INVESTIGADORES
CHACANA Pablo Anibal
artículos
Título:
Fowl typhoid in cocks. Age dependent susceptibility of the birds´ disease
Autor/es:
CHACANA, P. A.; TERZOLO, H. R.
Revista:
ADVANCES IN AGRICULTURAL SCIENCES
Referencias:
Lugar: Szcezin, Polonia; Año: 2006 p. 13 - 18
Resumen:
This
work was carried out to assess experimental models for production of fowl
typhosis in cocks and hens. In order to standardize the virulence of the
challenge strain, Salmonella gallinarum
INTA 91, a
limited and fixed number of passages through artificial media were made. Chickens were challenged
with S. gallinarum by gavage into the crop and kept in observation
during 3 weeks. Mortality was daily recorded. Susceptibility of 24 week-old
cocks and laying hens of the same age was compared. The disease was produced
when cocks where orally challenged with 1010 or more colony-forming
units (CFU) per chicken; Reed and Muench´s LD50 of S. gallinarum value was estimated as
3.16 x 1010 CFU per cock. In
contrast, almost all the hens of the same age died when challenged with 105
CFU onwards. The higher susceptibility of these hens can be explained by their
egg production stress while the cocks used in these trials were not exposed to any
reproductive pressure. Cocks of 58 weeks of age were more susceptible to
infection: the LD50 value was estimated as 1.75 x 107 CFU
per cock. In all trials, fowl typhosis signs started after 5 to 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 or sex of the
examined chickens.