Effects Of Methionine Sources And Levels On Growth Performance,Feather Development,Intestinal Health And Antioxidant Ability In Meat Ducks

In this paper,two trials aimed at investigating the effects of the addition of solid methionine（DL Methionine,DLM）to liquid methionine hydroxy analogue（2-hydroxy-4-（methylthio）butyric acid,HMTBA）under deficient and satisfying conditions on the growth performance,carcass traits,feather development,intestinal health and the antioxidant ability of meat ducks were conducted to evaluate the differences in the efficacy of solid versus liquid methionine,It provides theoretical basis and technical support for the rational and efficient utilization of methionine and its hydroxyl analogues in meat duck feed.Experiment 1:Effects of methionine sources and levels on growth performance,carcass traits and feather development of 15-42d meat ducksThe assay was performed using 5×2+1 factorial design setting a negative control group（NC,methionine level 0.22%）without added methionine;Equimolar addition of two methionine sources:solid methionine（DLM）and liquid methionine（HMTBA）at five methionine addition levels;DLM or HMTBA（methionine levels 0.34%,0.41%,0.49%,0.56%,0.63%）were added on the basis of the control group without methionine supplementation that met the requirements of 80%,90%,100%,110%,120%of methionine for 11 treatments,6replicates of each treatment,and 20 ducks of each replicate for a total of 1320 Cherry Valley ducklings.The experimental diets were based on the corn soybean meal type,and the nutrient level setting was performed with reference to the standard of duck feeding in China（NY2122-2012）as well as the results of previous studies in our laboratory.The nitrogen content of the diets for different treatments was adjusted with alanine,and the addition of solid or liquid methionine was adjusted with systemic bran,and equal amounts of lysine,threonine,and tryptophan were maintained in all groups.The test started at 15 days of age in meat ducks and ended at 42 days of age.Meats 1-14 days old were fed the same ducklings,and 15 days old were fed the test diets after regrouping according to the principle of no difference in body weight.The results showed that:1)Compared with the no methionine group,the addition of DLM with HMTBA both improved（P<0.05）the growth performance,carcass traits（increased pectoral muscle rate and decreased abdominal fat rate）and feather growth(4^th primary wing feather length,feather weight and index)（P<0.05）of 15-42-day-old meat ducks.2)Relative to HMTBA,DLM significantly reduced the feed weight ratio and stage feed intake（P<0.05）.The abdominal fat weight of meat ducks at 42 d was significantly decreased as the level of dietary methionine supplementation increased.3)The dietary methionine level had a significant effect on meat feather weight and indexes（P<0.05）,and the addition level of methionine was 0.27%,that is,the methionine requirement was the recommended level（0.49%）for the standard of rearing in Chinese ducks,and the development of meat duck feathers was the best.4)By biological titer analysis,we found that HMTBA relative DLM titers were 98.95%and 95.12%using 42 d BW and 15-42 D BWG as indicators;Using the 42-d feather index as an index,the HMTBA relative DLM titer was 105.32%.The results of this test suggested that DLM with HMTBA could improve the growth performance and carcass traits of meat ducks compared to no methionine addition group,and HMTBA was superior to DLM in promoting feather development in meat ducks.Experiment 2:Effects of methionine sources and levels on growth performance,feather development,intestinal health and antioxidant ability of 1-42d meat ducksThe test design and feed formulation principles were the same test,but the test stage was divided into 1-14 days old and 15-42 days old,and a total of 11 treatments,8 replicates of each treatment and 10 ducks per replicate,were tested,resulting in a total of 880 Sakura Valley ducklings.The serum,liver,pectoral muscle,leg muscle,intestine,hair follicles of the NC group without methionine supplementation,DLM（80/100/120）,HMTBA（80/100/120）were collected at 42 days of age,and a total of 7 groups of meat ducks（1 in each replicate）were examined for antioxidation,intestinal health,and hair follicle development indicators.The results showed that:1)Methionine supplementation（HMTBA and DLM）improved the growth performance（P<0.05）,carcass traits（increased the rate of pectoral muscle（P<0.05）and decreased the rate of abdominal fat（P<0.05）of meat ducks compared with no methionine group,and the addition of HMTBA significantly increased the diameter of pectoral muscle fibers of meat ducks at 42 d.2）Compared with DLM,HMTBA increased the 1-14d feed intake of meat ducks（P<0.05）;However,there were no significant differences in other growth performance,carcass traits,meat routine quality,gastrointestinal development and p H between the two groups（P>0.05）.3)When the methionine level reached the recommended level of the standard of rearing for Chinese ducks（0.49%）and above,the meat duck feather development was significantly better than that in the methionine deficient group（P<0.05）;Moreover,HMTBA exerted better effects on feather development than DLM（P<0.05）,and HMTBA at the 0.49%level significantly increased the amount of gene expression of EGF in meat duck skin（P<0.05）.4)HMTBA at 0.63%significantly（P<0.05）increased the expression of intestinal barrier genes ZO-1,Claudin-1 as well as Occludin in the ileal mucosa of meat ducks at 42 d compared with the non supplemented methionine group.The ileal p H in the group fed methionine level of 0.49%was the lowest（P<0.05）.5)Compared with the no methionine group,both HMTBA and DLM supplementation in the diet significantly increased the superoxide dismutase activity（P<0.05）and decreased the malondialdehyde level（P<0.05）in the serum of meat ducks 42 d p.i.Glutathione peroxidase activity in pectoral muscle reached the highest level when methionine level was 0.49%（P<0.05）.The glutathione content in the tissues of meat ducks increased significantly（P<0.05）with the level of methionine supplementation,and was higher in the DLM supplemented group than in the HMTBA group（P<0.05）.However,superoxide dismutase activity as well as glutathione peroxidase activity in the HMTBA added group were significantly higher than those in the DLM group（P<0.05）.6)The suitable levels of methionine identified by 1-42-day-old feed weight ratio,15-42-day-old feed weight ratio using HMTBA as methionine source were 0.558%,0.561%;The suitable levels of methionine identified by the 1-42-day-old feed weight ratio and 15-42-day-old feed weight ratio of meat ducks using DLM as methionine source were 0.559%,0.520%,respectively.In conclusion,the addition of both HMTBA and DLM improved the growth performance,carcass traits and muscle deposition of meat ducks and decreased the abdominal fat deposition,and no significant differences were found between the two methionine sources;The promoting effect of HMTBA on plumulaceous feather development was better than that of DLM;Both methionine source and level had significant effects on the antioxidant ability of meat ducks,and DLM could be effectively used for glutathione synthesis,while HMTBA was more beneficial to the activities of antioxidant related enzymes.