ABSTRACT
Changing in protein level and electrolyte balance in diets can be useful in improvement of performance in broilers exposed to heat stress. 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. 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]. 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. 260 meq/kg DCAB and medium 90% protein level of NRC recommendation in heat stress can be used