Human intervention at birth increases mortality

With the prevalence of dystocia in cows as high as 7% in herds and the costs of a difficult calving ranging from £110 to £400 depending on the severity, taking approaches to minimise calving difficulties as well as reducing human intervention is necessary to maximise health, welfare and production on farms.

This is according to SAC‘s Cathy Dwyer, who said prolonged and difficult deliveries are associated with increase offspring mortality in cattle, sheep and pigs. “Birth is an inherently risky process with nearly half of all deaths occurring on the day with overall mortality 7% in dairy cattle and 12% in sheep,” she said.

Dr Dwyer defines difficult deliveries as any birth requiring human intervention or a birth that is excessively prolonged.

“There are costs associated with prolonged pregnancies because not only do they increase offspring mortality, there can also be long-term effects on the mother from bad birth experience. .

“Reduced milk yield, increased culling rate particularly in heifers, a rise in mastitis cases and also a relationship between labour time and infertility are all long-term effects which can have severe economic impact,” she said.

But difficult calving also gives problems for the neonate too, with past research suggesting calves are three to 15 times more likely to die if there has been a calving difficulty.

Neonates may be more likely to die during assisted delivery as a consequence of asphyxia and possible injuries involving haemorrhages around the brain and spinal cord.

“Research found that birth injuries are present in 80% of lambs dieing within the first three hours after birth and in calves, 7% delivered with a mechanical calf puller have fractures. Additionally, studies have shown 35% of calf mortality were calves delivered by a mechanical calf puller,” said Dr Dwyer.

But not only is the physical damage a problem, animals assisted also take longer to reach behavioural milestones.

“Birth injured lambs and calves often have low vigour and often struggle to regulate body temperature. This in turn means they may also be slow to stand after birth and also to find the udder and suck, which in all cases could lead to weaker animals in the long run because of less uptake of colostrum,” said Dr Dwyer.

With welfare and financial implications associated with dystocia, looking at ways of preventing it is necessary. “Attention to maternal nutrition, provisions of a stress-free birthing environment and careful sire selection, particularly first time mothers can also help reduce difficulties in the short and long term.”