| Based on forage grading index ( GI) and the optimum ration design putting forward by Prof.Dexun-Lu in 2002 ,the experiments were conducted (1) to determine GI ,and to evaluate the associative effects existed between different forages or between concentrate and forage; (2) to design and select the optimum mixed forage formulation by GI, and then a appropriate concentrate matching with the forage mixture in terms with the maximum of multiple-factors associative effects index (MFAEI) , both In Vitro and In Vivo.And a comparative study between the selected ration formula and medium quality hays supplemented with the selected concentrate (F:C,7:3 ) was made to determine the responses of animal performance and nitrogen retention.Exp 1. The determination of GI to four foragesThe ME of the four forages were determined by Tilley and Terry ( 1963) technique.Sixteen healthy Inner Mongolian semi-fine wool sheep weighting 20-25Kg were divided into 4 groups randomly and given the four forage respectively for voluntary intake determination .Through the calculation of the two experiments' data , the GI of the four forages was obtained.They are Astrgalus adsurgens (legume )( AA) :36.99(MJ);Zeym? chinensis (Trin. )Tzvel. (Gramineae ) ( LC ) :15.90(MJ);Corn straw ( CS ) :7.22(MJ);Rice straw (RS) :3.98(MJ). And the quality order of the four forages evaluated by GI is Astrgalus adsurgens > Leymus chinensis (Trin. ) Tzvel > Corn straw > Rice straw.Exp 2. The study of the associative effects among the feedstuffsBased on in vitro batch incubation, The associative effects existed between different forages or between forage and a concentrate (C) were studied. We observed the significantly positive associative effects when the each four forages incubated mixed the same concentrate in the In Vitro trail (F:C is 7:3) . Especially the LC,which MFAEI (1.11) is the highest;the next is the AA ,MFAEI is 0.76 and CS is 0.71 ;The last is the RS,which MFAEI is 0.43. The positive associative effects also found when the different forage mixtures mixed with thesame concentrate in comparison with the single forage supplemented with the same concentrate .When the LC> CS and RS substituted the AA as 50% respectively ,the positive associative effects occurred compared with AA as 100%.Especially (CS+AA)+C as (35:35:30) (CH) has the biggest MFAEI (0.51);(RS+AA)+C (35:35:30) (RH) MFAEI was the next(0.37) and MFAEI of (LC+AA)+C (LH) was 0.24. These mixtures also appeared significantly positive associative compared with LCU CS and RS as 100%,respectively.The MFAEI of RH> LH and CH is 1.00> 0.72 and 0.70.Exp 3. The selection of the optimum mixed forage fomulationBased on in vitro batch incubation, the selection of the optimum mixed forage formulations was made.The results of the experiment showed that there was significantly correlationship between GI(M.T) (X) and it's IVDOM (%) (Y) . The regression equation obtained were showed as follows:Y=0.815X+15.392 (R2=0.6785,P < 0.0001,n=18) .According to GI, the feed cost and the In Vitro degradation indexes of the mixed forage formula comprehensively , one optimum formula was selected out .They were LC:CS:AA (10:50:40) , with GI 20.00 (MJ) and cost of 0.63 /kg.Exp 4. The design and selection of the most appropriate concentrate formula matched with the optimum forage mixtureBased on the results obtained from the Exp 3, a further selection of a proper concentrate for the mixed forage formula by In Vitro was carried out.Keeping the SC/NSC as 1.17, the proportion of UDP/RDP in the range of 0.49-0.80 was regulated. The second formula was chosen ( UDP/RDP:0.60) as the most appropriate concentrate formula according to the maximum of the MFAEI (0.64).Exp 5. The comparative study of animal performance and nitrogen retention between the selected ration formula and the medium quality hayBased on the results of Exp3 and 4,eight healthy Inner Mongolian semi-fine wool sheep weighting 40.91+1.13Kg were divided into 2 groups randomly and given the optimum selected formulation and medium qual... |
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