Study On Nutritive Value Evaluation And Practical Application For Poyang Lake Carex

Poyang lake is the biggest freshwater lake in China. The Poyang lake grass is a richfeed resource, mainly carex.To develop fully Poyang lake carex and beef cattle breeding,the study was conducted to evaluate nutritive value and practical application of Poyanglake carex. This paper was divided into four parts.The first part: study on palatability index of the straw and Poyang lake carexdetermination. After feed intake was determined through pre-feeding,6Jinjiang cattleswere randomly selected to feed straw and carex in hunger and satiation state, separately.The surplus grass ratio and palatability index were calculated by weighing the remainingstraw and carex after30minutes of ingestion. The results indicated the palatability indexof straw was significantly better than carex(P<0.01).The second part: study on rumen degradability of the Poyang lake carex.3healthymale jinjiang cattles of300±20kg,fitted with permanent rumen fistula, were used in thestudy. Degradation rate of dry matter DM, organic matter OM, crude protein CP, crude fatCF, neutral detergent fiber NDFand acid detergent fiber ADF were determined after4,8,16,24,36,48and72h in rumens of the cattles by nylon bag method. The rumendegradation parameters were calculated and compared with those of alfalfa and pennisetumhydridum.The results indicated the carex contains higher nutrition and the degradable partof cude protein was68.9%(alfalfa86.28%and silage pennisetum hydridum49.63%),suggesting the protein quality of carex was better than the silage pennisetumhydridum but lower than alfalfa. Carex’s degradable part of DM, OM were also higherthan silage pennisetum hydridum, but lower than alfalfa. Carex’s NDF, ADF degradablepart were lower than alfalfa and silage pennisetum hydridum. The results indicatednutritional value of carex was higher than pennisetum hydridum but lower than alfalfa.The third part: study on effects of the different NFC/NDF in carex-based diets onrumen fermentation of the cattles in vitro. Three treatments of NFC/NDF ration of0.42,0.52and0.59were designed in the study,five replicates each treatment. The indexesof rumen fermentation were measured by in vitro gas production techniques after24hours. The results indicated that:(1) gas production was increased with the improvementof the NFC/NDF ration but difference between each group was not significant(P>0.05); pHwas extremely significantly declined(P<0.01) and NH3-N was extremely significantlyincreased(P<0.01)with the improvement of the NFC/NDF ration in each group;(2) theconcentration of BCP was increased with the improvement of the NFC/NDF ration and the values of0.51and0.59group were significantly higher than the group of0.42(P<0.05);(3)the total VFA concentration was increased with the improvement of the NFC/NDF rationand the values of0.59group was significantly higher than the group of0.51and0.42(P<0.05);(4)the propionic acid concentration was extremely significantly increasedwith the increase of NFC/NDF in3groups(P<0.01);propionic acid and butyrateconcentration was not significant among3groups(P>0.05);the acetic acid/propionic acidwas decreased extremely significantly with increase of NFC/NDF(P<0.01)(5)BCP andVFA concentration were positively correlated with NFC/NDF and the regression equationwas:y=0.3605x-0.32(y was BCP concentration and x was NFC/NDF,R2=0.7982);y=0.013x-0.4652(Y was BCP concentration and x was VFA concentration,R2=0.9218),respectively.The fourth part: Determination of optimal proportion of straw and carex. Carex andstraw were mixed by the ratio of0：100（A)、20：80(B)、40：60(C)、60：40(D)、80：20(E)and100：0(F)， respectively， with6replicates in each group.Gas production、pH、ammonia nitrogen、 BCP and VFA were determined by batch culture methods in vitroafter24hours. The results indicated that:(1) the gas production in each group was notsignificantly different(P>0.05)；(2) pH of each group were in the normal range, with lowervalue in A、B and F group, higher in E group and optimal in C、D;(3) D group had themost production of BCP, significantly more than A、B、E、F group(P<0.05),but not than Cgroup(P>0.05);(4) NH3-N production in D group was highest and that in F group waslowest;(5) in C group was highestand was significantly more than A、 B、 E andF(P<0.05)but not than D group(P>0.05).the lowest VFA production was A group and thesecond was F;(6) the ratio of acetate/propionate in C group was lowest and significantlyless than A、B and F group(P<0.05)but not significantly lower than D and E group(P>0.05).The ratio of F group was the highest and A group was the second. Comprehensively,the Cand D was the best two groups and it was advised that the proportion of the mixture ofstraw and carex were set form40:60to60:40.