Best linear unbiased estimates of growth for different environmental factors in Landrace and desi crossbreds

The records on 918 crossbred piglets (50% Landrace + 50% desi), progeny of 39 sires, over a period of 8 years from 1987 to 1994, maintained at the Liv estock Production Research (Pigs) were used in this study to determine the influence of various environmental factors on growth using maximum likeliho od (M L) procedure. Body weight of piglets were recorded at birth and there after at one-week-interval up to weaning (8 week). Growth in different week s was estimated from the recorded weights. The prior heritability estimates used in ML analysis were obtained from the same data. Generation had significant effect on growth from first to fourth week and t hereafter, at seventh week of age. Effect of sex and age at farrowing was n onsignificant at different ages. Season of birth affected growth at first, fourth, fifth and eighth week. Effect of litter size and parity was signifi cant on growth almost up to fifth week. Inbreeding had no effect on growth in most of the weeks. Piglets born in later generations had higher growth. Generation 1 showed lowest growth almost in most of the weeks except in thi rd and sixth week. September, October and November were more favourable con ditions for sows to produce maximum amount of milk and for piglets to achie ve highest growth. Piglets born in smaller litters received better growth i n most of the weeks than those born in larger litters. Growth in second, th ird and fifth week was highest in piglets of third parity sows followed by those of second and first parity. Though effect of inbreeding was nonsignif icant at most of the weeks, however, non-inbreed piglets had higher growth than those of inbreds.