Influence of thermal stimulation during the late phase of incubation on hatching results and post-hatch broiler performance under commercial conditions.

Two experiments, which differed in breeder age, strain and season, were conducted to study the influence of low-intensity, short-duration thermal stimuli during the late phase of incubation on hatchability and performance. The first experiment conducted in April-June used eggs from Cobb × Ross broiler breeders at 35-41 weeks of age and the second experiment performed in February-April used eggs from Hubbard × Cobb broiler breeders at 49-53 weeks of age. Eggs in the test group had the same physical environment as eggs in the control group except that incubation temperature was increased by 1˚C for 2 h/d above the control group from 18 to 20 d of incubation (DI). The results demonstrated that thermal stimulation of 1˚C for 2 h/d above control incubation temperature during 18-21DI did not have any adverse effects on hatch and post-hatch performance of broilers. In both experiments, treatment did not significantly alter the secondary sex ratio in hatched chickens, but hatch residue showed that the proportion of unhatched male embryos was significantly lower in the test groups than in the control groups. In the first experiment, thermal stimulation improved feed conversion by 1.82% compared with the control.

Extrapulmonary Dirofilaria immitis-like infections in the Western Hemisphere.

One worm recovered from the orbit of a patient in Indiana, and two from the peritoneal cavity of another patient in California are described and classified as Dirofilaria. Both patients were elderly men who have lived all their lives in the United States. The main morphologic feature of these three immature worms is the presence of a smooth cuticle devoid of longitudinal ridges, similar to the cuticle of D. immitis. However, because other dirofilariid with similar cuticular characteristics have been found in animals in the Western Hemisphere, and they cannot be conclusively ruled out as the cause of the infection in our patients, a diagnosis of D. immitis-like organism is proposed for these nematodes. The relationship of these worms to other dirofilariid of animals and humans on the American continent is important because of the diagnostic problems these infections posed to practicing pathologists.

The control and prevention of necrotic enteritis in broilers with zinc bacitracin.

The effectiveness of zinc bacitracin in controlling andpreventing necrotic enteritis was tested by growing broilers in a facility where necrotic enteritis outbreaks had previously occurred. Broiler-crossed chicks were fed a commercial-type broiler diet containing 0 mg./kg., 33 mg./kg., or 55 mg./kg. of zinc bacitracin in the diet. Each treatment was replicated six times. Mortality, weight gain, feed conversion, and pigmentation were measured. The control group had 7.4% mortality due to necrotic enteritis as determined by necropsy of each bird upon death. Zinc bacitracin at 10 grams per ton had two mortalities, or 0.4% mortality due to necrotic enteritis. No mortality due to necrotic enteritis occurred with the higher levels of zinc bacitracin. The addition of zinc bacitracin significantly improved (P less than 0.01) the parameters of weight gain, feed conversion, and pigmentation.