An analysis of variation in performance traits of Large White and Landrace boars tested in the Queensland pig testing station

Abstract

An analysis of variation was made of eight traits measured on 299 Large White and 185 Landrace boars performance tested from 27 to 90 kg liveweight over a three-year period. The traits were feed conversion, daily gain, subcutaneous fat depths at the shoulder, mid-back, C, K and loin positions and a fat score combining all fat depths. Boars were assessed on a breeding index combining food conversion, daily gain and fat score. Apart from daily gain and shoulder fat, there was a significant negative time trend in all traits. Landrace were superior to Large White in all traits except C, K and loin fat for which the breeds were the same. The genetic relationships among tested boars were determined and were used to estimate the contributions of additive genes and herd and litter of birth environments to variation in boar performance. For feed conversion, daily gain and fat score the contributions were from additive genes 12, 0, 29 per cent, from herd environment 14, 17, 12 per cent and from litter environment 23, 43, and 24 per cent respectively. A comparison of the performances of 109 tested sons and their sires gave values of 0.6 and 0.5 for the realised heritabilities of the breeding index for Large White and Landrace.