5 September 1997

SEMEN

POOLING LIFTS FARROWING

ON-FARM semen collection and pooling of semen samples has boosted farrowing rates to 93% at Skimble Crown Pigs, Shipton.

"Semen from home-bred boars is used on the farms commercial herd, but bought-in AI is used for breeding replacements," explains Robert Beckett herd manager, at the 620-sow unit.

Performance figures for the 12 months up to January were 2.38 litters a sow a year, with 11.9 piglets born alive and a farrowing rate of 89.1% for the unit.

However, in January the unit began pooling semen samples collected from two boars. "This process improves competition between sperm and conception rates are increased," says Mr Beckett.

This has increased the farrowing rate up to 93% over the last three months which will take performance to 2.44 litters a sow a year and 12.2 piglets born alive. He explains that care is vital to maintain viability of sperm and hence sustain these conception rates.

"All equipment must be completely clean and semen is collected into a double lined plastic bag inserted into a flask," emphasises Mr Beckett.

"Our equipment is supplied by breeding equipment specialists Rotech and is all disposable so that there is no question of dirt entering the sample which could affect sperm survival," he says.

Examination

The sample is then examined for viability under a microscope in an on-farm lab and is mixed with pure demineralised water to prevent the introduction of pathogens which could again reduce viability.

A diluent is added to provide nutrients to keep sperm alive and extend the shelf life of the sample to four days.

"When mixing the diluent, water and semen temperatures of the different liquids must be within 1C (1.8F) of each other at 35C (95F) or sperm will be killed. Samples are then cooled to 17C (62.5F) to increase shelf life.

"Before artificial insemination, sows are first served naturally so we can be certain that when we inseminate 12 and 24 hours later she is definitely on heat."

Flexible plastic bottles also help us to inseminate at exactly the right time. The flexibility enables contractions in the uterine tract -which occur at the optimum point of heat for maximum conception – to draw semen in. In this way semen is taken up when the sow is at the right stage in the oestrus cycle to maximise conception rates.

"A major benefit of on-farm collection is that semen is always guaranteed to be fresh and can be examined on site before use," says Mr Beckett.

Availability

He points out that while bought-in semen can be delivered within 24 hours of a request it is difficult to get semen on a Monday. Semen from our own boars is available at the weekend and we can inseminate sows as soon as they come on heat.

"Though bought-in semen leaves the AI centre in optimum condition sometimes during transit it can be damaged by overheating or chilling effecting its viability," says Mr Beckett.

"However, sows breeding our herd replacements are inseminated using bought in semen from JSR and Cotswold. And this is vital for us to bring in new genes to maintain hybrid vigour and growth rates, he says.

Left: Semen can be collected at times when sows and gilts are showing signs of oestrus and checked for sperm motility so ensuring sows are inseminated with fresh viable semen at the right time.

ON-FARM AI

&#8226 Needs correct procedure.

&#8226 Gives control over semen quality.

&#8226 Boosts farrowing rates.

&#8226 Cuts costs.