MVSc

A study was conducted with the objective of finding the variations in the cell mediated immunological responses induced by heat / cold stress in cockerels and the role of brahma rasayana (BR) supplementation as an immunopotentiative agent. A total of 144 Gramapriya cockerels having 1 kg bw (4 months) were subjected to heat (40 ± 10C and relative humidity (RH) 80 ± 5 per cent) and cold (4 ±10C and RH 45 ± 5 per cent ) each for 4 consecutive hours per day for 10 days in a controlled environmental chamber (floor space 875 cm2 / bird). Control groups were reared randomly under ambient temperature of 30 ± 10C and RH 65 per cent. The dietary inclusion of BR was done @ 2.0 g/kg bw for 20 days (10 days prior to and during the period of heat / cold stress).
To certain extend the heat stress induced hyperthermia in birds. Heat stress was positively correlated with the plasma corticosterone level in untreated cockerels, whereas exposure to cold and BR treatment resulted in lowered plasma corticosterone concentration.
The phagocytic potential and migratory capability of peritoneal macrophages was found to be enhanced in both heat / cold stress, which were further enhanced by BR supplementation, while the cytotoxicity against L929 cells was decreased in heat / cold stressed cockerels, which were reversed by BR supplementation.
It was noticed that the cutaneous delayed hypersensitivity response in heat / cold stressed untreated cockerels at 24 / 48 h post PHA inoculation got increased by BR supplementation. Similarly, the leucocyte migration inhibition index which was decreased in temperature stress could be reversed by BR treatment.
Administration of BR was found to enhance the proliferation of splenocytes in response to mitogens like PHA and Con A in both heat / cold stress. The mitogenic response of PHA was dose dependent, while that of Con A was not dose specific.
The natural killer cell activity was found decreased by heat / cold stress and enhanced with the supplementation of BR, earlier lysis of target K562 cells were achieved by effector cells.
The antibody dependent cellular cytotoxicity was enhanced in heat / cold stressed cockerels administered with BR on the ninth day, when compared to their untreated counterparts, which was measured from the percentage SRBC lysis.
An earlier antibody dependent complement mediated cytotoxicity was observed on 5th day of the experiment, while the BR supplementation could augment the tumoricidal property through ACC in heat / cold stressed and non-stressed cockerels.
The cockerels under induced heat stress exhibited much diminished cell mediated immune profile when compared to cold stressed and non-stressed birds. In general, most of the immune parameters screened in cockerels under induced cold stress were found to be in par with non-stressed BR treated group. This indicated that there was not much alteration in the immune status of cockerels during cold exposure. Results of the present study also indicated that the dietary supplementation of BR @ 2.0 g/kg bw in poultry could potentiate the immunological insult inflicted by heat stress.