Research On Dietary Lysine And Methionine Requirements Of Muscovy Duck During Peak Laying Period

This experiment was conducted to investigate the effects of different levels of lysine and methionine in the diet on egg laying performance,reproductive performance,serum biochemical indexes,serum antioxidant and hormonal indexes of the duck breeders during peak laying period,as well as the effects of liver antioxidant indexes,m RNA expression of breast muscle development related genes and m RNA expression of yolk sac membrane and intestinal amino acid transporter in the middle and late stages of progeny embryo development.In order to explore the appropriate amount of lysine and methionine in the peak of laying eggs,it provides a certain reference for the actual production.Experiment 1: This experiment used a 4 × 4 two-factor design with four levels of lysine and methionine,methionine was set at four levels of 0.34%,0.43%,0.52%,and0.61%,and lysine was set at four levels of 0.75%,0.89%,1.03%,and 1.17%.A total of1728 healthy 30-week-old female muscovy ducks were randomly divided into 16 treatments,6 replicates per treatment,and 18 ducks per replicate.The experiment period was 6 weeks.At the end of the 6th week of the experiment period,the muscovy ducks were subjected to blood sampling under the wing vein,and the serum was separated and the eggs were collected for the last two days at the end of 6 weeks,in preparation for subsequent testing and incubation tests.Experiment 2:Experiment 2 is carried out on the basis of Experiment 1,and the experimental design of the culture and the grouping of animals are the same as Experiment1.Two Lys levels(0.89% and 1.17%)were selected for the hatchery experiment,and a single factor randomized experiment design was used.Met was set at four levels of 0.34%,0.43%,0.52%,and 0.61%.There were 4 treatment groups at 0.89% Lys level and 1.17%Lys level,with 6 replicates in each group and 12 eggs per replicate.The liver,breast muscle and yolk sack membrane were collected from embryonic embryos at 26 embryos.The liver,small intestine and yolk sack membrane were collected at 31 embryos.The liver antioxidant index and expression of genes related to the breast muscle,small intestine and yolk sack membrane were detected.The results showed that:(1)Different levels of Lys and Met in the diet had no significant effect on the average egg weight(P>0.05).When the dietary Met level was higher than 0.34%,the egg production rate and daily egg production were significantly increased and the feed to egg ratio was significantly decreased(P<0.05).High Lys level diet(1.17%)significantly reduced feed intake(P < 0.05).Different lysine and methionine levels had significant interaction effects on egg production rate,feed to egg ratio and qualified egg rate,and the performance of combining egg production with Lys: 0.89%,Met: 0.43% and Lys/Met: 2.07 was the best.(2)Different Lys and Met levels had significant effects on fertilization rate,dead embryo rate of 18 embryonic embryos,hatching rate and primary weight of ducklings(P<0.05).When the dietary Met level was higher than 0.43%,the weight of ducklings was significantly increased.When the Met level was 0.52%,the rate of healthy ducklings was significantly increased and the rate of dead embryos was significantly decreased(P<0.05).The Lys level significantly increased the hatching rate in the range of0.75%～0.89%.When the Lys level was 0.89%,the dead embryo rate of the eggs was significantly decreased(P<0.05).(3)Met had no significant effect on serum biochemical parameters(P>0.05).Lys had significant effects on serum total protein,serum urea nitrogen and alkaline phosphatase(P<0.05).With the increase of Lys level,alkaline phosphatase activity increased first and then decreased,and reached the maximum when Lys level was 1.03%(P<0.05).Serum total protein and serum urea nitrogen showed an opposite trend,and the Lys level dropped to the minimum when it was 1.03%(P<0.05).(4)Lys level had no significant effect on serum antioxidant index(P>0.05).When the Met level was 0.34%,the CAT activity was significantly increased(P<0.05).(5)Different levels of Lys and Met significantly affected the contents of LH,E2 and INS in the serum of muscovy ducks.(P<0.05).When the Met level was higher than 0.34%and the Lys level was higher than 0.75%,the contents of LH and E2 were significantly increased(P<0.05).(6)When the Lys level was 0.89% and 1.17%,the Met gradient had no significant effect on the liver antioxidant index of the embryos hatched to 26 embryos(P>0.05).(7)When the Lys level was 0.89%,the low Met level(0.34%)significantly decreased the activity of T-AOC and CAT in the embryonic liver of 31 embryos(P<0.05).CAT activity increased first and then decreased with the increase of Met level,and reached the highest when Met level was 0.52%.The Met level in the range of 0.43%～0.52%significantly decreased the MDA content of embryonic liver(P<0.05).When the Lys level was 1.17%,the Met gradient had no significant effect on the antioxidant indexes of 31 embryonic embryos(P>0.05).(8)When the Lys level was 0.89%,the Met level was 0.61%,which significantly up-regulated the expression of IGF-1 m RNA in the breast muscle of 26 embryos(P<0.05),and the low Met level(0.34%)significantly up-regulated the m RNA of Fox O4 and MAFbx.The expression of Fox O4 and MAFbx m RNA increased first and then increased with the increase of Met level,and the expression was lowest at 0.43% Met level.When the Lys level was 1.17%,the Met level had a significant effects on the relative expression of IGF-1and TOR genes(P<0.05).The relative expression of IGF-1 and TOR genes increased first and then decreased with the increase of Met level.The 0.52% Met level expressed the most.(9)When the level of Lys was 0.89%,the relative expression of CAT1,SLC6A19,SNAT2 and Taut m RNA in the yolk sac membrane of embryonic embryos at 26 embryos was not significantly different(P>0.05).When the Met level was less than 0.52%,the relative expression of r BAT gene was significantly inhibited(P<0.05).When the Lys level was 1.17%,the Met level had no significant effect on the relative expression of r BAT,CAT1,SLC6A19,SNAT2 and Taut m RNA(P>0.05).(10)When the Lys level was 0.89% and the Met level was 0.52%,the relative expression of CAT1,SLC6A19 and Taut m RNA in yolk sac membrane of 31 embryos embryonic was significantly up-regulated(P<0.05).When the Lys level was 1.17%,the relative expression of r BAT,SLC6A19 and Taut increased first and then decreased with the increase of Met level,the gene expression of 0.52% Met level was the largest(P<0.05),andthe relative expression of SNAT2 reached the maximum at 0.61% Met level(P<0.05);Met level had no significant effect on the relative expression of CAT1(P>0.05).(11)When the Lys level was 0.89% and 1.17%,the Met level had no significant effect on the relative expression of r BAT,CAT1,SLC6A19 and Taut m RNA in small intestine of31 embryos embryonic(P>0.05),and had a significant effect on the relative expression of SNAT2 m RNA(P<0.05),which showed that it increased first and then decreased with the increase of Met level,and the expression level of 0.52% Met was the highest.In summary,the appropriate requirements for the lysine and methionine diets of the muscovy ducks at the peak of laying eggs were 0.89% and 0.43%,respectively,and the ratio of lysine to methionine was 2.07.