Individual lactation key to yield boost

Milk producers can and do quote the lactation yields of their dairy cattle, but a far better basis for predicting the efficiency and profitability of their enterprises would be the yield per cow per year.

"It is what you sell that is important," Colin Mason, the veterinary services manager for the Scottish Agricultural College in the south-west, said yesterday at a dairy conference in Dumfries.

The essential difference between the two methods of evaluation came with the gap between lactations. In the best 25 per cent of the dairy herds in the country, the lactations averaged 406 days, while the overall average was 424 days

That may not seem a large difference, but another speaker at the conference, Dr Alistair Macrae, head of the dairy herd health service at the University of Edinburgh, said that financial cost could be put at 3 per day.

"If the 18-day difference is multiplied up by the 3 per day and then multiplied again by the numbers of cows in the herd, that can be a considerable amount of money being lost."

Macrae said he believed this was an area where farmers could make quite a difference. There was no single factor causing the difference, but it all related to what he described as the "negative energy balance".

This had an effect on fertility and helped push out the length of the lactation, he stated.

There was no single cure, rather he urged producers to take a holistic view looking at a range of potential factors, ranging from disease through to general herd management.

As the scientists continue to try to find ways to increase efficiencies within the dairy sector, there was a plea from one research worker with Mark Dalgeish from the Moredun Institute calling for dairy farmers to provide more samples of placenta from aborted foetuses.

"Sheep producers are much better in doing this as they seem to realise we can help solve why abortions occur. I would ask that dairy farmers not only supply the aborted calf, but also the placenta from that occurrence."

He explained that abortion in cattle is notoriously difficult to identify. Some 20 years ago, less than half the cases could be attributed to any specific disease. Thanks to work being carried out at the Moredun, this percentage has risen to 60 per cent, but there was still a way to go before all the reasons were identified.He believed that vaccination programmes for diseases such as bovine viral diarrhoea were helping, but other diseases such as Infectious bovine rhinotracheitis, a respiratory disease was probably under-diagnosed.

Earlier speaking on how dairy producers could help improve the bottom line of their businesses, Mason had pointed to the considerable difference in culling rates between the top herds and the number of cows taken out of average performance ones.

While the average will see almost one-quarter of cows taken out of the herd annually, the percentage for the top herds can be as low as 10 per cent. With the cost of the rejected cows ranging from 1,500 up to 3,000, this could be a costly exercise.

The main reason for the higher rejections was fertility but this was often accompanied by other interlocking problems, he said.