We don’t like the thought of disposing of a healthy animal because we see it as our job to look after animals
Increased selective breeding means herd quality is improving at a greater rate, believes Stephen and Graham Wyrill.
Sexed semen plays a significant role in the management of the Wyrill family’s Holstein milking herd at East Appleton, Richmond. Having used the product since it was introduced in the late 1990s, Graham Wyrill says he is happy with the average 65% conception rate he achieves from DIY AI.
The key to success is in following breeding company advice, he says, and he generally uses 1.5-2 straws for each heifer calf produced.
Sexed semen offers several advantages over the conventional product, according to Graham, who runs Leazes Farm with his father, Ken and brother, Stephen.
“I like the fact that we are only sourcing replacements from the top 35 cows in our herd,” Mr Wyrill says. “It is easy to pick out 20 or 30 good cows from a herd of 120, but without sexed semen we would be forced into selecting replacements from lower quality animals.”Longevity
With the best cows averaging seven or eight calves over a lifetime, doubling the number of heifers they produce increases herd longevity, he adds. The policy reduces replacement costs and maximises yield potential. More than a dozen cows in the herd were born before 1996 and have averaged 10,000kg-plus.
Cows not inseminated to sexed semen are put to Blonde bulls with Blonde cross bull calves born on the farm sold at just over a week old, while heifers are turned out in the summer and finished during the autumn.
Calf value is part of the output of the dairy herd and producing beef crosses, rather than black and whites, makes an important contribution to farm income. Mr Wyrill says the farm does not have the facilities to keep bulls and the family believes castration slows growth rates to an unacceptable level.
“It costs about 30% more for sexed semen. However, instead of getting large numbers of black-and-white bull calves worth between £40 and £50, we improve our turnover by rearing more beef animals, which have a value of between £200 and £250,” he says.
The odd bull calf that results from using sexed semen is tolerated, because of the general benefits of the system. At Leazes, only five or six accidental bull calves have been born over the past decade.
Mr Wyrill refutes the argument that the choice of available bulls is limited when opting for sexed semen. “Genetic progress will be slower if you produce large numbers of bulls from your best cows. Paying high prices for semen and getting a batch of bull calves does not make economic sense.”
Although it may not be a financial consideration, the Wyrills also say they prefer to avoid the task of destroying black-and- white bull calves at birth.
“We don’t like the thought of disposing of a healthy animal because, as farmers, we see it as our job to look after animals,” says Mr Wyrill. “Sexed semen also gives us the pleasure of seeing heifers out of only our favourite females coming into the herd and making their mark on our cow families.”
Heifers are put to the Blonde d’Aquitaine stock bull for their first calving so the Wyrills can assess whether they are worthy of producing herd replacements before going to the expense of using black-and-white semen on them.
Also, they are never served before 18 months, because the Wyrills prefer them to have a chance to grow properly, before they start milking. They also aim for heifers to reach a decent size before mixing with cows, to reduce bullying.
MAXIMISING SEXED SEMEN BENEFITS
Cogent breeding specialist Barry Lawson says correct handling of sexed semen is vital, along with ensuring cows are in the correction condition before service.
“Use identification tags to locate straws – never take out a straw to look at it and then put it back, and always use tweezers,” says Mr Lawson. “Don’t hold the canister high in the neck of the flask for more than five seconds, and remember to flick the straw, to remove any trapped liquid nitrogen.
“Ideally, use a thermostatic electric thawer to thaw at 37C for 40 seconds. Dry the straw thoroughly, as water will kill sperm.”
Mr Lawson advises users to pre-warm the AI gun to 37C and keep it insulated until ready to use.