Study On Modelling Of Forage Grading Index Paramaters And Associative Effects In Mixed Forages

This paper mainly studied on modeling of forage grading index( GI) parameters and associative effects in mixed forages with combination techniques of In Vitro and In Vivo. Twelve healthy Inner Mongolian semi-fine wool sheep weighting 40.91(±1.13)㎏ wethers were divided into four groups randomly thrice and fed the these sheep with the twelve forages respectively for voluntary intake determination . The ME of the four forages were determined by Tilley and Terry(1963)technique. The models of GI parameters proposed by Dr. LU De-xun were established: The predicting models for dry matter intakes(DMI)and metabolizable energy (ME)of common sheep forages. Especially the models of predicting DMI with unNDFF(undigestivable NDF by feces inocula techniques ) as precdicter were established. The models with unNDFF were nearly equal to those of with unNDFR (undigestivable NDF by feces inocula techniques). Both unNDF as DMI predicting model factors were better then NDF. Considering the activity of rumen inocula is affected by the diet of the donor, especially disadvantage of need for fistulated donor ruminants to provide the liquor, incubation technique is suggested as a better technique for this this purpose. Eight healthy wethers(about 41㎏) of Inner Mongolian semi-fine wool sheep, fitted with permanent cannulas in the rumen and at the proximal duodenum and terminal ileum were used twice successively to investigate the flow rate and digestibility of different GI values of mixed forages with different forages/concentrate ratios in the whole digestive tract. Firstly, According to principles of maximum multiple-factors associative effects indices(MFAEI)of IVOMD,MCP and TVFAs In Vitro, and the change of ruminal pH values, H9:1,H8:2,L9:1 and L7:3 were chosen from six mixed rations with different GI values of mixed forages and different forages/concentrate ratios. Secondly, based on determination of pH values,NH3-N,VFAs and MCP in rumen liquid of experiment sheep fed with H9:1,H8:2,L9:1 and L7:3 respectively, the DM flow rates and DM and NDF digestibility of H9:1,H8:2,L9:1 and L7:3 in different segments of the digestive tract were determined. Thirdly, The animal performances for the sheep and nitrogen retention,blood glucose,PUN were determined too. The objective of all these studies was for GI technique extension and optimizing formulation of ruminant ration. The more nitrogen retention, the less PUN., and more daily gains. The feed/gain ratios for 4 mixed rations were 17.17-21.47, the sequence from high to low was L9:1(21.47)﹥L7:3(19.86)﹥H8:2(18.86)﹥H 9:1(17.17), the figures in parentheses are feed/gain ratios, there were greatly significant differences among these 4 mixed rations(P﹤0.01). H 9:1 could reduced feed/gain ratio. This indicated that high GI rations could get good feed/gain ratio when concentrates were very little, but for low GI rations could do that only when concentrates were very high and cause environments pollution for too much nitrogen excretion.