Influences Of Different Sorts Of Roughages And Addition Of Buffer On Ruminal Fermentation In Sheep

This research work content two parts of experiments.4 ruminally cannulated sheep(weighed about 26kg ) were used as trial animal in a 4×4 Latin square design to study the effects of 4 sorts of roughages(alfalfa,maize stover,maize silage,leymus chinensis) on rumen fermentation in sheep. the measured parameters mainly content pH,buffer capacity,concentration of NH3-N,concentration of VFA and ruminal liquid dilution rate. Each period of every experiment included 15 days for adaption,and 4 days for sample collecting. The results of experiment 1 showed that 4 sorts of roughages affect ruminal pH significantly at the same time points(p<0.05).The biggest varying range of pH(0.81) during 8 hours after feeding as well as average pH appeared in sheep fed on alfalfa,and the smallest varying range(0.5) and average pH appeared in sheep fed on maize stover. sheep fed on maize stover got the biggest ruminal liquid buffer capacity(p<0.05)compared with others,and the differences between alfalfa,maize silage,leymus chinensis were not significant(p>0.05).The concentration of NH3-N were not significantly affected by sorts of roughages,though sheep fed on alfalfa reached the highest NH3-N concentration,and maize stover group was of the lowest level. The varying trend of VFA were roughly the same among sheep fed on different sorts of roughages, except that the concentration of acetic acid at 2 hours after feeding was significantly(p<0.05)higher in sheep fed on alfalfa. And the ratio of acet/prop were not significantly affected by sorts of roughages. These had little effect on ruminal liquid dilution rate, either.In experiment 2,addition of buffer significantly increased pH at almost every time point compared with the control diet(p<0.05),except at 0 hour point,the average amount of pH increase was 0.2,and the difference between two trial diet was not significant(p>0.05). And as the addition of buffer increased,buffer capacity of ruminal liquid increased as well,but it was not affected by the amount of buffer in a linear pattern. Two trial diets increased BC significantly,but the difference in between was not significant(p>0.05). The concentration of NH3-N were relatively higher in sheep fed on control diet,but the difference was insignificant,the two trial diets had similar NH3-N concentrations. Addition of buffer decreased the concentrations of VFA at almost every time point,but the difference were insignificant(p>0.05). except when it comes to the concentration of acetic acid and TVFA at 4 hour after feeding. Acet/prop varied in the range of 2 to 3,addition of buffer slightly increased the rate of acetic acid,but it was not significant. the effect of the trialⅠand trial Ⅱ were almost the same. Addition of buffer had the trend of increasing LDR,and the difference between trialⅡand control was significant,while others were not. Conclusions can be drew as follows: 1)when sheep was fed with high rate of concentrate,maize stover can ensure high level of ruminal BC,and relatively normal pH,so it is not necessary to add buffer in diet; When feed on alfalfa,ruminal BC is relative low,pH can be very low,so adding buffer is necessary; leymus chinensis and maize silage bring medium pH,maybe a little lower than normal level,so it is recommended to add certain dose of buffer.2)Maize stover,maize silage and leymus chinensis has little effect on NH3-N or VFA,alfalfa may affect ruminal fermentation at certain level,maybe because of its relative high level of CP .3)Addition of buffer can effectively affect ruminal fermentation on pH and BC and LDR,but its effect on NH3-N and VFA is not as significant,at least at this in vivo experimental level.