Dairy lactation trials Two major dairy cattle tests are being undertaken at Tokanui Dairy Research Farm to try and understand the mechanisms that regulate milking persistency. A cow reaches peak lactation at four to six weeks after calving, then there is a gradual decline of milk production.
In one trial, scientists took mammary gland biopsy samples at two stages of lactation, one at the peak stage and one later. It is hoped that lab analysis will provide some clues about the divergence in milk yield between the two sample groups.
Another trial was based on overseas reports that persistency can be improved by carrying out frequent milking in the early stages of lactation, then reverting to twice-daily milking.
In this trial, 10 cows had half the udder milked twice a day and the other half four times a day for a period of two weeks after calving. This method will eliminate a lot of potential for variability, such as nutrition and genetics, as the two samples for comparison are taken from the same animal.
So far, results have shown that some areas of mammary tissue are more active than others, and this varies between animals. Several known cell signalling pathways are being targeted to try to determine how inactive, or less active, tissue could be ‘switched on’ to improve milk production.
Research is focusing on understanding the molecular mechanisms that regulate lactation persistency One trial compares samples from cattle at peak and post-peak milking Another trial compares samples taken from both halves of the udder, where each half has been milked at a different frequency