Fowl typhoid in cocks. Age-dependent susceptibility of the birds disease
2006
Chacana, P.A. | Terzolo, H.R.,Instituto Nacional de Tecnologia Agropecuaria, Balcarce (Argentina). Dept. de Produccion Animal
This work was carried out to assess experimental models for production of fowl typhoid in cocks. In order to standardize the virulence of the challenge strain, Salmonella gal-linarum INTA 91, a limited and fixed number of passages through artificial media were made. Twenty-four and 58 week-old cocks were challenge with S. gallinarum by gavage into the crop and kept in observation during 3 weeks. Mortality was daily recorded. Cocks used in this trails were not exposed to any reproductive pressure. When the cocks were 24 weeks old, the disease was produced when they were orally challenged with 10**10 or more colony-forming units per chicken, Reed and Muench's LD50 of S. gallinarum value was estimated as 3.16 x 10**10 CFU per cocks. Cocks of 58 weeks of age were more susceptible to infection: the LD50 value was estimated as 1.75 x 10**7 CFU per cock. In both trails, fowl typhoid signs started after 5-15 days after challenge. The disease was acute and septicemia was consistently produced. All challenged chickens that became ill showed anorexia, somnolence, and depression. None of the diseased cocks or hens had diarrhea. Animals died 2 or 3 days after the onset of symptoms. Enumeration of S. gallinarum in livers was around 8 log10 CFU per gram, regardless the age of the examined chickens
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