19 November 1999

Dont write off synchronised breeding

DISMISSING synchronised breeding of dairy cows to tighten calving intervals because of low pregnancy rates could be misplaced after a study revealing a possible £50-£60 a cow average benefit on south east herds.

Researchers at ADAS Bridgets studied 220 cows treated with Intervets Intercept planned breeding regime and an equal number of cows bred normally on eight farms. They found that despite a 10% lower pregnancy rate of 40%, the Intercept treated cows were all served in the desired period compared with 70% of the untreated cows.

This reduced the calving to conception interval by an average of 15 days to 91 days for Intercept treated cows. There were also 6% fewer treated cows barren at 150 days after calving, according to a report in the Vet Record, Nov 6. Most benefit was seen in herds with lower submission rates to first service.

Intervets Ian Mawhinney estimates the saving in calving interval and cull cows is worth £50-£60 a cow in the average herd at current values. Costs of treatment will vary depending on the number of vet visits needed to inspect and inject cows, but will not outweigh these potential benefits, he adds.

He recommends the treatment as suitable for herds with a tight calving pattern wishing to breed cows in a reasonable time period – particularly those wanting to improve submission rates.

The companys planned breeding programme, Intercept, involves giving cows a gonadotrophin releasing hormone (GnRH), prostaglandin seven days later and then a second dose of GnRH 48-60 hours later.

Cows are then served to fixed time AI 68 to 72 hours after the prostaglandin injection. "But 10% of cows are seen on heat before the final injection and can be served and given the second GnRH dose at the time of insemination." &#42