MILK PRODUCERS can now identify which of their cows is most efficient by testing a sample of hair for leptin, a protein which regulates appetite.

A cow‘s leptin type can have a major impact on its production potential, says Merial‘s head of technical services Andy Forbes.

“Leptin is a naturally occurring appetite regulator secreted by full fat cells which tells the brain the animal no longer needs to eat.”

Merial Animal Health‘s new testing service, igenityL, identifies which type of leptin an animal has inherited from its sire and dam from a hair sample. Cows can be classified as L-tt, L-ct, or L-cc.

Those with L-tt have a weaker signal to the brain which means they eat more, perform better and are able to get through the period of negative energy balance after calving, explained Mr Forbes.

“In US trials, there was quite a significant yield advantage for L-tt cows – 1 litre/day over a lactation, but there was a marked response in the first 100 days.”

He believed testing cows will allow producers to manage their animals more efficiently to optimise production. In beef cattle the type L-cc regulates fat deposition and marbling.

To test an animal, producers simply need to take a sample of hair from the withers or tail head, making sure they include the hair follicle and that it is free from contamination.

This is sent to a laboratory in Canada and results are returned within 10 working days.