Performance of Hereford and crossbred Hereford cattle in the subtropics of New South Wales: genetic analyses of pre-weaning performance of first-cross calves

Abstract

First-cross calves of Simmental (S), Friesian (F), and Brahman (B) sires were compared with straight-bred calves of Hereford (H) sires over 5 years at Grafton, N.S.W. There was a total of 775 calves sired by 205 bulls with complete records of performance from conception to weaning. Analyses were conducted to determine sire breed and sire breed x environment effects, and to provide paternal half-sib estimates of heritabilities and genetic and phenotypic correlations. Various models were used to ascertain the sensitivity of genetic parameters to the removal of different sources of variation. Among females, S x H were heaviest at birth, while among males, B x H were heaviest. The regression coefficient of birth weight on gestation length was significantly greater for B x H calves than for other crosses. All crosses grew significantly faster to weaning and were significantly heavier at weaning than H x H calves. However, there were a number of significant interactions between sire breed and environmental variables for measures of pre-weaning growth. S x H and F x H calves appeared most sensitive to environmental variation, while B x H appeared least sensitive. The significance of this is discussed. Estimates of heritability for most traits were high. Values derived by using simple models were: gestation length, 0.68; birth weight, 0.56; average daily gain (ADG) to weaning, 0.47; weaning weight, 0.54; eyelid pigmentation, 0.50. Heritabilities of birth weight and ADG during the early pre-weaning period appeared most sensitive to the amount of environmental variation removed in the model. Gestation length was positively correlated with size at birth but negatively correlated with growth to weaning. There were large positive genetic correlations among various measures of size at birth, and among various measures of growth to weaning. When compared with ADG to weaning, weaning weight was more strongly correlated with birth weight, but less strongly correlated with gestation length. The results also indicated that selection for gain over a fixed time period, immediately prior to weaning, would be as efficient as direct selection for total ADG to weaning.

Comparison of the Brahman and Friesian breeds as sires for beef production in New Zealand

“…Calf numbers, gestation length, date of birth, and liveweight traits Gestations initiated by Brahman sires were longer than those initiated by Friesian sires, and this was consistent with results (a 9.7-day difference) from these two breeds in the large Germ Plasm Evaluation (GPE) in America ) and a 9.0-day difference in NSW (Barlow & O'Neill 1980). For birth weight, the same interaction of breed of sire x sex has also been reported before (Barlow & O'Neill 1980).…”

“…For birth weight, the same interaction of breed of sire x sex has also been reported before (Barlow & O'Neill 1980). For weights at birth, weaning, and 15-month stages, the GPE results showed that Brahman-sired calves were 3.9, 4, and 0 kg heavier than Friesian-sired calves respectively, and corresponding estimates in our study were 5.5, 4.2, and -9.0 kg.…”

“…For weights at birth, weaning, and 15-month stages, the GPE results showed that Brahman-sired calves were 3.9, 4, and 0 kg heavier than Friesian-sired calves respectively, and corresponding estimates in our study were 5.5, 4.2, and -9.0 kg. Values in the NSW experiment at birth and weaning were 2.1 and 3.1 kg respectively (Barlow & O'Neill 1980). Thus, overall, the two terminal sire breeds had different birth weights, but similar effects on liveweights from weaning to 15 months of age (relative to means at the different ages).…”

“…For pregnancy rate subsequent to a 2-month mating period, Friesian-sired heifers had a higher value (P < 0.01) as yearlings than Brahman-sired heifers (91 versus 27% in calt), but there was no significant difference in pregnancy rate in 2-year-olds as a result of breed of sire. (Barlow & O'Neill (1980) and subsequent reports cited later in this papcr). Cundiffetal.…”

Effect of errors in genetic and environmental variances on the BLUP estimates of sire breeding values

“…Henderson (1975) Bertrand et al, 1985) and 0.54 (highest; Barlow & O'Neill, 1980). Even within the same breed (Angus), h 2 ranges from 0.16 (Wilson et al, 1986) to 0.46 (Knights et al, 1984).…”