Effect of early heat exposure and feeding system on physiological response and productive performance of duckling under heat stress conditions

Abstract

Two experiments were carried out at the Research Station for Waterfowls at EI-Serw of the Animal production Research Institute, Agriculture Research Center. One day-old Muscovy and Domyati ducks (200\breed) were used in this study from March to May 200 I. The first experiment was to designed determine the possibility of improving the productive performance of ducks reared under hot ambient temperature by using heat acclimated at early age. both Muscovy and Domyati ducks were divided randomly into three groups in (40 birds/group). Group I (control group), group 2 (early heated exposure group), group 3 (heat stressed group). The second experiment was conducted to the possibility of acclimating birds to high ambient temperature by fasting. The results showed that SDS electrophoretic pattern of proteins in samples liver and spleen of Muscovy and Domyati ducks after subjected to heat stress (42-43 oc for 4h) at 12 weeks of age found that heat stress caused activation in the expression of HSP families (l-ISP 90, and 70 kDa). Early heat exposure and fasting 24h caused hyperactivation in the expression of HSP families (HSP 90, and 70 kDa). Rectal temperature after exposure of heat stress was higher in heat stressed ducks than control ducks at 8 and 12 weeks of age Early heat exposure and fasting 24h caused lower in rectal temperature. Heat stress caused a reduction in plasma total protein, albumin and A\G ratio than control ducks at 8 and 12 weeks of age. Early heat exposure and fasting 24h caused higher in these traits. The plasma AST and ALT activity significantly increased in the birds exposed to heat stress compared to control birds. Early heat exposure and fasting 24h caused lower in the level of AST and ALT. Hematocrit % decreased in heat-stressed ducks than control birds hematocrit % in early heat exposure and fasted (48h) ducks were significantly lower than the other groups at 12 weeks of age during heat stress.. Plasma T, level was lower in early heat exposure and fasted (48h) birds than fasted 24h groups during heat stress, while in fasted (24h) birds slightly decreased insignificant in level of T3 than control group at 8 and 12 weeks of age during heat stress. Early heat exposure and fasting 24h caused higher body weight. body weight gain. feed conversion. carcass weight percentage, giblets percentage, dressing percentage, and edible pans percentage compared to the other groups at 8 and 12 weeks of age.