Estimating genetic and phenotypic parameters of cellular immune-associated traits in dairy cows

Publication date: April 2017
Source:Journal of Dairy Science, Volume 100, Issue 4
Author(s): Scott J. Denholm, Tom N. McNeilly, Georgios Banos, Mike P. Coffey, George C. Russell, Ainsley Bagnall, Mairi C. Mitchell, Eileen Wall
Data collected from an experimental Holstein-Friesian research herd were used to determine genetic and phenotypic parameters of innate and adaptive cellular immune-associated traits. Relationships between immune-associated traits and production, health, and fertility traits were also investigated. Repeated blood leukocyte records were analyzed in 546 cows for 9 cellular immune-associated traits, including percent T cell subsets, B cells, NK cells, and granulocytes. Variance components were estimated by univariate analysis. Heritability estimates were obtained for all 9 traits, the highest of which were observed in the T cell subsets percent CD4⁺, percent CD8⁺, CD4⁺:CD8⁺ ratio, and percent NKp46⁺ cells (0.46, 0.41, 0.43 and 0.42, respectively), with between-individual variation accounting for 59 to 81% of total phenotypic variance. Associations between immune-associated traits and production, health, and fertility traits were investigated with bivariate analyses. Strong genetic correlations were observed between percent NKp46⁺ and stillbirth rate (0.61), and lameness episodes and percent CD8⁺ (−0.51). Regarding production traits, the strongest relationships were between CD4⁺:CD8⁺ ratio and weight phenotypes (−0.52 for live weight; −0.51 for empty body weight). Associations between feed conversion traits and immune-associated traits were also observed. Our results provide evidence that cellular immune-associated traits are heritable and repeatable, and the noticeable variation between animals would permit selection for altered trait values, particularly in the case of the T cell subsets. The associations we observed between immune-associated, health, fertility, and production traits suggest that genetic selection for cellular immune-associated traits could provide a useful tool in improving animal health, fitness, and fertility.



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