Effect of excess methionine and methionine hydroxy analogue on growth performance and plasma homocysteine of growing Pekin ducks.
One experiment was conducted to study the effect of excess dl-methionine (DLM) and dl-2-hydroxy-4-methylthiobutanoic acid free acid (dl-HMB-FA) on duck growth. One-day-old male white Pekin ducklings were fed common starter diets from hatch to 21 d of age and then fed the experimental diets from 21 to 42 d of age. Three hundred twenty 21-d-old birds were allotted to 40 raised wire-floor pens with 8 birds per pen according to similar pen weight. There were 5 dietary treatments that included a methionine-adequate control diet and control diets supplemented with 2 levels of dry DLM (1 or 2%) or 2 equimolar levels of liquid dl-HMB-FA (1.13 or 2.26%). Each dietary treatment was replicated 8 times. At 42 d of age, weight gain, feed intake, and gain/feed were measured and plasma was collected to analyze homocysteine. Compared with ducks fed control diets, excess DLM or dl-HMB-FA supplementation reduced weight gain and feed intake of birds significantly. However, on the equimolar basis, at 1 or 2% supplemental methionine activity, dl-HMB-FA was less growth-depressing than DLM. According to the growth response to excess methionine, the tolerable upper limit of dietary methionine for growing ducks may be less than 1.38% when the methionine level of the control diet (0.38%) was considered. On the other hand, plasma homocysteine was elevated markedly when 2% DLM or 2.26% dl-HMB-FA was added to control diets, but plasma homocysteine of ducks fed 2.26% dl-HMB-FA supplemented diets was lower significantly than birds fed equimolar DLM-supplemented diets, which indicated the toxicity of excess methionine sources and less toxicity of dl-HMB-FA relative to DLM.
Xie
M
M
Institute of Animal Science, Chinese Academy of Agricultural Sciences, Beijing, China 100094.
Hou
S S
SS
Huang
W
W
Fan
H P
HP
D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D004372:Ducks / Q000097:blood / Q000254:growth & development*; D006710:Homocysteine / Q000097:blood*; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015430:Weight Gain / Q000187:drug effects
D006710:Homocysteine; C008391:alpha-hydroxy-gamma-methylmercaptobutyric acid; D008715:Methionine