A preliminary study of Dystocia in Belgain Blue x Friesian heifers and other cross breeds.

Abstract

Calving data were collected on 17 Belgian Blue x Friesian (BBF), 10 Limousin x Friesian (LF), 8 Simmental x Limousin x Friesians (SLF) and 4 Charolais (C) heifers. The animals were bred by artificial insemination (AI) to one Limousin bull to calve at 2 years of age. The BBF and LF were bucket reared while the SLF and C were single-suckled to 7-8 months of age. Subsequently, all animals were treated similarly. Because of the small number of C involved, information on these was excluded in breed comparisons but was included for correlations between various traits. The main findings were: • The mean liveweights at calving were 524, 521 and 583 kg for BBF, LF and SLF animals, respectively. • Measurements taken during late pregnancy showed that SLF had significantly greater wither height, pelvic height, pelvic width, cannon bone length and hind-quarter roundness than the BBF and LF which were the same. These differences tended to reflect the liveweight differences recorded. • Chest width of both the SLF and BBF was greater than for LF indicating, that despite having similar liveweights, the BBF had a wider chest than the LF. • Gestation length was longer for the SLF (294 days) than for the other two breed types (290 days). • There was no significant effect of heifer breed type on calf birth weight but when expressed as a proportion of dam liveweight, birth weights of the BBF were greater than SLF with no significant difference between the LF and the other two breed types. • Calving difficulty score was significantly higher for BBF than for SLF with LF intermediate. The incidence of caesareans was 29%, 10% and 0% for the BBF, LF and SLF, respectively. Cow internal pelvic height was greater for the SLF than for the other two breed types but there was no effect of breed type on pelvic width. Pelvic areas were 272 cm2 for BBF, 279 cm2 for LF and 285 cm2 for SLF. Those were not significantly different. • There was no significant relationship between cow liveweight or external skeletal measurements and calf birth weight. • Calf birth weight was positively related to cow internal pelvic width and pelvic area. • There was a close relationship between the birth weight of calves and calf chest girth, hind-quarter roundness and calf head circumference. • Calving difficulty score increased with increasing birth weight and particularly as birth weights expressed as a proportion of cow weight increased. • Increased hind-quarter roundness and increased chest girth of the calf were associated with increased calving difficulties. • Calving difficulty score decreased as cow size increased. All correlations between calving difficulty score and external skeletal measurements were negative but only those with withers height and pelvic height were significant.