Biomedical subjects

N B Anthony

Publications and source records attributed to N B Anthony.

58 records · Page 4Linked to original sources

PubMedDate not supplied

Genetic variation in resistance of turkeys to experimental challenge with Pasteurella multocida.

Six hundred fifty-five male and female turkeys representing four genetic lines were challenged in 10 experiments over a 3-year period with a field isolate of Pasteurella multocida. Poults were challenged at 45 days of age with 1 ml of an inoculum containing 1.2 x 10(7) bacteria per ml. The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. The number of days from exposure to severe clinical signs or death for Line F (5.8 days) differed significantly from that of Line E (8.2 days), Line RBC1 (8.0 days), and Line RBC2 (8.2 days). There were no significant differences due to sex of poult for number of days from exposure to severe clinical signs or death. Overall mortality observed was 51.2%. Mortality was highest for Line F (72.1%) and differed significantly from that of the other lines. Mortality among male poults did not differ significantly from mortality among female poults.

Animals↗

PubMedDate not supplied

Responses of chickens to Streptococcus faecalis: genotype-housing interactions.

Hens from lines selected for high and low juvenile body weight were maintained in single-bird wire cages or in litter-floor flocks and inoculated intravenously with Streptococcus faecalis. Responses to the inoculation, as measured by changes in body weight, plasma xanthophyll levels, heterophil/lymphocyte ratios, and mortality, were more severe in the high-body-weight line than the low-body-weight line. The effect of cage vs. floor housing varied according to genetic line. Responses of individuals to Str. faecalis could not be predicted from either plasma xanthophyll levels or numbers of heterophils and lymphocytes before inoculation. Diagnosis of field outbreaks would be difficult, because autopsies performed 14 days after inoculation revealed no lesions, and liver swabs positive for Str. faecalis were rare.

Animals↗

PubMedDate not supplied

The leukocyte response of Japanese quail to Rous sarcoma virus-induced tumors.

In male Japanese quail, different circulating leukocyte responses were observed for progressors (birds developing a massive tumor that persisted throughout the experiment) and regressors (birds developing a tumor that gradually disappeared) after initial challenge with Rous sarcoma virus (RSV). Blood was sampled before and at weekly intervals postinoculation. Blood smears were prepared and stained with Diff Quik, and a light microscope (1000 x) was used in a direct count of 50 fields. Leukocytes were classified as heterophils, lymphocytes, monocytes, or eosinophils. The significant increase (P < 0.05) in total leukocytes at 14 days in regressors and progressors was consistent with the increase in tumor growth. The regressors' individual percentage of leukocytes did not deviate from control values, whereas the progressors' percentages of heterophils and monocytes were significantly higher (P < 0.05) and of lymphocytes significantly lower (P < 0.05) than those of controls by 14 days postinoculation. Indicative of this was the progressors' heterophil to lymphocyte ratio, which was significantly higher (P < 0.05) than that of controls 14 days post RSV challenge and remained elevated throughout the experiment. These findings suggest that the progressors' immune response is suppressed by proliferation of malignant cells. Therefore, the heterophil to lymphocyte ratio may be used in addition to tumor size to identify those birds that will regress RSV-induced tumors.

Animals↗

PubMedDate not supplied

Apparent selenium toxicity in emus (Dromaius novaehollandiae).

A commercial emu breeder experienced high embryonic mortality during the 1992-93 breeding season, apparently associated with high levels of selenium. The feed was a mixture of catfish food supplemented with a vitamin E and selenium premix. The mixture contained an average of 1.4 ppm selenium. Selenium analysis was conducted on eggs from several hens laid during the period of vitamin and selenium supplementation and after the supplementation was withdrawn. Initial egg selenium levels ranged from 1.2 to 7.1 ppm, with a mean value of 4.2 +/- 0.7 ppm (n = 9). Eggs collected over a 2-month period post-withdrawal contained 2.1 +/- 0.2 ppm selenium (n = 6). Eggs sampled between 2 and 3 months post-withdrawal contained 1.1 +/- 0.1 ppm selenium (n = 4). Egg selenium levels decreased significantly over the 3-month period (P < 0.05) for each individual sample.

Animal Feed↗