THE GENETIC FOUNDATION OF FITNESS AND REPRODUCTION TRAITS IN AUSTRALIAN PIG-POPULATIONS .2. RELATIONSHIPS BETWEEN WEANING TO CONCEPTION INTERVAL, FARROWING INTERVAL, STAYABILITY, AND OTHER COMMON REPRODUCTION AND PRODUCTION TRAITS

Data sets from 2 large Australian piggeries were used to estimate gene tic parameters for the traits weaning to conception interval (WCIi-1,i ) and farrowing interval (FIi-1,i), number born alive (NBA(i)), averag e piglet birthweight (BWi), 21-day litter weight (W21(i)), and sow sta yability (STAY(1i)) recorded for each ith parity, as well as sow avera ge daily gain (ADG) and backfat (BF) recorded at the end of performanc e test. Over parities and herds, heritabilities for each trait were in the ranges: WCI/FI, 0.0-0.10; NBA, 0.09-0.16; BW, 0.11-0.35; W21, 0.1 2-0.23; STAY(1i), 0.02-0.09; ADG, 0.35-0.37; BF, 0.36-0.45. Genetic co rrelations between NBA(1) and NEA from later parities were significant ly different from 1. In addition, in 1 herd negative genetic correlati ons (r(g) = -0.04 to -0.25) were found between sow stayability traits and NBA(1), but not NEA recorded in later parities. Stayability was un favourably correlated with ADG and BF, and favourably correlated with WCI12 However, WCI12 was unfavourably correlated genetically with BF ( r(g) = -0.24) but uncorrelated with ADG. Antagonistic relationships al so existed between NEA and BW, NEA and W21, and BW and STAY. In additi on to the traditional traits currently included in pig-breeding progra ms (e.g. ADG, BF, and NEA), traits such as WCI, BW, and STAY should al so be considered as selection criteria to minimise the detrimental eff ects of antagonistic genetic relationships between traits.