Evaluation of Bos indicus and Bos taurus straightbreds and crosses. III. Direct and maternal genetic effects on growth traits

Abstract

Data on Brahman and Hereford cattle and their crosses were used to estimate direct additive, direct heterosis, maternal additive and maternal heterosis effects for pre-weaning and post-weaning liveweights, average daily gain (ADG) and height at various ages. The cattle were born at Grafton, N.S.W., and raised on high, medium and low quality pastures until weaning. During the post-weaning period, the steers were grown in three environments in New South Wales, while the heifers remained at Grafton. Genetic effects were estimated by regression and the additive components expressed as deviations from Hereford effect. Weaning weight and pre-weaning ADG of Hereford calves (both sexes) were 237.8 kg and 827 g/day on high, 210.5 kg and 704 g/day on medium, and 128.3 kg and 425 g/day on low quality pastures respectively. Post-weaning ADG of Hereford steers (weaning to 36 months) and heifers (weaning to 30 months) was 296 and 240 g/day respectively. Direct heterosis was significant (P<0.05) for most traits. Estimates of direct heterosis for weaning weight were 24.9 and 20.2 kg, and for pre-weaning ADG were 79 and 68 g/day, on high and medium quality pastures respectively. Direct heterosis for ADG of steers (weaning to 36 months) and heifers (weaning to 30 months) was 91 and 76 g/day respectively. Estimates of maternal heterosis for weaning weights were 14.9, 30.9 and 37.8 kg and for pre-weaning ADG were 31 (not significant), 105 and 153 g/day, for high, medium and low quality pastures respectively. Maternal heterosis for ADG of steers (weaning to 36 months) was -47 g/day. There was a negative direct additive effect on post-weaning ADG in environments where pasture quality was good, but the effect was not significant on poor quality pasture. Maternal additive effect was negative for birth weight for high and medium quality pastures and positive for weaning weight and pre-weaning ADG on low quality pasture. The performance of untested crosses can be predicted from the estimates and models provided.

Estimates of crossbreeding parameters in a multibreed beef cattle crossbreeding project

“…These results are in contrast with estimates obtained by Dillard et al (1980), Peacock et al (1981), Roberson et al (1986), Dearborn et al (1987), Schoeman et al (1993) and Arthur et al (1994) who all reported significant maternal heterosis effects for WW. However, non-significant maternal heterosis effects for WW involving crosses between Hereford and Brahman were also reported by Arthur et al (1999) in a temperate environment.…”

“…Therefore, crossbred cows in this study did not provide a stronger in utero environment effect to increase the probability of dystocia as it is affected by calf birth weight. Studies of McDonald & Turner (1972), Dillard et al (1980), Sacco et al (1989), Van Zyl (1990 and Arthur et al (1994Arthur et al ( ,1999 are in general agreement with the existence of nonsignificant maternal heterotic effects for BW. In most investigations (Cundiff et al, 1974;Roberson et al, 1986;Dearborn et al, 1987;Elzo et al, 1990;Schoeman et al, 1993) significant maternal heterotic effects for BW have been reported.…”

“…The direct maternal effect for the Hereford was positive in some investigations (Dillard et al, 1980;Koch et al, 1985;Cunningham & Magee, 1988;Arthur et al, 1994), while it was negative in others (Gregory et al, 1978;Alenda et al, 1980;Schoeman et al, 1993;Franke, 1994), depending on the breeds it was compared with. It is also known that the Hereford is a low milk producing breed (Jenkins & Ferrell, 1992).…”

“…The direct maternal effect for the Hereford was positive in some investigations (Alenda et al, 1980;Dillard et al, 1980;Cunningham & Magee, 1988;Schoeman et al, 1993;Arthur et al, 1994;Franke, 1994), while it was negative in others (Gregory et al, 1978), depending on the breeds it was compared with. Schoeman et al (1993) also obtained a negative direct maternal effect for the Simmentaler while Cunningham & Magee (1988) obtained positive direct maternal effects for the Simmentaler.…”

“…In analysing part of the same dataset, Schoeman et al (2000) illustrated that the maternal breeding values for WW increased linearly with an increase in Simmentaler proportion in later generations. Arthur et al (1994) evaluated Brahman and Hereford cattle and their crosses on high, medium and low quality pastures and found that the Brahman maternal additive effect, compared to the Hereford, was negative on the high and medium quality pastures, and highly positive and significant in the low quality pastures. This clearly illustrated the re-ranking of breeds for crossbreeding parameters in differing environments.…”