PSI-6 Genetic Parameters for Food Allergy Responses in Divergently-selected Pig Lines

Abstract Genetic selection for health and welfare-related traits is paramount in livestock breeding. Piglet allergic responses to soybean protein negatively impact animal growth and welfare. The objectives of this study were to estimate the heritability of soybean allergic responses and genetic correlations between soybean and peanut allergies (r1,2) in divergently-selected pig lines. The base population consisted of nine sire lines (primarily Yorkshire and Landrace) and two dam sources (Yorkshire × Chester White-F1 and Landrace × Yorkshire-F1). Soybean and peanut-allergic responses were measured through a skin test (0–6 scale; 0-no allergic responses; 6-severe allergic responses; characterized by wheal and flair) on pigs fed a diet containing soybean meal for 21 d post-weaning. A total of 5,505 animals from nine generations of two contrasting lines (i.e., high and low skin test reaction) were included in the analyses. The statistical model included contemporary group, breeding lines, replication, sex, and weaning weight (linear covariate) as fixed effects (P-value < 0.05), and additive genetic, maternal genetic, and maternal permanent environment as random effects. Threshold and linear Bayesian models were used to estimate genetic parameters, using a pedigree-based relationship matrix containing 9,201 animals. The heritability estimates for the general soybean allergic response were 0.199 ± 0.045 and 0.119 ± 0.025 for the threshold (liability scale) and linear models, respectively, suggesting that soybean allergic responses are heritable and can be improved through selective breeding. A weak negative genetic correlation between allergic responses and birth weight was observed (r1,2 = -0.253 ± 0.192), which shows that the genetic variance of soybean allergy is less dependent on birth weight. However, a high positive genetic correlation was estimated between soybean and peanut-allergic responses (r1,2 = 0.89 ± 0.048), which indicates a potential cross-reactivity of soybean and peanut allergies. Our findings suggest that it is possible to reduce food allergy responses in pigs through selective breeding.