A genetic study of reproductive and productive traits of Landrace sows in Thailand

Data from Thai Landrace sows were used to estimate genetic parameters for reproductive and productive traits in the first and later parities, Reproductive traits investigated were total number of piglets born per litter (TB), stillborn (SB) and number of piglets born alive but dead (BAD) within 24 hours. Reproductive data contained 12,600 litters born between 1993 and 2005. Performance data were average daily gain (ADG) and backfat thickness (BF) from 15,171 gilts. Analyses were carried out with a multivariate animal model Using average information restricted maximum likelihood procedures. Heritability estimates of reproductive traits for first parity were as follow: 0.03 (TB), 0.04 (SB) and 0.06 (BAD); and for later parities: 0.07 (TB), 0.03 (SB) and 0.02 (BAD). Heritability estimates for performance traits were 0.38 (ADG) and 0.61 (BF). A favorable genetic correlation was estimated between ADG and TB (r(g) = 0.22). Back fat was unfavorably genetically correlated to SB (r(g) = -0.22), land the genetic correlation between TB and BAD was also unfavorable (r(g) = 0.40). Genetic correlations of TB, SB and BAD between first and later parities were 0.85, 0.79 and 0.76 respectively. It is concluded that selection for high growth rate will increase TB and selection for low BF will increase SB. The results showed further that BAD will increase if the selection pressure is for high TB.