Influence of an experimental infection of nodular worms (Oesophagostomum spp.) on performance of pigs.

Four trials were conducted to determine the effect of different levels of nodular worm (Oesophagostomum spp.) infection on the performance of growing-finishing swine and on digestion and absorption of nutrients by the growing pig. In each of two growing-finishing trials, 48 crossbred pigs (average body weight 26.6 kg in trial 1 and 24.4 kg in trial 2) were individually housed and given a single infection of nodular worms (0, 550, 1,100 or 1,650 infective larvae/kg body weight in trial 1 and 0, 1,500, 3,000 or 4,500 infective larvae/kg body weight in trial 2). At 21 days postinfection, pigs given either 1,100 or 1,650 nodular worm larvae/kg body weight required more feed (P less than .05) per unit gain than pigs not infected, but for the 77-day test period, as a whole, nodular worms did not significantly affect performance. in trial 2, pigs given either 3,000 or 4,500 nodular worm larvae/kg body weight were lighter (P less than .05) and gained weight slower (P less than .05) for the first 21 days postinfection than pigs not infected, while pigs given 4,500 larvae gained slower (P less than .05) than pigs on the other three treatments. During the first 21 days after infection, pigs given 4,500 larvae/kg body weight consumed less feed (P less than .05 than pigs given either 0 or 1,500 larvae. Even at the higher levels of infection, nodular worms did not significantly affect performance over the entire 77-day test period. In each of the two other trials, eight crossbred barrows (average body weight 28.8 kg in trial 1 and 28.4 kg body weight in trials 2) were examined for the effects of two levels of nodular worm infection (0 and 4,950 larvae/kg body weight) on digestion and absorption of nutrients and on N balance. Pigs experimentally infected had a lower digestion coefficient for dry matter (P less than .01), ash (P less than .05), crude fiber (P less than .01), N free extract (P less than .05) and N (P less than .05) than noninfected pigs. Pigs not infected with nodular worms had a higher (P less than .05) N balance.