13 October 1995

Simpler with heat sync

Heat synchronisation has helped secure a 90% conception rate for one Bucks herd. Sue Rider reports

HEAT synchronisation and fixed-time AI is behind the simple management regime run by Bucks new entrants to farming, Bob and Carol Williams.

Their 121ha (300-acre) Yeat Farm, Kingswood, Aylesbury, carries 85 mainly Hereford x Friesian suckler cows and 400 North Country Mule ewes.

The Williamses finish three-quarter cross male calves on a bull beef system at 11 months and heifers off grass at 18 months. Heat synchronisation has simplified management. "It seemed sensible to lamb and calve at the same time," Mr Williams told over 70 producers at a farm walk.

"The problem early on was that the calving pattern was becoming progressively drawn out. It was intrusive in terms of our overall management approach."

Farm vet Ian Baker of Ham-pden Veterinary Hospital suggested heat synchronisation using bulls from AI to secure a more compact calving pattern. The Williamses took his advice and last year become the first users of Genuss synchronised breeding package. Cows were synchronised in two groups split according to stage of calving. Maiden heifers were also served as a separate group. Both heifers and cows were served once to AI, using Simmental, Belgian Blue and Blonde dAquitaine, after synchronisation with Crestar (see panel). Stock bulls were hired for four weeks to serve cows returning to AI.

Last year, the programme left a 73% conception rate to the AI service and an overall pregnancy rate including sweeper activity of 91%. For the 128 cows synchronised this year scanning shows 79% held to AI, with an overall pregnancy rate, including use of sweepers, of 79%.

This compares favourably with an average conception rate to first service after synchronisation of 50%, according to Crestar manufacturer, Intervet. Vet Ian Baker put success at Yeat Farm down to first-class stockmanship. "Cows must be put on a rising plane of nutrition at least three weeks before AI synchronisation, and diet and management should be unchanged for at least six weeks after service until cows are confirmed in-calf," said Mr Baker. Good handling factilities were also vital. "The animals head must be haltered and held firmly to insert the implant in the ear properly."

It was this care to cut stress that secured high conception rates to first service at Yeat Farm and an all-important compact calving pattern. But the scheme has other advantages. One is the reduced risk of introducing infectious diseases such as campylobacter and leptospirosis (causing early embryo loss or abortion) into the herd from not having to use, or rely so heavily on, hired stock bulls. Even bought-in bulls were a threat and Mr Baker advised blood testing new recruits before putting them to work.

Synchronisation has reduced Yeat Farms stock bull requirements to one for 50-60 cows.

Mr Williams also hopes that by using superior genetic sires through AI he will see improved growth rates and carcass conformation of progeny. But he admits sire selection has to be balanced between high growth rates and calving ease, especially for heifers.

The combined benefit of improved growth and carcass conformation is worth £40 a head, according to Scottish Agricultural College estimates based on experience using heat synchronisation and high genetic merit AI sires on its own suckler herd. Mr Williams hopes to see similar benefits through use of synchronisation and AI on his own sucklers.

He is confident the benefits will more than cover the £18.50 a calf cost of the programme (including drugs, implant, vet bills, AI fee and semen).

He also hopes to be able to breed heifer replacements that will be born early in the calving season so they should be two years old when they calve – again early in the season to maintain the tight calving pattern. &#42

Financial benefits of heat synchronisation and AI for a 100-cow suckler herd (£)

Superior growth of calves (extra 0.07kg-0.15kg over breed average worth 18kg to 35kg at 400 days or £25 to £45 a head)1,450

Improved conformation of calves (worth 5-15kg over breed average = £18-£52 a head)1,780

Older calvers due to tighter calving pattern (on average 13 days older worth £15 a calf)1,420

One fewer stock bull (instead of one bull for 35-40 cows, one for 50-60 cows. Bull costing £2000, annual cost is £650: Depreciation, £200; interest, £150; maintenance, £300)650

Lower calf mortality (two less calf deaths from easier calving)400

Fewer barren cows (more chance for cows to conceive)1,000

Total benefit6,700

Total cost2,000

Net benefit4,700

Net benefit a cow47

Source: Genus.