An experiment was conducted to determine whether feeding
semduramicin at recommended levels (25 mg/kg) would affect the broiler chicken's response to
dietary protein; and to determine whether
protein source (all vegetable, corn and soybean meal, vs 12% high animal
protein ingredients) would affect the response to
semduramicin.
Semduramicin was fed to half of 1,584 male Ross x Ross broilers in floor pens during the growing phase (18 to 35 d). Three
protein fortification levels were also fed with
protein and
amino acid minimum restrictions at 80, 100, and 120% of NRC (1994) recommendations. At 35 d,
semduramicin was found to cause a slight growth depression in
body weight gain only when low
protein levels were fed (P = 0.051). After a 7-d withdrawal period, compensatory gains occurred (P = 0.006) such that there was no interaction effect of
semduramicin by
protein level for 42-d
body weight (P = 0.75). Birds fed the diets containing high animal
protein were slightly heavier than those fed control diets containing all-
vegetable protein (2.40+/-0.02 vs 2.36+/-0.01 kg/bird; P = 0.059).
Semduramicin feeding did not affect feed consumption (2.43+/-0.03 vs 2.40+/-0.02 kg per bird during the growing period when it was fed) so that overall feed conversion ratios were identical to two decimal places (1.90+/-0.02 vs 1.90+0.02). Neither did
semduramicin affect feathering score or weight of the No. 8 primary feather, except that feather weight tended to be improved by
semduramicin feeding with the diets containing ingredients high in animal
protein (P = 0.067).