Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: May 30, 2000
Publication Date: June 1, 2000
Citation: Cassady, J.P., Leymaster, K.A. 2000. Effects of recombination on weight from birth to 154 days of age in pigs. [abstract]. Journal of Animal Science. 78(Suppl. 1):69. Technical Abstract: The objective was to determine the influence of nonadditive gene action on pig growth in two experiments. Experiment 1 (Exp1) included Yorkshire, Landrace, Large White, and Chester White pigs. Experiment 2 (Exp2) included Duroc, Hampshire, Pietrain, and Spot pigs. Data were recorded on purebred, two breed, and F1 through F6 generations, where F1 pigs are the first generation of a four-breed cross. Pig weights were recorded at birth, 14, 28, 56, 70, 98, 126, and 154 d of age. Number of observations at birth and 154 d of age were 7,685 and 4,351 in Exp1 and 7,159 and 3,996 in Exp2, respectively. Data from each experiment were analyzed separately. A mixed-model analysis was done with fixed effects of year and sex and random effect of sire within year. Included as covariates in each model were effects of direct and maternal heterosis and an effect due to recombination in crossbred animals, which is the breakdown of epistatic effects present in purebreds. Models also included direct, maternal, and grandmaternal effects of each breed as covariates. Effects of direct heterosis increased (P < .1) weights at all ages in both experiments. In Exp1 effects due to recombination were negative (P < .1) for birth weight and positive (P < .1) for weight at 98 and 126 d of age. In Exp2 effects due to recombination were positive (P < .1) for weights at birth, 14, and 28 d of age. Recombination effects did influence pig weights at early ages in both experiments. Epistasis affects early pig growth and thus, may indirectly affect pig viability. Effects of recombination on birth weight were in opposite directions in the two experiments. Advances in molecular techniques may allow for selection of favorable epistatic effects.