The response of male broiler chickens to diets with various protein contents during the grower and finisher phases

In two trials, each using 960 male broilers from 21 to 42 d of age increasing dietary protein from 175 to 220 g/kg at equal ME increased body‐weight gain from 986 to 1090 g and gain:food ratio from 0·439 to 0·499, while abdominal fat pad weights (40·7 to 35·2 g) and total carcass fat content (140 to 118 g/kg) decreased.2. From 42 to 49 d gain: food ratio increased with increasing protein content, while body‐weight gain and abdominal fat were not affected.3. Broilers fed on the lower‐protein diet from 21 to 42 d showed compensatory growth during the finisher phase (371 versus 331 g gained) and utilised food more efficiently (0·383 versus 0·340 g gained/g food consumed).4. Decisions regarding nutrient concentrations during grower and finisher phases should take into account compensatory growth and food utilisation as well as body‐weight gain, food consumption and carcass composition.