Methionine and cystine requirements of slow- and fast-feathering male broilers from zero to three weeks of age.
Two experiments were conducted with fast- (Ross x 3F8) and slow- (Ross x 308) feathering broiler males from 0 to 3 wk of age to determine Met and Cys requirements. A corn-soybean meal basal diet was formulated to be deficient in Met and Cys but was adequate in all other nutrients (22.0% CP; 3,050 kcal ME/kg). In experiment 1, diets contained 0.50% dietary Cys with 0.35, 0.40, 0.45, and 0.50% total Met. Feed conversion (FC) of slow- and fast-feathering males improved in a similar manner to 0.50% Met (linear, P < 0.05). Nitrogen retention measured from 20 to 21 d of age optimized at 0.46% Met (quadratic, P < 0.01), regardless of feathering rate. Experiment 2 examined the response to feeding 0.35, 0.40, 0.45, and 0.50% total Cys in diets having total Met at 0.45%. Increasing Cys improved FC that optimized at 0.40% with fast-feathering birds (quadratic, P < 0.01), whereas slow-feathering broilers were not responsive. Nitrogen retention measured from d 20 to 21 did not indicate a difference attributable to feathering but a Cys optimization at 0.43% with both broiler sources. Present experimentation indicates a Met requirement approximating 0.50% is appropriate for broilers 0 to 3 wk of age, regardless of feather rate; however, the estimated Cys requirement for slow-feathering males (0.39%) was less than for fast-feathering (0.44%) males.
Kalinowski
A
A
Auburn University, Poultry Science, Auburn, Alabama 36849, USA. kalina1@auburn.edu
Moran
E T
ET
Wyatt
C
C
D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn; D002645:Chickens / Q000254:growth & development*; D003553:Cystine / Q000008:administration & dosage / Q000494:pharmacology*; D005241:Feathers / Q000254:growth & development; D008297:Male; D008715:Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D009751:Nutritional Requirements
D003553:Cystine; D008715:Methionine