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Assessment of energy and amino acid diet formulation in growing Ross broilers


This study investigated the effect of low and high protein diets formulated based on net energy (NE) and metabolized energy (ME) on live performance and carcass characteristics of 7-32 day old Ross 708 broilers. The NE equation can be described as the ME minus heat increment. Once NE is predicted, important factors must be taken in consideration in formulation, since formulation based on NE can enhance the energy efficiency and provide closer energy needs for production and maintenance. Birds were placed in four tunnel ventilated, solid-sided colony houses. Lighting and temperature regimes followed the primary breeders recommendation, and feed and water were provided ad libitum. Three hundred and eighty-four females and male broilers (Ross 708) were randomly allocated in four poultry houses with two houses for females and two houses for males (one hundred and ninety-two birds per house). Each house had sixteen pens (3 x 4 feet) of birds which were fed one of four different experimental treatments (n=4 or 8). The treatments diets were 1) (22.5% CP, 3,100 kcal/kg ME, 2,553 kcal/kg NE). 2) (20.2% CP, 3,100 kcal/kg ME, 2,553 kcal/kg NE). 3) (22.5% CP, 3,049 kcal/kg ME, 2,500 kcal/kg ME. 4) (20.2% CP, 3,049 kcal/kg, ME, 2,500 kcal/kg NE). House x treatment interactions occurred for male live performance; thus, male live performance was not combined by house. Differences in male and female live performance as affected by diet did not occur. Although processing differences were minimal, carcass fat in females was affected by diet. Carcass fat was decreased in female broilers fed the highest CP diet (P < 0.03), and an interaction between CP and energy occurred for carcass fat (P < 0.10) in female broilers.