Abstract:
An analysis of data, recorded during 1993 2001, on the performance test and reproductive traits of 2,038 sows (Large White=739, Landrace=710, Duroc=317 and Yorkshire=272) of a commercial pig farm was conducted using multivariate animal model by Restricted Maximum Likelihood (REML). The estimated heritability values ranged from 0.48 to 0.5138 for backfat thickness (BF), from 0.1119 to 0.1474 for total number of pigs born (TB) and from 0.0864 to 0.1396 for number of pigs born alive (BA). The genetic and phynotypic correlations between BF and TB ranged from -0.0515 to 0.1411 and from 0.0117 to 0.1237 respectively. The genetic and phynotypic correlations between BF and BA ranged from -0.0516 to 0.1541 and from 0.0111 to 0.1250 respectively. Selection for decreased backfat thickness had direct selection response ranging from 0.0001+-0.0001 to 0.0042+-0.0019 mm./year. The correlated responses in the first parity for TB[subscript 1] and BA[subscript 1] were 0.0059+-0.0004 and 0.0055+-0.0005 pigs/yr, respectively. Records from sows fulfiling in the first three parities showed the correlated responses for TB[subscript 1-3] and BA[subscript 1-3] as 0.0053+-0.014 and 0.0020+-0.0011 pigs/yr, respectively. In the first five parities, The correlated responses for TB[subscript 1-5] and BA[subscript 1-5] in sows that completed were 0.0027+-0.0005 and 0.0001+-0.0004 pigs/yr, respectively. These results indicated that reducing BF did not affect the first parity performance in any breeds but could result in a decrease in BA[subscript 1-3] of Yorkshire and BA[subscript 1-5] of Large White and Landrace.