Effects Of Intermittent Cold Stimulation On Performance, Meat Quality, Immunity And Antioxidative Function Of Broilers

The study aimed to investigate the effects of intermittent cold stimuli on performance, meat quality, immunity and antioxidative function of broilers. Three hundred and sixty (360) of1d AA broilers were housed in artificial climate chambers which automatically control room temperatures. The birds were divided into five treatments with intermittent cold stimulations (ICS) conditions of-3℃1h (3℃below normal temperature and1h exposed to cold daily),-3℃3h,-3℃5h-3℃24h and0℃0h (control group). Cold exposure started at8d of age and finished at21d of age (lasting for two weeks). Measurements for performance, meat quality (meat color,45minpH and24hH after slaughtered, drip loss and cooking loss), immunity (immune organ indices, antibodies of1gA,1gM,1gG and cytokines of IL-2, IL-4, IL-6, IFN-y in serum), free radicals (H2O2, MDA, NOS) and antioxidative functions (T-AOC, SOD, GSH-PX) were taken at8,15,22and42d of age. The results showed as follows:1) For performance, average daily feed intake, average daily weight gain, feed conversion rate, slaughter weight, abdominal fat rate were not affected by ICS in all experimental treatments (P>0.05). Survival rate of the birds in ICS groups was relatively higher than that of control group but the difference was not significant (P>0.05).2) For meat quality, meat color (L*, a*, b*),45minpH and24hH after slaughtered, drip loss and cooking loss were not affected by ICS in all experimental groups (P>0.05).3) For immunity, thymus, spleen and bursal indices were not affected by ICS but the indices showed significant variations over time in response to ICS treatments as the experiment progressed (P<0.05). ICS enhanced thymus index and bursal index. Only serum1gA was found to be affected by ICS (P<0.05) but not for IgG and IgM (P>0.05). The antibodies of IgA, IgG, IgM showed significant variations over time in response to ICS treatments as the experiment progressed (P<0.05). ICS enhanced IgA and IgM level in blood. Cytokines of IFN-y was found to be affected by ICS (P<0.05) but not for IL-2, IL-4and IL-6(P>0.05). IL-2, IL-4, IL-6and IFN-y showed significant variations over time in response to ICS treatments as the experiment progressed (P<0.05). ICS enhanced IL-4, IL-6and IFN-y level in serum.4) For free radicals and antioxidant functions, NOS was found to be affected by ICS (P<0.05) but not for H2O2and MDA (P>0.05). MDA and NOS showed significant variations over time in response to ICS treatments as the experiment progressed (P<0.05) but not for H2O2(P>0.05). ICS reduced serum H2O2and NOS. SOD and GSH-PX were found to be affected by ICS (P<0.05) but not for T-AOC (P>0.05).T-AOC, SOD and GSH-PX showed significant variations over time in response to ICS treatments as the experiment progressed (P<0.05).ICS enhanced serum SOD and GSH-PX activities.It can be concluded that the results of the study suggest that appropriate cold stress such as intermittent cold exposure would enhance immunity and antioxidant function of broilers and has no adverse effect on performance and meat quality of broilers. Appropriate cold stimulation could have positive effects on broilers. With comparing comprehensively, the condition of-3℃3h is better and the data in present study may provide an available information for broiler farming that may benefit broiler welfare in a farming system in the future.