title: Genetic analysis of superovulatory response of Holstein cows in Canada.
abstract: Superovulation of dairy cattle is frequently used in Canada. The cost of this protocol is high, and so is the variability of the outcome. Knowing the superovulatory potential of a donor cow could influence the breeder's decision to superovulate it or not. The main objective of this study was to perform a genetic analysis for superovulatory response of Holstein cows in Canada using data recorded by Holstein Canada, and to investigate if these data could be used for genetic evaluation. Data contained the total number of embryos and the number of viable embryos from every successful flushing performed across Canada. After editing, 137,446 records of superovulation performed between 1992 and 2014 were analyzed. A univariate repeatability animal model analysis was performed for both total number of embryos and number of viable embryos. Because both data and residuals did not follow a normal distribution, records were subject to either logarithmic or Anscombe transformation. Using logarithmic transformation, heritability estimates (SE) of 0.15 (0.01) and 0.14 (0.01) were found for total number of embryos and number of viable embryos, respectively. Using Anscombe transformation, heritability estimates (SE) of 0.17 (0.01) and 0.14 (0.01) were found for total number of embryos and number of viable embryos, respectively. The genetic correlation between the 2 traits was estimated at 0.97 using logarithmic transformation and 0.95 using Anscombe transformation. Breeding values were estimated for 54,463 cows, and 3,513 sires. Only estimated breeding values of sires having a reliability higher than 40% were considered for estimated breeding values correlations with other routinely evaluated traits. The results showed that selection for a higher response to superovulation would lead to a slight decrease in milk production, but an improvement for functional traits, including all reproduction traits. In all cases, the estimated correlations are either low or modest. We conclude that genetic selection for increased superovulatory response in donors is possible; daughters of sires with high estimated breeding values for superovulatory response will tend to yield more embryos, whereas the additive effect of service sire seems not to contribute to the variability of the 2 superovulation traits and was not significantly correlated with the additive effect of the donor.
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1; Centre d'insémination artificielle du Québec (Ciaq), Saint-Hyacinthe, Québec, Canada, J2S 7B8. Electronic address: cjaton@uoguelph.ca.
authors.forename: C
authors.initials: C
authors.lastname: Jaton
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: A
authors.initials: A
authors.lastname: Koeck
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1; Semex Alliance, Guelph, Ontario, Canada, N1G 3Z2.
authors.forename: M
authors.initials: M
authors.lastname: Sargolzaei
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: F
authors.initials: F
authors.lastname: Malchiodi
authors.affiliation: Université de Montréal, Faculté de médecine vétérinaire, St-Hyacinthe, Québec, Canada, J2S 2M2.
authors.forename: C A
authors.initials: CA
authors.lastname: Price
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1.
authors.forename: F S
authors.initials: FS
authors.lastname: Schenkel
authors.affiliation: Centre for Genetic Improvement of Livestock (CGIL), University of Guelph, Guelph, Ontario, Canada, N1G 2W1; Canadian Dairy Network (CDN), Guelph, Ontario, Canada, N1K 1E5.
authors.forename: F
authors.initials: F
authors.lastname: Miglior
mesh_terms: D000818:Animals; D001947:Breeding; D002417:Cattle; D005260:Female; D005820:Genetic Testing; D007774:Lactation / Q000235:genetics; D010641:Phenotype; D015203:Reproducibility of Results; D013480:Superovulation
keywords: Holstein; breeding value; embryo production; genetic parameter; superovulation