Growth performance, nutrient digestibility, metabolizable energy, and intestinal morphology of growing turkeys fed diet supplemented with arginine

A 8-wk feeding experiment was conducted to investigate the effect of dietary supplementation with Arg on growth performance, nutrient digestibility, metabolizable energy, and intestinal morphology of growing turkeys. A total of one hundred and eighty 56-d-old male grower turkeys were weighed individually and randomly assigned to 1 of 3 dietary treatments with 6 replicate pens and 10 turkeys per pen in a completely randomized design. Dietary treatments consisted of basal diets supplemented with 0, 0.5, and 1.0 g Arg/kg. Growth response was measured during the grower (d 56–84) and finisher (d 84–112) phases, while nutrient digestibility, metabolizable energy, and intestinal morphology were measured at d 84 and 112. Arginine supplementation had no effect on growth response during the grower phase. During the finisher phase, feed conversion ratio decreased initially as Arg supplementation increased from 0 to 0.5 g/kg, but it increased with the 1.0 g Arg/kg (quadratic, P=0.028). At d 84, grower turkeys fed diets supplemented with 1.0 g Arg/kg had greater (linear, P<0.001) apparent dry matter, crude protein, and ether extract digestibility. At d 84, greatest apparent metabolizable energy, nitrogen corrected apparent metabolizable energy, and true metabolizable energy values were obtained with grower turkeys fed diet supplemented with 0.5 g Arg/kg (quadratic, P<0.001). At d 84, duodenum, and ileum villus height in grower turkeys increased linearly, and quadratically (P<0.001) with increasing Arg supplementation. Dietary supplementation with Arg reduced the apical widths in duodenum (linear, P=0.003; quadratic, P<0.001), jejunum (linear and quadratic, P<0.001), and ileum (linear, P=0.010; quadratic, P=0.004) of grower turkeys. At d 112, jejunum villus height (quadratic, P=0.042), and ileum villus height (linear, P=0.022; quadratic, P=0.042) of finisher turkeys increased, while duodenum apical widths reduced (quadratic, P=0.033) with increasing Arg supplementation. In conclusion, Arg supplementation showed a linear improvement in nutrient digestibility of grower turkeys at d 84, increased nutrient absorption in grower, and finisher turkeys as indicated by increased intestinal villus height at d 84, and 112. Furthermore, dietary supplementation with 0.5 g Arg/kg promoted a quadratic improvement in feed conversion ratio of finisher turkeys, and metabolizable energy values of grower turkeys at d 84.