A load of old bull or confirmation of what women have long assumed – the male is often to blame for difficulties encountered when giving birth.
The study, by PhD candidate Ms Sara McClintock, involved an investigation of the myriad factors that contribute to calving difficulty and revealed that blame could often be attributed to the father and son.
Ms McClintock found that some bulls’ calves were more likely to cause problems during birth than other bulls. She also found that another group of bulls have daughters that tend to encounter more difficulties in birthing.
Male calves were more likely than female calves to generate calving difficulties.
The study involved an analysis of data collected since 1986 by the Holstein-Friesian Association of Australia and the Australian Dairy Herd Improvement Scheme.
Ms McClintock says, “This is the first large-scale study of the genetic and non-genetic influences of calving difficulty for dairy cows in Australia, and their costs.”
“A variety of factors that potentially contribute to calving difficulty, including gestation length, calf size, month of calving, cow age, calf sex and breed of cow and bull were examined along with some genetic parameters,” she says.
As well as the influence of the bull and the sex of the calf, month of calving and cow age were also found to influence ease of calving.
Pregnancy length was also found to be an important predictor of calving problems. In fact, calves resulting from short pregnancies, although smaller, resulted in fewer calving problems and lower mortality rates.
Ms McClintock also found that crossbreeding is a good way of having an easy calving and results in very useful cows.
Calving difficulty costs Australian dairy farmers about $50 million each year and many cows and calves die every year because of it, Ms McClintock says.
“Calving difficulty needs to be seen as a high priority welfare issue, it has an impact on overall genetic progress and on our export markets.”
Ms McClintock, who completed the study for her PhD research at the Institute of Land and Food Resources, has made recommendations for improving the recording of calving difficulties and the evaluation of bulls used as sires.
She has also proposed a cost model for calving difficulty under Australian conditions.
All of her recommendations have been accepted by the Australian Dairy herd Improvement Scheme and her work has already had an impact on the farming industry.
Ms McClintock says, “The main change has been in the attitude of farmers. They have gone from thinking that nothing can be done about calving ease to knowing that they have the power to do something.”