Abstract

Aim: This study was aimed to elucidate the changes in serum testosterone profile and some reproductive parameters in commercial ISA Brown cocks experimentally infected with Salmonella Gallinarum.  

Method and materials: A total of 40 ISA Brown cockerels, unvaccinated against fowl typhoid, but vaccinated against other infectious diseases such as Newcastle disease, Infectious bursal disease and fowl pox, were purchased from a reputable farm and brooded for four weeks and reared to 18 weeks of age and housed in deep litter system and managed intensively in the Poultry Research Pen of the Veterinary Teaching Hospital, ABU, Zaria. After attainment of reproductive age (23 weeks), the cocks were randomly allocated into two groups: infected and control of 20 birds each. Each bird in the infected group was administered orally 1ml inoculum containing 9.0 x 108 CFU/ml Salmonella Gallinarum, while birds in the control group were administered 1ml of distilled water each. Blood samples were collected on days 0, 4, 7, 14, 21, 28, 35 and 42 post infection (pi) in both groups and the harvested serum samples were used to analyse for serum concentration of testosterone. The cocks in both groups had their semen characteristics determined weekly for sixweeks post infection. Cocks showing a typical clinical signs of fowl typhoid were humanly sacrified (embolism in the heart). Gross lesions, observed, were recorded, while specimens from liver, spleen and other organs were fixed in 10% neutral buffered formalin, while the testes were fixed in Bouins solution.

Results: Following infection of the infected birds, classical signs of fowl typhoid were observed. The clinical signs were moderate (24.7%) with mortality and morbidity of 37% and 50%, respectively. Serum testosterone concentration (1483±645 pg/ml) in the infected group significantly decreased (p < 0.05) from day 7 to lowest value of 520±394 pg.ml on day 21 pi. The control group had better semen colour, higher semen volume and better spermatozoa concentration than the infected cocks. The infected Isa brown cocks had higher percentage total spermatozoa abnormalities than the control group.

Conclusion: It was concluded that Salmonella Gallinarum can reduce serum testosterone concentration, semen volume, semen concentration, sperm motility and among others in ISA Brown cocks thereby resulting in reduced fertility.

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