Correlation between an oestrogen receptor gene and reproductive traits in purebred and crossbred pig populations

The relationship between an oestrogen receptor (ESR) gene and reproductive traits in 11 Large White (LW), 19 Landrace (L), 22 Meishan (MS), 22 Meishan × Large White (MS × LW) F 1 , 26 Large White × Meishan (LW × MS) F 1 , 16 Landrace × Large White (L × LW) F 1 and nine Large White × Landrace (LW × L) F 1 female populations was studied. Reproductive characteristics and some performance data were analyzed for associations with ESR genotype, parity and breed. The ESR genotype was associated with length of oviduct (LO). Uterine weight (UW), LO and the weight of two ovaries (OW) of purebred Meishan and LW × MS females were higher than those of purebred Large White and MS × LW females. In Large White and Meishan crosses, crossbreds with Meishan dams had higher UW, LO, uterine horn length (LUH) and OW than pigs with Large White dams. Significant effects of paternal breed of sire were observed for LO and OW. In Large White and Landrace combinations, differences in values between purebred and crossbred animals were found for UW and LO. However, maternal breed effects were not detected for UW, LO, LUH, OW. A significant effect of paternal breed of sire was observed for LO. Females with Landrace sires had a larger LO than females with Large White sires. Keywords : Pig, ESR locus, female reproductive tract components, breed effects South African Journal of Animal Science Vol. 36 (4) 2006: pp. 243-247