3 November 2000


By Marianne Curtis

A SHROPSHIRE dairy producer has decided to use sexed semen for all his replacements after being disappointed by his best Holstein heifers producing bull calves, and their minimal value at market.

Richard Franklin of Park Farm, Aqualate, Newport, Shropshire, has been involved with Cogent from its inception and is pleased with the results from sexed semen trials he has carried out on the companys behalf.

"It is depressing when you get many bull calves from your best heifers, so I thought Id give sexed semen a go," he says.

In the first of two trials carried out at the farm, Mr Franklin inseminated 12 heifers from his 140-cow non-pedigree herd, which averages 7050 litres at 3.9% fat and 3.32% protein. Heifers used were simply the next 12 due for service, not specially selected, and were aged 16-18 months.

"Heifers had to be served within three days of each other, with prostaglandin administered twice and one insemination," he says. "Only four became pregnant and at this stage I thought, blimey, this isnt going to work."

But the success rate improved in the second trial in March this year, when 19 heifers were served during their natural heats over a three-week period. "We achieved 12 pregnancies, a conception rate of 63%, which was only slightly below our normal conception rate for the herd," says Mr Franklin.

"Considering that we were using sexed semen, I thought this was damn good." Heifers from this trial will calve in December and he is confident that calves will be heifers. The four calves resulting from the first trial – born in June – were.

Bulls used in the trials include Courier, Nightingale and Principal and although Mr Franklin is happy with Cogent bulls, he is keen to see other companies develop sexed semen technology to broaden sire choice.

He is so confident in the technology that he intends to breed all future replacements using sexed semen. "I bought 10 straws of sexed semen as part of a package when it was launched commercially at the Royal Show this year. Now availability is unrestricted, I will buy enough to cover my replacements."

Replacement rate for the herd is 20-25%, which means inseminating about 40 animals a year, says Mr Franklin. "I will select the best animals for insemination with sexed semen based on their dam and sire information. These are likely to be heifers or young cows."

Sexed semen costs £28-£35 a straw, a price Mr Franklin is happy with provided he continues to get good conception rates and, of course, heifer calves.

He is also keen to use beef bull sexed semen when it becomes available. "Hopefully this will be available next year and I will use it as long as bulls are easy calving. With Holstein bulls only worth £2-£5 currently, it makes sense."

Talking with other users of sexed semen, Mr Franklin has discovered that some have been less successful than himself. "I believe success comes down to good heat detection. Any herd with average to good conception rates should do all right with sexed semen." &#42

When conception rates with sexed semen equal those for conventional straws it gives producers confidence to use it to breed all replacements.


&#8226 Natural heat best.

&#8226 Conception rate 63%.

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