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.

Endogenous development of the swine coccidium, Isospora suis Biester 1934.

The endogenous development of Isospora suis Biester 1934 is described in piglets inoculated with 150,000 or 200,000 sporulated oocysts. Endogenous stages developed within villous epithelial cells throughout the small intestine. Two distinct types of meronts were seen in tissue sections. Type I meronts, which were seen at 3 days postinoculation, were binucleate, elongate, and 10.5 by 4.7 micron. They produced two to 14 Type I merozoites per parasitophorous vacuole. Type I merozoites were 10.0 by 3.6 micron. They produced two to 14 Type I merozoites per parasitophorous vacuole. Type I merozoites were 10.0 by 3.6 micron. Type II meronts, which were seen at 4 days postinoculation, were elongate and contained three to 12 nuclei. Type II meronts were 11.4 by 5.3 micron, and one to four were found per parasitophorous vacuole. Type II merozoites were 6.3 by 2.1 micron, and three to 16 were found per parasitophorous vacuole. The peak of asexual development occurred 4 days postinoculation. Fully developed microgamonts, macrogamonts, and oocysts were seen 5 days postinoculation. The prepatent period was 5 days, and the patent period was 5 to 8 days. No extraintestinal stages were seen.

Ultrastructure of macrogametogenesis of Eimeria mivati.

The development of the macrogamete of Eimeria mivati Edgar and Seibold 1964 was studied with the electron microscope. Development of the young gamont was characterized by a loss of organelles such as the apical complex, subpellicular microtubules, rhoptries and micronemes, followed by an increase in micropores, mitochondria, rough endoplasmic reticulum (rER), and Golgi complexes. Nuclear detachment bodies and canaliculi were present in maturing macrogamonts. Amylopectin was first observed as small electron-dense rod-like bodies that eventually became large electron-transparent bodies. Type II wall-forming bodies developed in the cisternae of the rER. Type I wall-forming bodies appeared shortly thereafter in close association with numerous Golgi complexes. Many small vesicles located between the cisternae of the rER and the Golgi complexes formed what appeared to be a secretory pathway whereby protein formed in the cisternae and, modified by the Golgi complex, may produce the type I wall body material. The outer wall of the oocyst developed between two distal membranes on the surface of the macrogamete. Although the actual mechanism of deposition of the wall material was not seen, it was probably by some secretory process. Wall-forming bodies did not fuse.

Eimeria Macyi sp. n. (Protozoa: Eimeriidae) from the eastern pipistrelle, Pipistrellus subflavus, from Alabama.

The subspherical to broadly ellipsoidal oocysts of Eimeria macyi measure 16 to 21 by 15 to 19 mu (mean 19.0 by 17.6 mu), and sporocysts measure 10 to 12 by 6 to 8 mu (mean 11.0 by 7.0 mu). The rough walled oocysts lack a micropyle and residuum, but a sporocyst residuum and polar granule are present. This is the first description of coccidian oocysts from the genus Pipistrellus.