Interrelationship between methionine and cystine of early Peking ducklings

Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China. Houss@waterfowl.org.cn

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.

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				M. Xie, S. S. Hou, W. Huang, and H. P. Fan Effect of Excess Methionine and Methionine Hydroxy Analogue on Growth Performance and Plasma Homocysteine of Growing Pekin Ducks Poult. Sci., September 1, 2007; 86(9): 1995 - 1999. [Abstract] [Full Text] [PDF]