More than 600 cows on Troy Stuart’s farm at Framlingham are being weighed to determine if weight loss after calving is impacting negatively on their ability to return to calf the following year.

The study is using daily weight and milk production data to analyse the impact of weight change and production levels on reproductive performance.

While there are no conclusive results as yet, some preliminary findings are interesting researchers.

Early data has shown that cows conceiving from their first artificial insemination service lose less body weight than those that didn’t conceive the first time – 5% in the first six weeks compared to 8%.

The herd in 2011 lost on average 5% body weight in the first four weeks after calving and then gradually increased weight. 

In 2010 there was a 7% weight loss over the first six weeks post calving.

Not all cows followed the traditional pattern of losing weight post calving for six weeks followed by a steady incline, with some two-year-olds gradually increasing in weight, some losing weight over a longer time frame and some showing very little change.

The research is being carried out by Dr Becky Dickinson, a dairy cattle resident veterinarian employed by Melbourne University and working with Warrnambool Veterinary Clinic.

Tru-test Walkover scales have been installed at the exit of the Stuart dairy to measure the average weight of each cow as she leaves.

A Jantec identification system automatically records individual cow production and weight data and transfers the measurements to the dairy computer.

In-line milk meters at every bail on the platform give access to individual bi-daily measures of total milk volume, fat, protein and lactose percentage, and conductivity.

The study is expected to be completed at the end of 2012 and data collection is continuing.

Stuart introduced the weighing system about three years ago to enable early detection and intervention for sick/poor doing animals. 

He hoped this would improve conception rates, decrease mastitis, increase milk production and streamline individual feeding based on animal performance.

“We hoped it would pick up rapid weight loss but it varies a lot and they can lose up to 20kg between milkings,” he said.

“The DPI (Department of Primary Industries) was keen to be involved and when Becky came on board we have been trialing the cycling of cows.”

The scales are a low-maintenance addition to the farm.

“The cows walk straight over the scales so there’s no more labour involved,” Stuart added.

The farm previously used regular herd testing for production information but this proved frustrating with identification irregularities and questions about reliability of data.

DPI Livestock Industry Development Officer Sam Ellis said it was hoped the data from the study could be used by farmers to adjust their management programs to address fertility issues.

“Troy is trialing ideas such as reducing feed for animals producing large volumes of milk around drying off, and he hopes that this, in combination with products such as Teatseal, will help decrease herd mastitis,” Ellis said.

“Fertility is an issue for many farmers and this is one of the different ways of looking at finding answers.

“Hopefully after the data is analysed, farmers will be able to identify what animals are having trouble and use that information to change their management. There are no conclusive results at this stage.”

Dickinson said it was suspected that weight loss post calving was contributing to the inability of cows to become pregnant but there were no studies in Australia to confirm this.

“Overseas studies have supported this theory but there is very little live weight work in Australia. 

“A large number of herds in Victoria have a seasonal calving pattern which is different to the year-round calving seen overseas, so it will be useful to see if we can detect any link here.”

Most of the work so far has concentrated on managing and assessing weight data and weight change patterns.

“We need the data to be accurate before it can be combined with reproduction and production data,” Dickinson added.

Dickinson said that if the study showed a link between weight loss after calving and a cow’s ability to become pregnant the following season, farmers may be able to adjust their feed management systems to reduce weight loss in the post-calving period.

“We are hoping to find ways in which scales can act as a useful tool in dairy management, such as assisting in reproductive decision making, e.g. to serve or not, what semen to use, and to assist in nutrition management. Much research is still needed in this area.”

The Department of Primary Industries hosted a dairy technology field day at the Stuart farm last month.