Meta-analysis for effects of breed and climatic zone in reproduction traits of pig
2017
Arimasu, S. (University of the Ryukyus, Okinawa (Japan)) | Oikawa, T.
Objective of this study was to reveal effects of breed and climatic zone and their interaction for reproduction traits of sows by meta-analysis. A data set included 2097 averages of reproduction traits extracted from 205 published articles. Climatic zone of a test place was classified into temperate, tropical and subarctic zone according to Koeppen's climate classification. Traits in study were 12 traits including total number of piglets born, number of born alive, number of stillborn, number of weaned, age at first farrowing, farrowing rate, average birth weight, average weaning weight, litter weight at birth, litter weight at weaning, farrowing interval and weaning to service interval. Statistics software used for the analysis was MIXED/SAS procedure with a random effect of research article, where residuals were assumed to have heterogeneous variance between known and unknown parity, and the residual variances were weighted by number of records. Test of statistical significance showed that effects of climatic zone, breed, country and parity were significant in most of traits in study, however effect of operation (experiment, breeding vs commercial farms) was significant in a few traits. Global breeds such as Landrace and Large White showed high performance in most of reproductive traits. Their high performance was not restricted only in temperate and subarctic zone, but also in tropical zone compared with other breeds. Results of crossbreds showed their high performance of reproductive traits even at climatic zone out of thermal neutral zone such as subarctic and tropical zone, and their higher reproductive performance was considered to be due to heterosis effect.
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