mated to Hereford (H) females over 3 years at Grafton to evaluate the performance of first-cross calves in the subtropics of New South Wales. An average of four calves was produced by each sire. Gestation lengths of B x H and S x H calves were 8 and 3 days longer and those of F x H calves were 2 days shorter than in H x H calves. There was a significant genotype x sex interaction for birth weight. Among male calves B x H were heaviest at birth, while S x H were heavier than H x H. There were no significant differences between genotypes among female calves. When adjusted to a constant gestation length B x H males were still heavier at birth. Crossbred calves grew faster to weaning than Hereford calves. Advantages in liveweight at weaning were 12.4 kg (B x H), 15.1 kg (S x H) and 16.3 kg (F x H), when a common conception day was assumed. Crossbred calves had greater body dimensions at birth, and generally had greater increases in body dimensions between birth and weaning. Differences in body dimensions were not entirely accounted for by differences in weight. Brahman x H calves had approximately twice as much eyelid pigmentation as calves of other genotypes. Male calves had 1.4 days longer gestation length, 2.2 kg heavier birth weight (genotype x sex interaction significant), and 60 g day-1 faster growth rate to weaning than females.