8 August 1997

GOING TOWARD LONGER LIVES

Computerised mating can save valuable time in selecting the right sire for each cow. Jessica Buss reports

SELECTING sires based on linear traits of both bull and cow should help breed cows with greater longevity.

Thats the view of dairy manager for Firle Estates, Roy Williams. He has managed the herd for two years and wants to fine tune breeding by mating cows to bulls with good production potential that will also improve functional type and longevity.

According to Mr Williams, the herd needs a good capacity cow with strength in the chest, which can withstand large herd management and has feet and legs which will allow it to meets its genetic potential.

Mr Williams also aims to increase yields from 6700 litres to 8000 litres but maintain a high yield from forage. To help achieve this, he has chosen to use the Holstein Friesian Societys Select-a-Bull computer mating service.

HFS head classifier Jim Westaway explains that this is a mating service for both pedigree and non-pedigree breeders who aim to improve functional type – particularly legs, feet and udders.

"Once the producer has stipulated his breeding criteria, a short list of sires is produced by the computer. Then each cows linear profile is mated to the sire which best complements that profile. The computer takes the spade-work out of looking through AI brochures and assessing all cows weaknesses," says Mr Westaway.

The 160-cow herd at Charleston Farm, Firle, West Sussex is pedigree, but Mr Williams has not evaluated type before. For the first run of Select-a-Bull, Mr Williams has chosen 71 cows for linear type trait assessment. These are the cows that he wishes to breed heifers from. In the future only first lactation heifers will need classifying for the cows will already have assessments.

The traits assessed by the classifier include six body traits, three for legs and feet, and seven for the mammary system.

"It is difficult to look at your own cows objectively when you see them every day," adds Mr Williams. The classifier can pinpoint out their weaknesses.

The linear trait data is entered on a handheld data recorder and then downloaded into the classifiers computer. The parentage of each animal and pedigree index data is downloaded from HFS records to prevent inbreeding.

Suitable bulls are then chosen. This is based on the farms production criteria using an extensive sire database, and the preferred selection highlighted for mating to the cows.

The breeder can also alter the ideal type profile to breed a specific type of cow for the herd. When the best sire is selected for each cow the semen needed can be ordered from the supplier.

In this case, however, Mr Williams had 170 straws of semen from six sires in his DIY AI flask to use, so only these bulls were matched to the cows.

The programme gives Mr Williams a first, second and third choice sire showing the relative type improvement and the predicted PIN of the calf.

"There may be little difference in the improvements predicted between first and second or third choice sire. Then a second or third choice sire can be used to balance semen use with supply, or to achieve a higher predicted PIN calf," says Mr Westaway.

&#8226 Linear assessment costs £3 a cow or heifer. Select-a-Bull costs £1 for each cow selected for breeding replacements.n

Roy Williams (left) is using HFSs Select-a-Bull service to find the best sire for each cow which is suitable for breeding replacement heifers.

Jim Westaway (left) assesses cows for 15 different traits to find the ideal sire.

SELECTINGSIRES

&#8226 Identify cows for breeding.

&#8226 Assess cows on linear traits.

&#8226 Set production criteria for bulls.

&#8226 Match cow linear to suitable sire.