胍基乙酸和甜菜碱对羔羊生长性能、瘤胃发酵和血液代谢的影响

【目的】研究饲粮中添加胍基乙酸和甜菜碱对羔羊生长性能、瘤胃发酵及血清生化指标的影响，为胍基乙酸和甜菜碱在反刍动物生产中的应用提供理论依据。【方法】试验选用48只体重相近(22.03±1.30)kg、3月龄左右的杜泊×小尾寒羊杂种公羔，采用2×2因子完全随机试验设计，试验因素为胍基乙酸(guanidineacetic acid,GAA)(0或900 mg·kg^-1)和甜菜碱(betaine,BT)(0或5 g·d^-1)。试验羔羊随机分为4组，每组12只。分别为对照组、GAA组、BT组和GAA+BT组。试验期共75 d，其中预试期15 d，正试期60 d。正试期第1天晨饲前称量体重作为初始体重(IBW)，正试期内记录每只羊的日采食量、剩料量；正试期结束当日晨饲前先采血后空腹称重，作为终末体重(finwal body eight,FBW)，计算平均日增重(ADG)、平均日采食量(ADFI)和饲料效率(FE)；血清用于肌酸代谢指标、同型半胱氨酸(Hcy)和乳酸含量测定。试验结束当天正常饲喂试验羊，3h后采集瘤胃液，测定瘤胃发酵参数、消化酶活性以及功能...

Effects of Guanidinoacetic Acid and Betaine Supplementation on Growth Performance,Rumen Fermentation and Blood Metabolites in Lambs

【Objective】This study was conducted to investigate the effects of dietary guanidinoacetic acid (GAA) and betaine (BT) on growth performance, rumen fermentation and blood metabolites in lambs, so as to provide a support for applying GAA and BT on ruminants. 【Method】Forty-eight 3-month-old Dorper×Thin-tailed Han F₁ hybrid male lambs with similar body weight (22.03±1.3 kg; mean±SD) were randomly divided into 4 groups with a 2×2 factorial arrangement, and the experimental factors were GAA (0 or 900 mg/kg) and BT (0 or 5 g/day). Lambs in four groups were control group, GAA group, BT group and GAA+BT group, respectively. The feeding experiment lasted for 75 days with 15 days of adaptation. On the first day of the formal experiment period, the body weight (BW) before morning feeding was weighed as the initial BW, and each lamb were recorded accurately the amount of feed and residual of weight every day; at the end of the trial period, the blood samples were collected from the jugular vein, and final body weight (FBW) was weighed before morning feeding to calculate average daily gain (ADG), average daily feed intake (ADFI) and feed efficiency (FE). The blood serum was used for the determination of creatine metabolism indexes, homocysteine and lactate content. The rumen fluid was collected from all lambs at 3 hours after feeding at the end of the experiment, which were used to measured rumen fermentation parameters, digestive enzyme activity, and functional microorganisms. 【Result】(1) Compared to the control group, the addition of GAA in the diet did not significantly increase ADG (P>0.05), while the addition of BT increased ADG significantly (P<0.05). The addition of GAA or BT in the diet increased FE significantly (P<0.05), and GAA and BT had significant interaction on ADG and FE (P<0.05). (2) The rumen pH was decreased by addition of GAA or BT (P<0.05), and the concentration of propionic acid and total volatile fatty acid were increased by GAA or BT (P<0.05). There was no significant interaction between GAA and BT on rumen fermentation in lambs (P>0.05). (3) The addition of GAA or BT increased the populations of R. flavefaciens, F. succinogenes, B. fibrisolvens, and P. ruminicola (P<0.05), and decreased the populations of total protozoa (P<0.05). The addition of BT decreased the populations of total methanogens and had a tendency to increase the populations of Rb.Amylophilus (P<0.05, P=0.098). GAA had a tendency to decrease the populations of total methanogens (P=0.088). The addition of GAA and BT had no significant interaction effect on ruminal main functional microflora in lambs (P>0.05). (4) The activity of protease was increased by addition of GAA and BT (P<0.05). The addition of BT increased carboxymethyl-cellulase, xylanase and α-amylase activities (P<0.05), and had a tendency to increase cellobiase activity (P=0.075). GAA increased pectase activity (P<0.05), and had a tendency to increase α-amylase activitiy (P=0.056). The significant interaction effect between GAA and BT was observed on pectase (P<0.05). (5) The addition of GAA or BT increased the content of creatine in blood serum (P<0.05). The addition of GAA had a tendency to increase the concentration of homocysteine (Hcy) and to decrease L-arginine-glycine amidinotransferase (AGAT) (P=0.053, P=0.056). BT decreased the content of Hcy in blood serum, and had a tendency to increase creatine kinase (P=0.063). GAA and BT had no interactive significant effects on blood metabolites (P>0.05). 【Conclusion】In conclusion, the addition of GAA or BT promoted rumen fermentation, increased the populations of functional rumen microflora and microbial enzyme activity, elevated serum creatine levels, and decreased the content of homocysteine. However, the combination addition of GAA and BT did not further increase the performance of lambs when compared with the addition of GAA or BT alone.