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397
Genetic correlations between predicted milk fatty acids and milk production traits in Canadian Holsteins

Wednesday, July 20, 2016: 4:00 PM
Grand Ballroom I (Salt Palace Convention Center)
Allison Fleming , Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
Flavio S Schenkel , Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
Astrid Koeck , Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
Francesca Malchiodi , Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
Ayesha Ali , Dept of Mathematics and Statistics, University of Guelph, Guelph, ON, Canada
Bonnie Mallard , Dept of Pathobiology, OVC, University of Guelph, Guelph, ON, Canada
Milena Corredig , University of Guelph, Guelph, ON, Canada
Filippo Miglior , Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
Audio File Recorded Presentation (mp4)
Abstract Text:

The fatty acid profile of milk is of importance due to its implications on human health and nutrition, and technological attributes. Any consideration of selection for fatty acids requires knowledge of their genetic relationship with other milk production traits. The objective of this study was to investigate the genetic correlations between mid-infrared predicted milk fatty acids and recorded production traits and somatic cell score (SCS) in Canadian Holsteins. Test-day records for milk yield, fat and protein percentage, fat:protein ratio, and SCS, along with predicted quantities of short (4 to 10 carbon length), medium (12 to 16 carbon length), and long-chain (17 to 22 carbon length) fatty acid groups were analyzed. First lactation Holstein cows between the ages of 19 and 43 months with at least 3 test-day fatty acid records were considered in the analysis. A total of 109,249 records from 29,542 Holstein cows and 2,198 herds acquired between January 2013 and April 2015 were used. Genetic analysis was performed using bivariate sire random regression models fitted using the Average Information-Restricted Maximum Likelihood (AI-REML) procedure in the DMU package with Legendre polynomials used to describe the regression curves. Daily genetic correlations were averaged across the lactation. Strong genetic correlations of 0.90, 0.96, and 0.88 were found between fat percentage and short, medium, and long-chain fatty acids, respectively. Ranges of genetic correlations for fatty acid groups and milk yield (-0.48 to -0.50), protein percentage (0.69 to 0.80), and fat protein ratio (0.51 to 0.63) were similar to those found between the production traits and milk fat percentage. Weak, negative genetic correlations were observed between SCS and short and medium-chain fatty acids (-0.14 for both), while a weak, positive correlation was found between SCS and long-chain fatty acids (0.17). Milk fatty acids had moderate to strong genetic correlations with production traits, but weak genetic correlation with SCS. However, disentangling the high correlation of fatty acids with fat percentage may be challenging for selection purposes.

Keywords: fatty acid, milk production, genetic correlation

See more of: Breeding and genetics: Selection for improved efficiency
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