Dietary supplementation with 2-hydroxy-4-methyl(thio)butanoic acid and DL-methionine improves productive performance,egg quality and redox status of commercial laying ducks

This experiment aimed to study the effects of supplemental methionine sources,2-hydroxy-4 methyl(thio)butanoic acid(HMTBa)and DL-Methionine(DL-Met),on productive performance,egg quality,and redox status of laying ducks.A total of 792 healthy 25-wk-old Longyan laying ducks with similar body weights were randomly allotted to 11 treatment groups.Each treatment group had 6 replicates of 12 ducks.The trial lasted for 16 wk.Ducks were fed a basal deficient diet(Met:0.24%;Met+Cys:0.51%)or supplemented with DL-Met or HMTBa at 0.05%,0.12%,0.19%,0.26%,and 0.33%of diet,respectively.Compared with the basal diet,supplementation with either DL-Met or HMTBa increased the average egg weight,egg mass,and decreased feed to egg ratio during the whole trial period(P<0.05).Albumen weight and its ratio to total egg weight were increased,but yolk and shell ratio,albumen height,Haugh unit and shell breaking strength were decreased(P<0.05).Dietary DL-Met or HMTBa supplementation increased taurine,methionine,leucine,tryptophan and arginine content,and decreased serine and lysine content in plasma(P<0.05).The redox status of laying ducks was improved by enhancing the glutathione peroxidase and catalase activities,glutathione content and its ratio relative to glutathione(oxidized)content and decreasing malondialdehyde content and increasing mRNA expression of superoxide dismutase-1,glutathione peroxidase-1,hemeoxygenase-1 and nuclear factor-like 2 in liver and ileum with the supplementation of DL-Met or HMTBa(P<0.05).Liver health status measured by average area proportion lipid droplet was improved with supplementation of DL-Met or HMTBa(P<0.05).Villus height and villus height to crypt depth ratio in the ileum and the ileal gene expression of tight junction protein and occludin were increased with DL-Met or HMTBa supplementation(P<0.05).Taken together,these results suggested that the efficacy of dietary supplementation of HMTBa was similar to DL-Met,and it ranged from 98%to 100%for productive performance and egg albumen ratio in laying ducks(25 to 41 wk).

Effects of dietary barley inclusion and glucanase supplementation on the production performance,egg quality and digestive functions in laying ducks

This study evaluated the effects of barley inclusion and glucanase supplementation on the productive performance and digestive function in laying ducks.The experiment used a randomized design with a 5×2 factorial arrangement of 5 graded levels of barley(0%,15%,30%,45%and 60%)with or without 1.5 g/kgβ-1,3-1,4-glucanase(15,000 U/kg).During the experimental period of 120 d,the weight and total number of eggs within each pen were recorded daily,and egg quality was determined every 4 wk.At the end of the experiment,3 randomly selected ducks within each replicate were sacrificed,then duodenal digesta and jejunal mucosa was collected.Dietary inclusion of barley had no effects on egg production,daily egg mass or FCR,but supplementation with glucanase improved egg production and FCR(P<0.01).Barley did not affect feed intake of laying ducks,but glucanase tended to increase feed intake(P=0.09).Neither barley norβ-glucanase had effects on the egg quality variables,except for yolk color score,which was decreased with increasing barley supplementation.Glucanase,but not barley,increased the activity of chymotrypsin and amylase in duodenal digesta.Barley inclusion affected the activity of alkaline phosphatase and maltase in jejunal mucosa(P<0.05),butβ-glucanase had no effects on the activity of these brush border enzymes.Barley inclusion increased the glucan content in duodenal digesta,but supplementation of glucanase to barley-based diet reduced digesta glucan content and reduced total volatile fatty acids and increased the proportion of acetic acid in cecal contents.The results indicate that,without glucanase,the optimal dietary barley level in the diets of laying ducks is about 13%for maximal production performance;glucanase supplementation of the barley diets improved production perfor-mance,probably through enhancing digestive function.