Abstract :
An experiment was designed to study the effect of different heat combating practices during acute heat stress on productive and physiological performances of Cobb500 chicks. Total of 540 one-day old of Cobb500 chicks was randomly divided into six equal groups with three replicates (30 birds in each). The first group was subjected to neutral temperature (NT), the second group was under chronic heat stress as a control (CHS), the third group was exposed to early heat acclimation (EHA), the fourth group was exposed to feed restriction (FR), the fifth group was supplemented with 1 g vitamin C/Kg diet (Vit.C), and the six group was treated with a combination of the last three treatments (EFC). It was observed that, CHS group recorded the highest value in respiratory, mortality rate, serum liver enzymes activities (ALT and AST), serum glucose concentrations and the lowest body weight, feed intake, feed conversion ratio, serum concentrations of triiodothyronine (T3) and thyroxine (T4) hormones, serum immunoglobulin concentration, serum lipid profile levels, livability among groups, while, exposed chicks to different heat combating practices: NT, EFC, Vit.C, FR and EHA, respectively, decreased significantly chicks mortality, serum corticosterone concentration hormone and improved the livability percentages, body weight, feed intake, feed conversion ratio, serum immunoglobulin concentrations and had better results for serum ALT and AST activities. Furthermore, EFC and NT groups recorded the highest significant EPEI values (18.38 and 17.48) respectively, and serum concentrations of triiodothyronine (T3) and thyroxine (T4) hormones compared to the other groups. It can be concluded that EFC treatment showed the best practical method compared to the other groups to enhance the production performance and immunity status followed by T5, T4 and T3.
Therefore, these methods can be applied in broilers farms to increase the economic return
Keyword :
Acute heat stress; Broiler Chicken; and physiological changes