Sexual Revolution in the Dairy Industry
Published: November 23, 2007
Source : Stuff New Zealand
It is a statement from farmer-owned dairy genetics company LIC that it will try the new technique of sexing semen. This allows farmers to choose to produce either female or male calves. Obviously, in an industry that runs on milk, more females are desired.
The process that LIC - formerly known as Livestock Improvement Corporation - wants to try is called flow cytometry. It uses lasers to determine the mass of dna in each cell and then uses electro-magnetic charges to physically separate the X and Y sperm.
LIC genetics manager Peter Gatley has no doubt that the technology works.
"The sex-selection efficiency is well-established, but we need to measure the conception rate in New Zealand cattle," he says.
The biggest drawback identified in overseas trials so far is that a straw of sexed semen has fewer useful cells, which halves the conception rate.
But LIC has developed technology that keeps semen fresh longer and Mr Gatley feels sure this will improve conception.
It is also a costly process, reflected in the charge for the semen, which in the United States can be double the normal rate.
But Mr Gatley says we don't have a better opportunity to apply the technology - it has to come from the US but the exchange rate is, for once, on our side, dairy farmers are flush with funds and heifers are worth a lot more than they used to be.
Dairy consultant Parry Matthews thinks this won't last long, though. Once heifers can be produced virtually on demand, numbers will rise and their value will go down. This may not be a bad thing for an industry that has extremely high entry costs, with cow prices almost trebling in the past two years.
The potential benefits of sexed semen are obvious to the industry.
Female calves are easier to bear. About 10 per cent of cows experience difficulty calving a bull and only 5 per cent if the calf is a heifer.
The flow-on effect of easy calving is long-lasting. From their first lactation, cows that calve easily give more milk and they have more live calves in subsequent pregnancies. For the herd overall, there are lower vet costs and less culling is needed.
Mr Matthews says sexed semen would revolutionise the way farmers breed replacements and accelerate the improvement of productive values. The result would be more milk at a time when the world can't get enough of it.
It would allow farmers to inseminate the top half of their herd with female-producing semen in the sure knowledge they would be getting heifers.
Doing this year after year would bring a rapid increase in herd quality. At present 80 per cent to 100 per cent of a herd is mated to get enough replacement female calves.
The bottom half of the herd could be inseminated with male-producing semen from beef bulls to provide males to be grown on for the beef industry.
This would have to be carefully managed, however, he says. "If everyone rushed in and did that we'd have an oversupply very quickly."
At present, beef bulls physically inseminate dairy cows once artificial insemination has finished, often four to six weeks after the start of mating, but if artificial breeding is used it could be done at the same time, opening up an early marketing opportunity for beef exporters.
Mr Matthews cautions against seeing sexed semen as a silver bullet. "Genetics are a big part of improving milk production, but advances have to be linked with improved management, herd health and feed quality."
The key to its acceptance will be the conception rate in an industry delicately balanced around seasonal calving. "LIC will need strong on-farm trial results," he says. "If conception rates reduce there is likely to be minimal uptake of the technology except at the top end of the market."
Mr Gatley says sexed semen doesn't stop at the dairy industry.
Beef and pork industries overseas are already investing in the technology and he sees New Zealand deer farmers benefiting by being able to breed more stags for velvet production and trophy hunting.
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