Abstract
The immune responses following vaccination and resistance to diseases were compared in male and female meat poultry breeders of the same flock. Female poultry breeders maintained antibody titres to Newcastle disease virus and infectious bronchitis virus up to the fifty-fifth day following vaccination, whereas those of the males declined significantly over the same period of time (P < 0.05). In the same flock, outbreaks of Gumboro disease (60 to 62 days of age), coccidiosis (68 to 74 days of age) and aortic rupture (99 to 112 days of age) produced significantly higher losses in males. Following vaccination against fowl pox by the wing web method, 96.7% of females had a vaccine reaction (vaccine take) compared to none of the males. Immune injuries, following vaccination, were observed in 85% of the males compared to none of the females. The immune injuries included appearance of facial papules, vesicles, and reddish brown to black scabs.