过量蛋氨酸对7～28日龄北京鸭生长性能和血液指标的影响

Effects of Excess Methionine on Growth Performance and Blood Parameters of Peking Ducks during 7 to 28 Days of Age

本试验旨在探究饲粮中添加过量蛋氨酸对7~28日龄北京鸭生长性能和血液指标的影响,并评估7~28日龄北京鸭饲粮中蛋氨酸的最大安全限量。试验选取7日龄健康雄性北京鸭252只,依据体重基本一致原则,随机分为6个组,每组7个重复,每个重复6只鸭。各组分别饲喂蛋氨酸水平为0.48%、0.73%、0.98%、1.23%、1.48%和1.73%的饲粮。其中,正常饲粮蛋氨酸水平为0.48%,满足育雏期北京鸭正常生长需要。试验期21 d。结果表明:1)与饲粮蛋氨酸水平为0.48%时相比,当饲粮蛋氨酸水平为0.98%及以上时,试验鸭末重、平均日采食量和平均日增重均显著降低(P<0.05),且随蛋氨酸水平的升高进一步显著降低(P<0.05)。各组间料重比无显著差异(P>0.05)。2)与饲粮蛋氨酸水平为0.48%时相比,当饲粮蛋氨酸水平为0.98%及以上时,血浆总胆红素含量显著升高(P<0.05);当饲粮蛋氨酸水平为1.23%及以上时,血浆高半胱氨酸含量显著升高(P<0.05),且随蛋氨酸水平的升高而进一步显著升高(P<0.05);当饲粮蛋氨酸水平为1.73%时,血浆谷丙转氨酶和乳酸脱氢酶活性显著升高(P<0.05)。3)与饲粮蛋氨酸水平为0.48%时相比,当饲粮蛋氨酸水平为0.98%及以上时,血液血红蛋白含量和平均红细胞血红蛋白浓度均显著降低(P<0.05);当饲粮蛋氨酸水平为1.23%及以上时,血液平均红细胞血红蛋白含量显著降低(P<0.05);当饲粮蛋氨酸水平为1.48%及以上时,血液红细胞体积分布宽度和平均红细胞体积显著升高(P<0.05),血液红细胞计数显著降低(P<0.05)。4)以平均日增重为评价指标,采用折线模型估测7~28日龄北京鸭饲粮蛋氨酸的最大安全限量为0.87%。由此可见,饲粮中添加过量蛋氨酸可显著抑制7~28日龄北京鸭的生长,导致血液指标异常。7~28日龄北京鸭饲粮蛋氨酸的最大安全限量为0.87%。

This experiment was conducted to investigate the effects of excess methionine on growth performance and blood parameters of Peking ducks during 7 to 28 days of age, and to determine the maximum safe level of methionine of Peking ducks during 7 to 28 days of age. A total of 252 seven-day-old healthy male Peking ducks were randomly allotted to 6 groups with 7 replicates per group and 6 ducks per replicate according to similar pen weight. The ducks in 6 groups were fed diets with methionine levels of 0.48%, 0.73%, 0.98%, 1.23% , 1.48% and 1.73%, respectively. The diet with methionine level of 0.48% was a methionine-adequate diet for ducks. The experiment lasted for 21 days. The results showed as follows： 1） compared to the dietary methionine level of 0.48%, when dietary methionine level was 0.98% or above, the final body weight （FBW）, average daily gain （ADG） and average daily feed intake （ADFI） of ducks were significantly decreased （ P 〈 0.05 ）, and the FBW, ADG and ADFI were significantly decreased with methionine level increased （ P 〈 0.05 ）. However, there was no significant difference on the ratio of feed to gain （F/G） among six groups （ P 〉 0.05）. 2） Compared to the dietary methionine level of 0.48%, when dietary methionine level was 0.98% or above, the plasma total bilirubin content was significantly increased （ P 〈0.05）; when dietary methionine level was 1.23% or above, the plasma homocysteine content was significantly increased （ P 〈0.05）, and it was significantly increased with methionine level increased （ P 〈0.05）; when dietary methionine level was 1.73% , the activities of glutamic-pyruvic transaminase and lactic dehydrogenase in plasma were significantly increased （ P 〈0.05）. 3） Compared to the dietary methionine level of 0.48%, when dietary methionine level was 0.98% or above, the blood hemoglobin content and mean corpuscular hemoglobin concentration were significantly decreased （ P 〈0.05）; when dietary methionine level was 1.23% or above, the blood mean corpuscular hemoglobin content was significantly decreased （ P 〈0.05）; when dietary methionine level was 1.48% or above, the blood red cells volume distribution width and mean corpuscular volume were significantly increased （ P 〈 0.05 ）, while the blood red cell count was significantly decreased （ P 〈0.05）. 4） According to broken-line regression analysis, the maximum safe level of methionine for ADG in Peking ducks during 7 to 28 days of age was 0.87%. In conclusion, dietary excess methionine can inhibit the growth of Peking ducks during 7 to 28 days of age and cause in abnormal of blood parameters. The maximum safe level of methionine of Peking ducks during 7 to 28 days of age is 0.87%.