Interrelationship between methionine and cystine of early Peking ducklings.
A 4 x 5 factorial experiment containing 4 cystine levels (0.325, 0.406, 0.487, or 0.568%) and 5 methionine levels (0.285, 0.385, 0.485, 0.585, or 0.685%) was conducted to evaluate the interrelationship between methionine and cystine in corn-peanut meal diet for Peking ducklings from hatch to 21 d of age. Eight hundred 1-d-old male white Peking ducklings were assigned to 20 experimental treatments. All treatments were replicated 4 times using 10 ducklings per pen. As dietary methionine level increased, weight gain and feed intake increased and then decreased; the quadratic response of weight gain was significant (P < 0.05). The methionine requirement for maximum efficiency of feed utilization (0.585%) was higher than for maximum weight gain (0.485%). According to the quadratic model, the optimal methionine requirement of Peking ducklings from hatch to 21 d of age was 0.481% (95% of the level at maximum response). The plasma uric acid concentration was very low (P < 0.05) when dietary methionine was 0.485%. When dietary methionine was excessive (0.685%), the plasma homocysteine concentration increased (P < 0.05). On the other hand, the cystine requirement of ducklings from hatch to 21 d of age was not more than 0.325%. A high level of cystine (0.568%) depressed weight gain and feed intake (P < 0.05), but cystine supplementation in the diets lowered the plasma homocysteine concentration (P < 0.05). There were no significant interactions between methionine and cystine on growth performance, plasma uric acid, and plasma homocysteine.
Xie
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Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China. Houss@waterfowl.org.cn
Hou
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Huang
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Zhao
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Yu
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Li
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D000821:Animal Feed; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003124:Colorimetry; D003553:Cystine / Q000008:administration & dosage*; D004032:Diet / Q000662:veterinary*; D019587:Dietary Supplements; D004372:Ducks / Q000254:growth & development*; D004435:Eating / Q000502:physiology; D006710:Homocysteine / Q000097:blood; D008297:Male; D008715:Methionine / Q000008:administration & dosage*; D014527:Uric Acid / Q000097:blood; D015430:Weight Gain / Q000502:physiology
D006710:Homocysteine; D014527:Uric Acid; D003553:Cystine; D008715:Methionine