Effects Of Rumen-protected Methionine Supplementation On Performance And The Expression Of IGF-1mRNA Of Mutton Sheep

The study selected hornless Dorset and Thin-Tailed Han crossbred F2which fixedathwart cross. The effects rumen-protected methionine supplementation on growthperformance, digestibility of nutrients and the expression of IGF-1mRNA were studied bythe feeding test, digestion-metabolism experiment and real-time fluorescent quantitativePCR. A total of56healthy sheep, aged4months and25±1.09kg average BW, wererandomly allocated to four groups and fed with different levels of rumen-protectedmethionine (0g/head/day,3g/head/day,6g/head/day,9g/head/day). The experimentconsisted of20-day preliminary period and56-day experimental period. Sheep in alltreatments were weighed individually every15days during the whole experimental period.On day45of the finishing period, three animals from each treatment group were randomlychosen and housed individually in metabolism crates to evaluate nutrient digestibilities.3-day preliminary period and4-day experimental period. Collection full excrementsanalysis method was used in this experiment, every sheep’s excrements and feed wereweighted every day. The sheep’s liver were sampled after feeding trials. The contents ofcrude protein, crude fat, Ca, P and dry matter in excrement samples and feed samples weremeasured by conventional method, the contents of neutral detergent fiber and aciddetergent fiberwere surveyed by filter-bag technology.The results showed that in terms of overall,3g/head/day group was the best on weightgain, it’s higher than0g/head/day group8.16%;6g/head/day group’s males was the best ofall the male sheep on weight gain, it’s higher than0g/head/day group10.10%;3g/head/day group’s females was the best of all the female sheep on weight gain, it’shigher than0g/head/day group13.4%, but it was non-significant(P＞0.05) between groups.Digestibility of dry matte, crude protein, crude fat, Ca and P had not been effected byrumen-protected methionine supplementation. Digestibility of neutral detergent fiber andacid detergent fiber had a slight trend of improvement, but it’s also not significant(P＞0.05). The expression of IGF-1mRNA had no significantly(P＞0.05) between groups. Itindicated that the expression of IGF-1mRNA was unaffected by rumen-protectedmethionine supplementation. The composition of feed, the level of protein and the consistof amino acid may influence the result of methionine supplementation, adding or notshould be considered based on feeds in production.