Analysis of some factors influencing the birth weight of piglets

Effects of a hybrid combination, sex, parity and number of all piglets born per litter on the individual birth weight of piglets were studied in a commercial herd of pigs. Experiments were performed using four hybrid combinations: cross-bred sows (Czech Large White x Czech Landrace) were artificially inseminated with sement of boars of the following breeds and hybrid combinations: Czech Large White - sire line, Duroc, (Duroc x Hampshire), (Pietrain x Hampshire). Individual weights of piglets were recorded at birth together with their sex, number of piglets per litter and the rank of parity. Altogether 960 piglets were weighed and their average birth weight was 1258 grams. Results were evaluated using the unifactorial variance analysis. As compared with other three combinations, piglets of the hybrid combination (CLW x CL) x CLW - sire line showed the highest average birth weight (1339 g); this difference was statistically highly significant (P less or equal 0.01). A statistically highly significant difference (P less or equal 0.01) existed also between birth weights of male and females. The effect of parity rank on the birth weight of piglets was also highly significant. A positive trend in birth weights of piglets with the increasing rank of parity. Birth weights increased gradually from the first parity (1247 g), culminated on the 5th parity (1337 g) and thereafter gradually decreased to 1111 g on the 10th parity. When evaluating the effect of the total number of all piglets born per litter on the birth weight it was found out that the heaviest piglets was in a litter with three piglets while the lightest ones were in the most numerous litters with 16 piglets (1169 g). Basing on values calculated for interactions of the 2nd degree of the four-factorial variance analysis it was concluded that the most significant was the interactions between the hybrid combination and the parity, the hybrid combination and the number of all piglets born per litter and between the parity and the number of all piglets born per litter. The correlation existing between the birth weight and the number of all piglets born per litter (r = 0.0004), combinations, sex were low but significant.