29 Late-Breaking: Genetic and phenotypic analysis of testis size in boars and reproductive traits in sows. (7th December 2018) - Pereira Sanglard, L
Abstract: The female reproductive ability is crucial to the efficiency of swine production, but genetic progress is limited by its low heritability and sex-limited expression. Thus, the objective of this study was to understand the relationship between testis size in boars and reproductive traits in sows. In this study, Yorkshire and Landrace boars (161) and sows (420) were analyzed for testis (boars) width (TW) and area (TA) and reproductive traits (sows): total born (TB), number born alive (NBA), alive 48h (alive48), total born dead (TBD), stillborn, and mummies. Genetic analyses were performed including the fixed effects of age, breed, contemporary group, and parity (for sow traits only), and a random animal effect in the models. The 420 sows were daughters of 13 of the 161 boars. For the phenotypic analysis, we performed a Poisson regression of the reproductive traits of the 420 daughters on the testis size of their 13 sires, with parity and breed of the sow as fixed effect and sow as random effect, and TW or TA as fixed covariates (linear and quadratic). The heritability estimates of TA and TW were 0.69 ± 0.22 and 0.66 ± 0.21, respectively, and the reproductive traits ranged from 0.01 ± 0.01 (TBD) to 0.09 ± 0.04 (NBA). The phenotypic analysis showed quadratic (P < 0.05) and linear (P < 0.05) relationships between reproductive traits in sows with TA and TW, respectively. The optimum TA ranged from 17.09cm2 to 18.55cm2 associated with higher number of TB, NBA, and alive48 (P < 0.05), which did not overlap with the range related to higher number of TBD, mummies, and stillborn (16.0cm2 to 16.57cm2; P < 0.05). Also, increasing the testis width is associated with an increase in TB, NBA, and alive48 (P < 0.05) but not TBD, mummies, and stillborn (P>0.05). Phenotypic assessment of testis size of sires may be a useful tool to select/cull animals for breeding, improving female performance.