The comparative susceptibility of commercial and Nigerian indigenous chicken ecotypes to Salmonella gallinarum infection
This study was to evaluate the possible genetic resistance of exotic and indigenous chicks to Salmonella gallinarum. A total of 72 nine weeks-old chicks were used for the study. The Fulani ecotype (Fulani smooth feathers - FSF), Yoruba ecotype (Yoruba smooth feathers - YSF), and the Exotic breed (Nera Black) chicks were infected with a dose of S. gallinarum (8.3 x 106 CFU) and were observed for 16 days. Evaluation of resistance was based on clinical signs, mortality, pathology, leukocyte count, bacterial count from liver and spleen of infected chicks. The highest peak for clinical signs in S. gallinarum infected chicks coincides with highest mortalities recorded on day 11-12 dpi and bacterial count of both liver and spleen on day 8. The lymphocytes count declined on day 8 for all the experimental chicks except for the exotic breed. There was no significant difference between the bacterial counts of the different groups on day 8. In S. gallinarum infected chicks, 94.4% of all the chicks showed clinical signs after infection, the exotic breed showed a prolonged clinical signs while the Yoruba ecotype showed the least. 87.5%, 80.0% and 37.5% mortality were recorded in the exotic breed, Fulani and Yoruba ecotypes respectively. The study showed that the exotic chicken (Nera Black) was more susceptible to Salmonella gallinarum infection. It also indicated that within the ecotypes in Nigeria, Fulani ecotype was more susceptible to Salmonella gallinarum infection than the Yoruba ecotype. The lower clinical signs and mortality observed in Yoruba ecotype indicated a resistance of the ecotype to S. gallinarum infection.
Keywords: Ecotypes, Nigerian Indigenous chicken, Salmonella gallinarum infection.