Natural humoral immunity in turkey breeders and broilers, healthy and with hereditary muscular dystrophy, reared under comfortable or stressful microclimatic conditions.

The aim of the present study was to investigate the co-influence of hereditary muscular dystrophy (HMD) and microclimatic stress factors on blood serum lysozyme concentrations and alternative pathway of complement activation (APCA) in turkey breeders and turkey broilers. The HMD prevalences in Lightweight laying (LL) and Heavyweight bred-for-meat (HM) 180 day old turkey breeders were 5.0% and 7.1% respectively. The lysozyme concentrations and APCA were measured in 20 healthy controls (10 LL and 10 HM) and in all diseased breeders. These 2 parameters were strongly increased in diseased LL and HM breeders compared to the corresponding healthy controls and they were significantly lower in the HM line than in the LL one (P < 0.01). In 52 day old turkey broilers, HMD has been identified in 11.7% of birds reared under comfortable housing conditions and in 13.3% of birds reared under stressful conditions (high temperatures and ammoniac concentrations). The 2 non specific immune parameters were determined in groups of 10 broilers each with or without muscular dystrophy and reared under favourable or unfavourable microclimatic conditions. Lysozyme concentrations and APCA values were dramatically increased in diseased broilers compared to the respective controls and they were significantly depressed in birds reared under an ambient stress compared to broilers reared under comfortable conditions (P < 0.01 for healthy controls and P < 0.05 for diseased animals). These results clearly indicate that the hereditary muscular dystrophy activated non-specific defence systems and that both high ambient temperatures and ammoniac concentrations had a negative impact on the non-specific immunity.