Sensors, blood profiling hone in on battle against calf loss

Paving the way for such research has been developments in automated sensing devices, which allow social behaviour in cattle to be accurately and objectively measured.

Researcher Rory Nevard said calf mortality was a key issue for the northern Australian beef industry, resulting in significant reductions in productivity, economic profitability and poor animal welfare outcomes.

Calf loss during the first two weeks of life alone has been estimated to cost the northern cattle industry more than $54 million annually.

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Research is being undertaken at the Charles Sturt University farm in Wagga Wagga looking at whether a relationship exists between cows with high blood prolaction and good cow-calf interaction.

Prolactin is a protein hormone secreted from the brain and is important to both lactation and maternal behaviour.

Dr Nevard, from the university's School of Animal and Veterinary Sciences, gave an overview of the research at the 2021 Graham Centre Livestock Forum, held virtually last month.

He said calf wastage was typically hard to objectively quantify because in northern settings, cows were only brought in once or twice a year.

"We don't have a lot of information about what is going on to cause losses between pregnancy testing and subsequent weaning," he said.

"However, in similar situations in the United States, where a lot more research has been done, they found the first few days of life is where the greatest losses occur and maternal behaviour has been shown to be a critical determinant."

Those large-scale US studies found 57.4 per cent of calf loss occurred within 24 hours of calving, with almost 75pc of total deaths occurring within one week of calving.

Dr Nevard explained maternal behaviour was genetically controlled, so there was the potential to identify cattle with superior maternal behaviour to reduce calf wastage.

What makes a good mother was a very broad question, he said.

It depends on the breed, the climate and environment the cows are in and production systems.

A Bos indicus cow and calf will have completely different requirements for being a good mother than Bos Taurus dairy cows.

A key challenge associated with behavioural traits is the difficulty in measuring and quantifying them.

"Recording maternal behaviour on a large scale, particularly in extensive production systems, is often impractical and there is a need to explore alternative traits that are easily measured and could be used as indicators of maternal behaviour," Dr Nevard said.

"Blood hormonal profiles offer a promising opportunity as an alternative trait. Past studies have demonstrated the influence of prolactin during the periparturient period is a crucial determinant of maternal behaviour.

"Of particular interest is that high prolactin during late gestation in mammals can program an offspring's ability to become a good mother."

In this research project, proximity logger collars are recording interactions between cow and calf.

When cows have calved, the collar is fitted around the neck of the cow and the calf. Blood collection for serum prolactin assay will take place on the day of calving, and then every fourth day until two weeks postpartum.

Cows and calves will wear the collars for two weeks post calving.

Calf hydration status, blood Immunoglobulin G levels, and body weight gain will be assessed during the experimental period.

The proximity logger data will be compared with cow and calf measurements to determine if there is any probable association between the hormone prolactin and cow maternal behaviour.

Dr Levard said the research offered several opportunities for genetic selection for improved prolactin, or alternatively management-based interventions that ensure high prolactin levels during late gestation.

Future work could then look at the behaviour of subsequent generations, he said.

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