Growth hormone gene polymorphisms and growth performance traits in Duroc, Landrace and Tao-Yuan pigs

This study investigated the restriction fragment length polymorphism (RFLP) of the porcine growth hormone (pGH) gene in Duroc, Landrace, and Tao-Yuan pigs and its effects on growth performance and levels of plasma growth horm one in peripheral circulation. Genomic DNA extracted from 81 Tao-Yuan, 60 L andrace and 48 Duroc pigs were subjected to Southern blot hybridization wit h a pGH cDNA probe. Polymorphism was detected with the restriction enzymes TaqI and DraI. A comparison of these three breeds showed significant differ ences in allelic frequencies. Blood samples for radioimmunoassay (RIA) of G H were collected biweekly during the experimental period from pigs 12 to 40 weeks of age. Tao-Yuan pigs showed a mean plasma GH level (2.51 +/- 1.23 n g/mL) that was much lower than that of the Landrace (3.80 +/- 1.52 ng/mL) a nd Duroc (4.20 +/- 1.03 ng/mL.) pigs (P< 0.05). Moreover, the Tao-Yuan pigs also showed poorer growth performance than the Landrace and the Duroc pigs both in the daily weight gain (0.37 +/- 0.06 vs. 0.67 +/- 0.05 and 0.70 +/ - 0.05 kg/day, P< 0.01) and feed efficiency (3.12 +/- 0.28 vs. 2.60 +/- 0.1 4 and 2.52 +/- 0.12, P< 0.05). These results suggest that the growth perfor mance trait in these pigs is highly correlated with their growth hormone ge notype. (C) 2000 by Elsevier Science Inc.