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Centre for Genetic
Improvement of Livestock A Mindful Model |
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A new statistical model that predicts daily milk yields could mean greater flexibility for dairy producers involved in milk recording programs, allowing them to decrease their costs while maintaining the accuracy of their records. Prof. Larry Schaeffer and research associate Dr. Janusz Jamrozik, Centre for Genetic Improvement of Livestock, graduate student Renate Van Dorp, Don Lazenby from the Ontario Dairy Herd Improvement Corporation (Ontario DHI) and Prof. David Kelton, Ontario Veterinary College, have developed factors to predict 24-hour milk, fat and protein yields from a single milking - figures known as test day records - for dairy cows that are milked either two or three times daily. Determining Genetic Potential Test day records are used in the new Canadian Test Day Model (CTDM) that was also developed by Schaeffer and Jamrozik. The CTDM accurately determines the genetic potential of dairy cows and their sires for production traits. Test day records are collected monthly for each animal's first three lactations. The results from the CTDM are expressed as estimated breeding values (EBV). For official test day records, EBVs for sires are published as bull proofs or cow indexes by the Canadian Dairy Network so that breeders can assess an animal's genetic performance. Milk Recording is Beneficial Approximately 70 per cent of dairy farms in Ontario are voluntarily involved in milk recording programs. Milk recording is beneficial to producers because each farm receives production information about their dairy cows from Ontario DHI, as well as management information for their herd. But it's still a costly initiative for dairy producers. Although the development of new software and hardware programs has improved milk recording, a visit from an Ontario DHI supervisor can slow down a facility's production on test day. As well, there is a fee for this service. So milk recording organizations are trying to improve the flexibility of data collection by allowing producers to choose how often they want to provide data. "A more flexible milk recording system could make it easier for producers to continue to participate" says Schaeffer. Traditionally, dairy herds are milked twice a day. A growing number of farmers are now milking three times a day - a practice that increases milk production by about 10 per cent. However, many producers have avoided the three-times daily milking scheme there were no accurate factors for estimating daily milk yields from just one or two milkings (instead of all three) using this scheme, so highly coveted official genetic evaluations could not be provided for their cows. Lazenby and Kelton initiated the research by collecting data from farms that were milking three times daily. The new factors are aimed to help producers get the information they need by generating accurate test day records for genetic evaluation. The most ideal and accurate milk recording schedule would involve taking weights and samples at all milkings. But farmers prefer not to have the Ontario DHI supervisor on the farm all day. With this model, yields from a particular milking can be used to extrapolate the yields for 24 hours. For example, data can be collected at the morning milking only, or the morning and afternoon. Even without data from each milking, daily yields can be estimated and included in the test day model, giving the farmers more flexibility in choosing the appropriate milk recording alternative for them. This research was sponsored by the Ontario Ministry of Agriculture, Food and Rural Affairs. |
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