The effect of selected factors on litter and piglet weight at the age of 21 days

In a pedigree farm of 240 Polish Large White sows litter and piglet weights were assessed in relation to major traits of sows. A total of 2131 litters from the years 1994-1999 were analysed coming from 465 sows. Piglet weight increased along with the increase in daily live weight gain and meat content of carcass of gilts (P<0.05 and P<0.01). However, differences in litter weight were not found significant. The highest litter weight was affected by the number of piglets in the litter (13 and more), but piglets from that group of sows were the lightest (P<0.01). The highest mean live body weight was found in piglets coming from smaller litters (10 piglets and less). A higher litter weight was also the effect of the number of litters born by a sow during its productive life (P<0.01 and 0.05) especially when they were litters of sows giving 4-7 litters during their productive life. Successive years caused an increase in the fertility of sows and in litter weight, but also a decrease in mean piglet weight (P<0.01). Starting from the 7th cycle the uniformity of weight of piglets and of litters was deteriorating. The highest uniformity in litter and piglet weights was found when sows exhibited average weight gain and average meat content of carcass at the age of 180 days, had their first litter at the age of 331-380 days, as well when the litter contained 11-12 piglets or when the piglet and litter originated from sows estimated as of medium fertility (11-12 piglets).