Science - December 9, 2010

Breeding disease-resistant cows

The number of antibodies in a cow’s milk is partly genetically determined. Now that it is known which immune proteins protect the cow against mastitis, breeding can target resistance more precisely.

This has become clear from research by Wageningen PhD scholar Tosca Ploegaert, who found out how many different antibodies there were in the milk of 2,000 Holstein-Friesians. She researched whether the variation was genetically determined and which of these immune proteins reduces the risk of udder infections.

Mastitis
Analyses of the milk showed that it was one particular type of antibody, the subtype IgG1, which reduced the chances of an infection developing in the udder. The correlation between the number of these antibodies and the chances of mastitis was clearer in older cows than in younger ones.
Ploegaert also established that the numbers of the various antibodies in the milk of cows are partly genetically determined. Her research results therefore provide a basis for more targeting breeding of cows with better resistance to mastitis.

Uterus
Resistance to other diseases may also be traceable to the number of antibodies in the cow, says the researcher. The antibody type IgG1 seems to reduce the chances of a uterine infection in cows too. It is looking possible to use information present in the milk as the basis for selective breeding for resistance, says Ploegaert. But it is no simple matter. Further research is needed first on whether selective breeding for antibodies might not have a negative influence on other characteristics of the cow.
Ploegaert's research was an assignment for the Netherlands Udder health centre (which aims to combat mastitis), LTO Noord and the breeding organization CRV. As a follow-up to her research results, these organizations have already launched a project called Weerbaar Vee [resistant cattle]. This project is focusing particularly on the influence of management factors on resistance in cows, using measurements of antibodies in blood and milk.

Studying
Ploegaert, who is due to receive her PhD soon, is going to embark on a new student career: veterinary studies at Utrecht. 'That's what I always wanted. I missed out in the lottery for places a couple of times but now I could bypass it and get in through 'decentralized selection.'

Tosca Ploegaert graduates on 14 December with supervisors Huub Savelkoul, professor of Cell Biology and Immunology, and Johan van Arendonk, professor of Animal Breeding and Genetics.   

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