GENETIC-PARAMETERS FOR GROWTH TRAITS IN PIGS ESTIMATED USING 3RD-DEGREE POLYNOMIAL FUNCTIONS

A total of 8745 purebred Yorkshire and Landrace pigs extracted from Fi nnish progeny test station data was analysed. The pigs were weighed we ekly during the test. A third degree polynomial function, age = f(weig ht), was fitted separately for each pig and was used to describe the g rowth patterns of individual pigs. Their live weight at the inflection point (LWip) was 72 kg, age at the inflection point (AGE(ip)) 126 d, and maximum daily gain (DG(max)) 1111 g/d, on average. The average dai ly gain from 30 to 90 kg (ADG(30-90)) was 957 g/d and in the smaller w eight ranges (30 to 50, 50 to 70 and 70 to 90 kg) the average daily ga ins were 829, 1042 and 1046 g/d, respectively. Genetic parameters for growth and carcass traits were estimated using REML with an animal mod el. The heritability estimates (h(2)) for LWip, AGE(ip) and ADG(30-90) were 0.08, 0.33 and 0.23, respectively, and for smaller weight ranges from 0.14 to 0.21. Fast growing and lean animals had higher LWip than others and the r(g) between LWip and ADG(30-90), DG(max) and M% was 0 .58, 0.73 and 0.57, respectively. The r(g) between ADG(30-90) and M% w as close to zero.