Preliminary Results in Dairy Research Cluster 2 – Update on Dairy Cattle Genetics and Genomics

Preliminary Results in Dairy Research Cluster 2 – Update on Dairy Cattle Genetics and Genomics

Dr. Filippo Miglior is Chief of Research & Strategic Development at Canadian Dairy Network (CDN), Adjunct Professor at the University of Guelph and principal investigator of two genetics projects under the Dairy Research Cluster (Hoof Health and Nutraceutical Value of Milk, see www.dairyresearch.ca for short summaries of the work). 

Dr. Miglior has delivered initial results from both projects, which are summarized below. 

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Hoof Health 

Preliminary findings suggest there is sufficient genetic variation to allow for the genetic improvement of hoof health through direct selection. Standardized data collected by hoof trimmers can be used for genetic analysis.  

Initial work by Dr. Nuria Chapinal (Post-Doctoral at U. of British Columbia) found that digital dermatitis was the most frequent hoof lesion (present in 20% of the records) and primarily affected cows in their first lactation. Sole ulcers were the second most common lesion (8% of the records) and their frequency increased as cows aged. The heritability estimates for digital dermatitis and sole ulcer were 8% and 2%, respectively.

Additionally, a funding proposal by the Field Project Manager (Ms. Anne-Marie Christen) was prepared for the implementation of the hoof health data collection in Quebec. Ms. Christen has also prepared an inventory of past and current projects on hoof health across Canada and created a new networking group of professionals, researchers, hoof trimmers and veterinarians.

Nutraceutical Value of Milk

Initial results indicate that selection for milk fat globule and casein micelle size may be possible. The sizes of fat globules and casein micelles in milk have been associated with differences in the technological properties and composition of milk with a possible effect on human health. By decreasing the dimensions of the fat globules and by increasing the content of the milk membrane, milk production could be adapted to specific consumer targets and to the improvement of milk nutraceutical properties. 

A total of 1,330 milk samples from 249 dairy cows in 25 herds were analyzed by Dr. Milena Corredig’s lab (Professor, U. of Guelph). Ms. Allison Fleming (Ph.D. student, U. of Guelph) performed the genetic analysis. High heritabilities of 57% and 50% were found for volume weighted and surface area weighted milk fat globule size, respectively. The heritability of casein micelle size was 29%.

Additional Funding

We are happy to announce that the Ontario Genomics Institute (Toronto, ON) has approved funding to the DairyGen Council of CDN for $25,000 towards genotyping cows to add onto existing funding of the Dairy Research Cluster genetics projects. In order to successfully achieve significant and applicable results, the goal is to genotype at least 10,000 cows with the 50K SNP panel.  By pooling genotypes from various projects and by adding this investment from the Ontario Genomics Institute we expect to lower the cost of genotyping.

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