Better models, better genetics
Dairy evaluation procedures are being improved by researchers
by Amina Ali
new procedure developed by U of G researchers is helping to improve the accuracy of dairy cow genetic evaluations.
Some of the best animals have failed to rank as producers expected. That prompted animal science professor Larry Schaeffer and postdoctoral students Janusz Jamrozik and Fernando Grignola to create computerized statistical models to improve genetic evaluation methods for production (milk solids, fat and protein content) traits.
Central to the models is a new procedure called the test day method, developed by Jamrozik. It improves the accuracy of predictions, especially when lactation records are incomplete.
"Increasing the evaluation frequency will benefit producers," says Schaeffer. "By adopting the test day method, they'll experience fewer fluctuations in the evaluations of their herds over time."
The test day method is a monthly recording system for milk. About 10 test day records are collected during the 305 days a cow milks. An overall average is then calculated to complete the record. This provides better accuracy than the previous total milk recording systems, which weren't done as often. Canada has recently increased the number of test day evaluations conducted from biannually to quarterly.
Some dairy producers have on-farm computers recording the weight of milk produced daily. Increasing the involvement and participation of these farmers will improve progeny testing records by filling gaps in the data. Schaeffer says this benefits all dairy farmers because comprehensive records allow scientists to predict how productive the daughters of sires will be.
Since 1988, 10 million test day data records have been collected. One million more are collected each year. As the data banks grow and the numbers are crunched, producers gain from better progeny predictions -- a goal all dairy genetics scientists strive to achieve.
The Canadian Dairy Network (CDN) in Guelph is responsible for all genetic evaluation in Canada. Currently, 60 per cent of Canadian dairy cows are sampled.
Schaeffer says farmers co-operate willingly to help the industry.
"The economic impact of genetic evaluations of dairy herds is enormous," he says. "A Producers could stand to gain or lose up to $25,000, depending on where their top bulls rank against other Canadian Holsteins."
As international markets for dairy continue to open up, it has become even more important to predict how sires will do. And that's what Schaeffer's work allows.
"The new models will help provide dairy producers with better tools for selecting genetically superior animals that are profitable," he says.
Support for this research is provided by the Canadian Breeding Research Council and the Natural Sciences and Engineering Research Council.
