18 September 1998


An ongoing trial should

help producers identify

factors on-farm affecting

herd longevity.

Rebecca Austin reports

COW longevity is an increasing concern for dairy producers as low milk prices and cull values mean involuntary culling must be kept to a minimum; not an easy task when average lifespan is only 2.9 to 3.4 lactations.

When Sam Gayton and Duncan Forbes set up the Kingshay Farming Trust dairy cow longevity study last November, they were warned an average survey response rate was 10%.

To date, 90% of the 1100 participating herds have filled in detailed questionnaires on management systems which will establish farming practices leading to improved longevity.

Over 110,000 cows are involved in the trial. So far 25,000 have recorded as culls during routine monthly National Milk Records testing. This indicates a potential 27% replacement rate for the study. Of the culls, 14% were cohorts. Otherwise, as the table shows, the next greatest reason for culling has been repeat breeders at 10.6% and mastitis at 8.3%.

Important issue

"The tremendous response highlights the importance of this issue to producers," says Mr Forbes, the Trusts development director. "Our own members have expressed concern and interest in the amount of time cows are lasting in their herds. This is also reflected in recent data that suggests average life span in NMR herds is between 2.9 and 3.41 lactations, depending on breed.

"Clearly herd replacement is a major issue as producers strive to control costs. The last study was carried out at least 10 years ago. Since then, milk yields have increased, genetic selection has become more important and diets have changed which means all the available information to achieve longevity is out of date."

The trials objective is to highlight the reason for culling and link that back to the farming system. To achieve this Mr Forbes and Mr Gayton, Kingshays project specialist, asked all producers to fill in a detailed form on farm and herd management.

When all this data has been keyed in they aim to provide each producer with a longevity profile which will benchmark that herd against similar herds in the trial. At the same time they will query the database to discover relationships and other factors on farm leading to increased longevity or culling within a herd.

"For example, lameness might be linked to housing or tracks; mastitis to yield level or milking routine. We want to find what makes cows last in a herd and highlight whether culling is a forced or management decision, such as genetic gain.

"The objective is to give producers greater freedom of choice in which cows they keep or cull. At the moment there is quite a lot of pressure for improved genetics using overseas breeding. This is at the expense of a high replacement rate and short herd life. We, however, are looking at the issue from a different angle," explains Mr Gayton.

The project, funded by the Milk Development Council with additional sponsorship from NMR will close in November. Initial results will be presented in January during the Cattle Breeders Conference in Cambridge.

"This project has been a great success and there is no doubt it will produce good results which farmers can apply practically to their own herds," says Mr Forbes. &#42


l1100 participating herds.

&#8226 90% response rate.

&#8226 Results in January.

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