Does excess dietary protein improve growth performance and carcass characteristics in heat-exposed chickens?

The effects of two environmental temperatures (22 and 32 C, constant) and f ive dietary protein contents (10 to 33% CP) were investigated in 4- to 6-wk -old broiler chickens. High ambient temperature reduced growth rate, feed e fficiency, and breast muscle proportion and increased abdominal fat proport ion. Irrespective of ambient temperature, increasing dietary protein conten t improved growth performance and carcass characteristics. At 32 C, there w as a greater heterogeneity of the data, and bird responses were lower than at 22 C. We concluded that under conditions of chronic heat exposure, diets containing the highest protein levels, 28% and 33% compared with 20% CP, s lightly improved chick performance. However, the effect was low and, in our experimental conditions, modifying dietary protein supply (variations in t he total quantity of protein) is not sufficient to help broilers to withsta nd hot conditions.