Genetic parameters for lean meat yield, meat quality, reproduction and feed efficiency traits for Australian pigs

Abstract

Data from 3350 Large White and Landrace boars, recorded between July 1992 and June 1995, was used to estimate genetic parameters for performance, carcase and meat quality traits. Manufacturing traits were available on a subset of approximately 1000 animals. This data set was linked with data from 6050 Large White and Landrace sows that farrowed from January 1990 to March 1995. In total, 36 traits were analysed including average daily gain from three to 18 weeks (ADG1) and from 18 to 22 weeks (ADG2), life time average daily gain (ADG3), feed intake (FDINT), feed conversion ratio (FCR) and lean meat growth (LEANG). Heritability estimates for these traits were 0.27, 0.13, 0.27, 0.23, 0.15 and 0.28, respectively. Carcase traits included real time ultra sound and Hennesy Chong measurements. Heritability estimates for backfat measurements and lean meat percentage ranged from 0.44 to 0.63 while from the two muscle depth measurements only muscle depth recorded with real time ultra sound was heritable (0.21). Further carcase traits analysed were the weight of the whole back leg (BLW, h2 =0.22) and the slash boned ham (LMW, h2 = 0.38). Meat quality traits included pH45 and pH24, colour of the 'm. longissimus dorsi' (CLD) and 'm. multifidus dorsi' (CMD), drip loss percentage (DLP) and intramuscular fat content (IMF). Estimates of heritabilities were 0.15, 0.14, 0.29, 0.30, 0.23 and 0.35, respectively. Heritability estimates for ham yield (HAM) and middle yield (MID) were 0.11 and 0.06. Reproductive traits of the sow included litter size (NBA 1.2.3), litter birth weight (LBW 1.2.3) and average piglet weight at birth (ABW 1.2.3) for the first three parities as well as 21 day litter weight for the first parity (LW21 1). Estimates ranged from 0.07 to 0.22. The genetic correlation between ADG1 and ADG2 was 0.32. Differences in age, housing system and gut filling at the beginning and end of testing contributed to this low relationship which might also be the reason for favourable genetic relationships between ADG1 and leanness in contrast to unfavourable genetic correlations between ADG2 and leanness. The favourable relationship between ADG1 and leanness might be due to a lower feed intake capacity in regard to the protein deposition capacity of these young boars. ADG1 is primarily during the protein accretion phase while ADG2 is during the fat accretion phase. Genetic correlations between FDINT and backfat measurements ranged from 0.54 to 0.63 and was negative with LMW (-0.11).