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Conformation traits of Holstein cows and their association with the Pro$ selection index.

L. Alcantara




Conformation traits of Holstein cows and their association with the Pro$ selection index.
L. Alcantara*1, C. Baes1,2, G. Oliveira Junior1, F. Schenkel1. 1Centre for Genetic Improvement of Livestock, University of Guelph Guelph, ON, Canada, 2Institute of Genetics, Vetsuisse Faculty, University of Bern Bern, Switzerland.

Breeding programs across the globe are shifting their selection goals from production-driven to more balanced indexes that include traits of direct and indirect economic significance, such as conformation, fertility and health. In Canada, for instance, changes were made to better reflect producers and market needs in the wake of improved accuracy of genetic and genomic evaluations and national efforts regarding data recordings. In 2015 a new national profit index, Pro$, was introduced to maximize production yields, while maintaining functional and conformation traits, taking into consideration the accumulated profit to 6 years of age of proven sire's daughters. The Canadian classification system comprises several linear and nonlinear descriptive traits and defective characteristics that are taken into account to calculate points, which are distributed in 4 different scorecard sections: Mammary System (MS), Feet & Legs, Dairy Strength (DS) and Rump. Understanding the contribution of each of these traits to a monetary index, such as Pro$, would help producers make culling and mating decisions ultimately resulting in more profitable herds. Therefore, the present study used statistical regression and principal component analysis to look at the overall and individual contribution of 23 classification traits to the Pro$ index using deregressed Estimated Breeding Values from 9,292 proven bulls (Lactanet). The total variance explained by the full model was 0.66, and out of the traits included in the model, Dairy Capacity contributed the most to the increase in Pro$. Stepwise backward regression analysis indicated that all traits should remain in the full model. Principal component analysis showed that the vast majority of traits contributed positively to Pro$ values. Traits from the MS contributed the most to the increase in Pro$ values, whereas Thurl Placement and Rump Angle did not seem to have a sizeable impact on Pro$.

Keywords: conformation traits, Pro$, Holstein.

Biography: During his undergraduate studies in Biotechnology, Lucas acquired experience in genetic polymorphisms, molecular biology, and in the production and purification of industrial enzymes. During his master's in Biosciences he decided to understand the role of different bacteria from the rumen in the degradation of plant cell wall through bioinformatics analyses and to target species with the potential for industrial enzymes production. His passion for research and new challenges led him to pursue a Ph.D. in Animal Science, where he seeks to understand the impact of cutting-edge technologies on breeding strategies for optimum sustainable genetic progress in Canadian dairy cattle.