Effects Of N-hydroxymethyl-DL-methionine-Ca(N-HMM-Ca) On Ruminal Fermentation And Nutrient Digestion And Metabolism In Sheep

In a 3X3 Latin square design trial, 3 Tan-yang Sheep equipped with ruminal and T-typeduodenal cannulas were given a basal diet (40% concentrate, 60% roughage) without (control)or with rumen addition of 3g DL-methionine or 4.67g N-HMM-Ca(equivalent to 3gDL-methionine) to study the effect of N-hydroxymethyl-DL-methionine-C (N-HMM-Ca )onrumen enviroment,digestion metabolism of diet nutrients,microbia1 protein synthesis and b1oodplasma parameters .The results showed that ammonia N concentrarion in the rumen fluid wasdecreased when N-HMM-Ca or Met were added directly into rumen,moreover,average ruminalammonia N concentration was lower with addition of N-HMM-Ca than that with Met andcontrol.A1though pH va1ue and total VFA concentration in the rumen fluid were not affected byN-HMM-Ca addition and Met addition,Ruminal acetic acid and butyric acid concentrations tendedto eIevate,compared with controI.Adding N-HMM-Ca or Met increased total digestibilites of DM.OM. CP. ADF and NDF in sheep,with no significant difference betWeen N-HMM-Ca addition andMet addition. Duodenal NAN flow was highef, and Duodenal ammonia N flow was lower,Withaddition of N-HMM-Ca than Met and Control. When N- HMM-Ca was added into the rumen, flowof microbial N into duodenum was increased by 28.56%(p<0.05) and ll.0l%(p>0.05)respectively,compared with control and Met addition.N retention in sheep for N- HMM-Catreatment was 37.95% and 76.57% greater than that for Met treatment and controlrespectively,,mainly due to decreased urinary N. blood plasma methionine concentration washigher with addition of N-HMM-Ca was higher than that with control (p<0.01)and that with Metaddition(p<0.l0).Compared with Met treatment and control,blood plasma SAA(Met+Cys),.a1bumin and total protein tended to increase,and PUN tended to decrease by N-HMM-Caaddition.No significant change was fOund in plasma NEFA concentration.It can be concluded that a -'fraction N-HMM-Ca survives rumen microbial degradation to provide a rumen-protected form ofmethionine,at the same time that it enchanced ruminal fermentation and improved microbialprotein synthesis.