5 September 1997

HOME BREEDING PUTS GENETICS IN THE FRAME

A closed herd policy and on farm AI are helping to reduce costs and giving greater control over breeding on one Shropshire pig unit. Jonathan Riley reports

TIGHTER control over genetics are the main advantages of breeding replacements, according to Robert Beckett herd manager at Skimble Crown Pigs, Shipton, Shropshire.

Of the 620-sow herd, 90 Cotswold sows are used to breed dam lines and 30 JSR sows used for sire lines. These sows are housed among the remaining 500 commercial sows with different coloured tags to distinguish them.

Dam line sows are AId with Cotswold 12 semen to produce replacements for the commercial herd, while Cotswold 16 Large White semen is used to produce dam line replacements. Sire line dams are inseminated with JSR semen for replacement sire line gilts or JSR Yorker Super Lean semen for replacement boar production.

The aim is to have a rapid turnover of stock to keep improving genetics which is one area that can be overlooked in herds that are operating a closed herd policy within closed herds.

This requires a replacement rate of 45% which means 22 gilts join the commercial herd, three dam line gilts and one boar line gilt join the replacement breeders.

Every month one of the units 30 boars is replaced with a seven-month-old boar from the sire line gilts. Two boars are reared as possible replacements and the best one is kept.

The young boar is then used for AI initially before joining the older boars for natural service later.

"If we werent breeding our own replacements buying in boars at this rate would cost us thousands of pounds," says Mr Beckett.

"Technically we make a profit because we are selling culls for more than it costs us to breed them.

"The main advantage is that we have total control over breeding and have a full knowledge of how gilts have been reared. Isolation and long integration periods for gilts are not needed because we know the vaccination programme imposed suits the herd."

Mr Beckett also has valuable knowledge of a gilts breeding history so that future breeding programmes can be based on detailed information. And feeding regimes to control final size can be implemented from an early age so that gilts do not grow too large, leading to excessive and costly maintenance feeding.

At weaning, commercial and potential replacement breeding gilts are reared together. The only difference is that the replacement gilts have a number tattooed into their ear to enable identification if tags get lost.

Lameness cut

At 14 weeks old replacement breeding gilts are split off and moved to solid floored housing. This eliminates the risk of lameness and foot problems that could occur on the slatted floored pens used to house replacements gilts for the commercial herd.

"At 21 weeks breeding replacements are selected by checking for 14 teats, good conformation, and strong frame and legs."

"We also look for a moderately sized gilt to ensure that high maintenance feeding later in their lives is avoided."

Growth rates from this stage are limited by switching from ad lib to 2kg/head/day of a high calcium ration which ensures that the gilt has a strong frame. The aim is to have gilts at 120-140kg for service at 220-240 days.

"Getting an even flow of gilts is a major difficulty when home breeding replacements because we cannot simply order more gilts from a breeding company.

"If we serve too high a number, pressure is put on the housing. But if too few were ready to serve, we could be forced to serve gilts too young," he says.

Planning in advance and accurate recording of returns and drop outs is vital.

"To make gilt flow more even, we have cut the average sow age down so that there is a narrower age range and their cycles are more uniform," says Mr Beckett.

He also maintains a large pool of 100 gilts to ensure there are enough available and serves maiden gilts at their second oestrus which he believes is more reliable than a first heat. &#42

Home breeding means staff have a full knowledge of the vaccination programmes and the health status of all replacement boars and gilts.

HOME BREEDING

&#8226 Cuts disease risk.

&#8226 Greater control over genetics.

&#8226 But replacement rates need careful planning.

Robert Beckett herd manager at Skimble Crown Pigs, Shropshire, says that home breeding of replacements gives more control over genetics and cuts costs.