EFFECT OF EARLY HEAT CONDITIONING AND LIGHTING REGIME ON PHYSIOLOGICAL AND IMMUNE RESPONSES OF MUSCOVY DUCKS DURING SUMMER SEASON

The objective of this study was to investigate the beneficial effects of early age thermal conditioning and lighting regime to reduc adverse effects of hot weather condition, especially on the oxidative stress and immune function of Muscovy ducks. Experimental design was a 2 × 2 (4 groups of 160 ducks) during summer season. Ducks were divided into two equal groups. The control group, maintained under normal ambient temperature, the second group were exposed to early age thermal conditioning (exposed to temperature of 39±1°C for 6 h at 5th day of age and then subjected to normal ambient temperature. Each group of the previous groups were divided into subgroups at beginning 4 week of age. The first subgroup was subjected to normal day light (16 h light, 8h dark) and the second subgroup was subjected to intermittent light regime of 4h light 2h dark (make 16h light, 8h dark). Blood samples were collected at 12 weeks of age for assay of some blood parameters.
The obtained results could be summarized as follows:
                Body temperature was significantly decreased by both early-age thermal conditioning or intermittent light regime. Plasma lysozyme concentration of Muscovy ducks were insignificantly increased in early heat exposed group compared to the control group. However, it significantly increased in intermittent light regime group. Corticosterone level and Hetrophil/lymphocyte ratio decreased in both thermally-conditioned and intermittent light groups compared to control group. Plasma malondialdehyde was significantly decreased in early heat exposed group compared to the control group. However, it insignificantly decreased in intermittent light regime group compared to control group. Superoxide dismutase and catalase enzymes increased in both thermally-conditioned and intermittent light groups compared to control group. It is concluded that a combination of early age thermal conditioning and intermittent light regime reduces oxidative stress and improves immune responses and this combination can be considered as bio-stimulation methods for the birds to reduc the negative effects of high ambient temperature.