| This study was conducted to investigate the effects of coated folic acid(CFA)and coated methionine(CM)supplementation and their interactions on growth performance,nutrient digestion and metabolism,rumen fermentation,and blood indicators of finishing Doper × Thin-tailed Han F2 crossbred male lambs in the summer.Forty Doper × Thin-tailed Han F2 crossbred male lambs with similar body weight(30.08 ±1.34 kg)and good condition were arranged into four groups in a randomized design with a 2 × 2 factorial arrangement.One factor was supplemented CFA(0 mg,CFA-or 4 mg·(kg·d)-1,CFA+)in the diet according to the body weight of the experimental animals,and the other factor was supplemented CM(0 g,CM-or0.1 g·(kg·d)-1,CM+).The feeding experiment included 15 d of adaptation and followed by 70 d of trial period.The results showed that:(1)There were significant effects of CM supplementation on average daily weight gain during 1~30 d and 1 ~ 60 d and feed conversion ratio(P < 0.05).Average daily weight gain,feed conversion ratio,and the apparent digestibility of dry matter,organic matter,neutral detergent fiber and acid detergent fiber were significantly improved with CFA supplementation in the ration of finishing lambs(P < 0.05).CFA group and CM group decreased urinary energy,urinary nitrogen,fecal nitrogen and total excretion nitrogen(P < 0.05),enhanced energy digestibility and metabolizable ratio,apparent digestibility of nitrogen and the deposited nitrogen(P < 0.05).(2)The addition of CFA or CM reduced ruminal average NH3-N,molar ratio of isovaleric acid and malonaldehyde(MDA)(P < 0.05),enhanced ruminal total volatile fatty acids(TVFA),enzyme activity of cellobiase,α-amylase,xylanase and protease,and activities of CAT,T-SOD and GSH-PX in the rumen fluid(P < 0.05).(3)The addition of CM increased the concentration of serum heat shock protein 90,heat shock protein 70,TNF-α in serum at 60 d,enhanced serum albumin,methionine and Hcy at 30 d and 60 d(P < 0.05),reduced serum BUN and folic acid concentration at 30 d,and 5-methyltetrahydrofolic acid at 60 d(P < 0.05).The addition of CFA increased serum glucose at 30 d,serum 5-methyltetrahydrofolate and folic acid at 30 d and 60 d(P < 0.05),the serum BUN,TNF-α,interleukin-6 and interleukin-2 at 60 d,reduced the serum homocysteine in serum at 30 d and60 d(P < 0.05).The addition of CFA or CM increased the activities of T-SOD,CAT and GSH-PX in serum at 30 d and 60 d(P < 0.05),reduced the concentrations of serum MDA at 30 d and 60 d(P < 0.05).(4)The CFA × CM interaction had a significant effect on feed conversion ratio during 1~60 d,nitrogen excretion,nitrogen digestibility,number of total bacteria and R.albus,ruminal MDA,GSH-Px at 30 d during the experimentation,and glucose,ALB,T-SOD,TNF-α and CAT at 30 d and 60 d during the test(P < 0.05).In conclusion,Adding CM or CFA to the diet increases the number of bacteria and the corresponding enzyme activity,improves nutrient digestion and metabolism,and the body’s antioxidant capacity,thereby promoting the growth of Doper × Thin-tailed Han F2 crossbred male lambs.The addition of the two has positive obvious interaction effects on the number of total bacteria and ruminococcus.albus,the apparent digestibility of nitrogen and the conversion rate of diet. |
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