1 March 2002

What is the best way to raise conception rates?

By Wendy Owen North-east correspondent

ALARMING figures which show that dairy cow conception rates have dropped to just 40% are concerning producers. But while some experts believe a feeding solution is possible others recommend targeting problem animals.

This debate was the subject of a Milk Development Council seminar in Penrith, Cumbria. At the meeting, Dutch veterinary expert Dirk Zaaijer said if producers spent more time observing cows and concentrated on matching the diet to the exact stage of lactation, herd fertility should automatically improve.

He did, however, acknowledge there could be the exception of a few isolated cases. The blanket use of hormones to solve reproductive disorders could actually cause more problems in the long term, he warned.

But George Mann, who researches dairy cow fertility at Nottingham University, outlined a number of factors which influenced calving rates and stressed it was important to look at the whole picture.

"Over the past 20 years, the calving rate has declined from 60% to 40%. If this carries on, only one-fifth of inseminated cows will calve by 2020. That is already happening in some US dairy herds.

"It is too easy to blame increasing milk yields for this decline in fertility, although that is a factor, along with greater average herd size and more cows/stockman.

"There is scope for improvement and we are researching the use of milk progesterone testing as a useful tool in improving conception rates."

The tests are used to target cows for heat detection and AI and can help with decisions on infertility treatments.

Whole-herd progesterone testing was a good way of removing the guesswork and finding out what was happening inside the cow, said Dr Mann.

But he reported that uptake by producers had been slow, mainly because testing was labour intensive. Until more practical methods were found, it had mainly been used to target individual problem animals.

Dr Mann also outlined Norwegian research which had been making progress towards the selection of animals for high fertility. However, heritability for these traits was low and it was difficult to get a clear picture in trials as there could be a number of reasons why a particular animal had a long calving interval.

But Dr Zaaijer stressed getting the basics of feeding cows correctly at all stages of lactation was vital, but many producers he visited in his role as a consultant had failed to do so. "Dry cow nutrition is often neglected, which has a detrimental effect on fertility after calving.

"The most important thing is good stockmanship. Observe signals the cow is giving you as you go about your work and write them down every day. Do 80% of your animals have a shiny coat? If not, there is something wrong with their diet and you need to go back to your nutritionist and alter the ration."

Audience member Mike Harrison, who works at Greengill Farm, Penrith, found milk progesterone testing took up too much time. He also agreed with the rest of the audience that it had become difficult to obtain independent advice on feeding to help formulate cow diets.

"Big companies rule the world. It is hard to get an unbiased opinion, but at the same time I think it would be difficult for an individual to make a living as an adviser the way things are now," said Mr Harrison. &#42

&#8226 Get basic feeding right.

&#8226 Observe cows closely.

&#8226 Progesterone tests useful.

Fertility can often be overcome by correct feeding, says Dirk Zaaijer.

Milk progesterone testing helps target problem cows, says George Mann.