Keeping four feet firmly on the ground

by Amina Ali

ows' feet and legs cope with a lot of stress, making them more prone to disease and reducing their functionality. U of G researchers want a measure of genetic predisposition to foot and leg disorders added to genetic evaluations of Holstein cattle to reduce the incidence of disease, decrease veterinary bills and improve animal welfare.

Animal scientists Paul Boettcher and Jack Dekkers are relating the occurrence of foot and leg disorders in dairy cattle to their underlying genetic component.

"We're looking at different aspects of foot and leg structure to identify existing problems or the potential for disease and dysfunctionality," says Boettcher.

Cows fed a diet low in fibre and high in energy to promote lactation, are susceptible to laminitis -- a disease caused by damage to the blood vessels in their hooves. Up to 30 per cent of cows have subclinical laminitis, minor bleeding that doesn't affect their movement, but another five to 10 per cent of cows with laminitis develop a limp or other clinical symptoms.

Currently, the Holstein Association of Canada evaluates dairy cows for conformation traits; physical characteristics such as height, weight and shape of the udder; and a few feet and leg traits. Boettcher's work is designed to add additional feet and leg traits that are more accurate indicators of resistance to disease than other traits are.

"These experiments will allow us to confirm the economic importance of foot and leg disorders for breeding purposes," he says.

The second stage of the research involves applying the data to select for positive foot traits and relating them to greater disease resistance. At present, the total economic value index that can be used to select genetically superior bulls and cows includes milk production, mastitis resistance and longevity criteria. The new data will be used to develop an index of traits to predict strong resistance -- a high ability to fight off disease -- in relation to the economic value of traits related to disease and functionality of feet and legs.

International interest in this work is also high. Guelph is among the first to consider the importance of foot and leg disorders for dairy selection indexes. Canada is already at the starting block with the results of this research because the Holstein Association of Canada already has an effective program to record conformation traits and the infrastructure is in place.

Canadians -- whether they're producers, agribusiness leaders or consumers -- will benefit. The health of cows gets top priority, but a reduced disease incidence also means fewer antibiotics will be used and drug resistance is kept at bay.

"If our cows build on their reputation for needing less maintenance, the Canadian agricultural industry is sure to gain," says Boettcher.

This research is funded by the Cattle Breeding Research Council, the Natural Sciences and Engineering Research Council, the Holstein Association of Canada and the Ontario Ministry of Agriculture, Food and Rural Affairs.