عنوان مقاله [English]
نویسندگان [English]چکیده [English]
BACKGROUND: Changing in protein level and electrolyte balance in diets can be useful in improvement of performance in broilers exposed to heat stress. OBJECTIVES: This experiment was carried out to determine the effects of different levels of protein and electrolyte balance (DCAB) on performance and carcass traits in broiler exposed to heat stress. METHODS: 486 Ross, one-day old broilers were used in a completely randomized design with a 3×3 factorial arrangement in triplicate for a treatment. For performing this, 9 diets were formulated according to NRC recommendation with 3 different protein levels (100, 90 and 80% of NRC recommendations) and electrolyte balance (200, 260 and 320meq/kg). The birds were exposed to heat stress (34±3?C) for 8 hours (10:00 to 18:00). RESULTS: Body weight gain in broilers fed containing 260meq/kg DCAB, were significantly (p<0.05) higher than those fed other levels of DCAB in other periods (starter, grower and total period). The electrolyte balance had significant effect (p<0.05) on feed intake in grower period (14.63gr/day). Dietary protein levels had no significant effect on body weight gain (BWG), feed intake (FI) and feed conversion ratio (FCR) in all periods. There was a significant interaction (p<0.05) between DCAB and protein levels on the BWG an FI (11.5 and 21.11gr/day). Compared to DCAB 320meq/kg, the DCAB 200 and 260meq/kg significantly decreased FCR (0.15 and 0.2, respectively), but FCR did not affect by protein levels. Dietary DCAB had significant effect (p<0.05) on carcass yield (3.25%), breast (1.63%) and relative weights of liver (0.26%) and gizzard (0.56%), but had no significant effect on thigh, heart and abdominal fat. The lower protein level did not affect on carcass traits, with the exception of carcass yield. CONCLUSIONS: 260 meq/kg DCAB and medium 90% protein level of NRC recommendation in heat stress can be used.