Evaluation of Bos indicus and Bos taurus straightbreds and crosses. II. Post-weaning growth, puberty, and pelvic size of heifers

Abstract

Post-weaning growth and body condition, puberty and pelvic size of 197 heifers comprising straightbred Hereford (HxH) and Brahman (BxB), first-cross (BxH) and back-cross (HxBH and BxBH) heifers were evaluated. The heifers were born over a 3 year period, and grazed improved and semi-improved pastures following weaning at Grafton, New South Wales. Prior to weaning, heifers had been reared by dams on three pasture systems (high, medium and low quality pastures). Heifers from low quality pre-weaning pasture had higher (P < 0.05) post-weaning liveweight gain than those from high and medium quality pastures. BxH heifers gained 71 g/day more (P < 0.05) than the mean gain of their contemporaries of the other genotypes, whose gains were similar, from weaning to either 26 or to 30 months of age. Liveweight at all ages was influenced by genotype x pre-weaning pasture system interaction. At 30 months of age, BxH heifers from high and medium pre-weaning pastures were the heaviest. At the same age, but from low quality pre-weaning pasture, heifers with crossbred dams (HxBH and BxBH) were the heaviest. Wither height depended significantly (P < 0.05) on the proportion of Bos indicus genes, increasing from 113.8 cm in the HxH heifers to 124.4 cm in the BxB heifers at 30 months of age. BxH heifers had a higher (P < 0.05) body condition score than their contemporaries of the other genotypes, which were in similar condition, at 26 and 30 months of age. On average (across pre-weaning pasture system), 9% of BxB heifers had reached puberty by 22 months of age compared to 62, 95, 82 and 64% (s.e.= 9) for HxH, HxBH, BxH and BxBH heifers respectively. No significant genotype differences were obtained in the height, width and size of the pelvic opening of the heifers, measured just prior to the beginning of the mating season at 26 months of age.

Genetics of heifer performance in 'wet' and 'dry' seasons and their relationships with steer performance in two tropical beef genotypes

“…We are not aware of other reports of Brahman heifers being fatter than less tropically adapted heifers. Hearnshaw et al (1994) found Brahman heifers had a higher condition score than some Hereford and crossbred heifers at weaning, but a lower condition score than Brahman · Hereford heifers at later ages. An increased ability to maintain fat in heifers through the 'dry' season could be an adaptation to tropical environments that has occurred in B. indicus.…”

Genetics of heifer puberty in two tropical beef genotypes in northern Australia and associations with heifer- and steer-production traits

“…The genotypes were not significantly different for WTCL, AGECL, CLPRIOR and CLJOIN, whereas there was a trend for BRAH to be slightly older at AGECL, with lower percentages for CLPRIOR and CLJOIN, and significantly smaller TSIZE (-1.2 mm). Increased age at puberty in Brahman heifers has been reported in other studies Bolton et al 1987;Hearnshaw et al 1994). However, Post and Reich (1980) reported from a small study of mixed tropically adapted breed groups that Brahmans had the youngest age at puberty.…”

“…The possible exception was AGECL at TOORAK, where BRAH were older (but not significantly) than at BELMONT. Hearnshaw et al (1994) found large nutrition by genotype interaction effects on the age at puberty, where Brahman growth rate did not respond to increasing nutrition compared with other genotypes and had extremely low percentages of heifers pubertal at 22 months of age in a subtropical environment.…”

“…Breed differences have been reported for the age and weight at puberty (Gregory et al 1991;Burns et al 1992;Martin et al 1992;Thallman et al 1999) and specifically, Bos indicus breeds (e.g. Brahmans) have been reported to be older at puberty than other breeds Morgan 1981;Bolton et al 1987;Hearnshaw et al 1994;Thallman et al 1999). Several studies have shown that the age at puberty was heritable in Bos taurus breeds of beef cattle (MacNeil et al 1984;Gregory et al 1995).…”

Genome-wide association study for stayability measures in Nellore–Angus crossbred cows1

“…Bos indicus and Bos indicus crossbred females are known to be slower maturing and older at the onset of puberty than B. taurus heifers (Gregory et al, 1979;Chenoweth, 1994;Hearnshaw et al, 1994;Thallman et al, 1999). Slower maturation rate in B. indicus-influenced cattle, especially straight and high percentage B. indicus heifers, often has a negative impact on the proportion of heifers that calve at 2 yr and the subsequent proportion returning to estrus during the following breeding season (Chenoweth, 1994).…”