The Effects Of Diets With Different Concentrate To Forage Ratios On Digestibility, Fermentation And Microorganisms Diversity In Yanbian Yellow Cattle

In this study, two experiments was conducted to evaluate the effects of diets with different concentrate to forage ratios on digestibility, ruminal fermentation and bacterial diversity in the early fattening Yanbian yellow cattle.Experiment1:The experiment was conducted to evaluate the effects of diets with different concentrate to forage ratios on digestibility and ruminal fermentation in Yanbian yellow cattle. Four Yanbian yellow cattle (initial BW300+15kg) were assigned to a replicated4×4Latin square design with4concentrate:forage ratios:very low (30:70), low (40:60), high (60:40), very high (70:30). The experiment was composed of4periods and each experimental period consisted of a15-d diet adaptation and5d of collection. The results shows that, intakes (kg/d) of DM,0M and CP linearly increased (P<0.01) with increasing the ratio of concentrate in diets, while that of NDF and ADF linearly decreased (P<0.01). The digestibilities of DM linearly increased (P<0.05) with increasing the ratio of concentrate in diets, that of CP linearly decreased (P<0.05). The digestibilities of0M and ADF had no significant different (P>0.05). The mean ruminal pH for64:40was lower than the other treatments (P<0.05), and the mean ruminal pH tended to linearly decreased (P=0.01). The NH3-N concentration for70:30was higher than the other treatments (P<0.05); ruminal VFA concentration was significant different (P<0.05). The concentration of acetic acid at6h was significant different (P<0.01). Acerate/propionate ratio and propionate concentrations was significant different at6h (P<0.05). The excretion (g/d) of total PD and allantoin linearly increased with increasing the ratio of concentrate in diets(P<0.05or P<0.01). Results indicated that increasing the ratio of concentrate in diets can not only increase the intakes (kg/d) of DM>0M and CP, but also decrease that of NDF and ADF in beef cattle. Additionally, the apparent digestibility of DM as well as the ruminal available nitrogen were increased with increasing the ratio of concentrate in diets.Experiment2:The experiment was conducted to evaluate the effects of diets with different concentrate to forage ratios on ruminal bacterial diversity in Yanbian yellow cattle. Three Yanbian yellow cattle (initial BW300±15kg) were assigned to a replicated3×4Latin square design with4concentrate:forage ratios:very low (30:70), low (40:60),high (60:40), very high (70:30). The experiment was composed of4periods and each experimental period consisted of a15-d diet adaptation and3d of collection. Collecting rumen fluid samples. Frozen-thaw treatment was used to extract rumen microorganisms’genome DNA. And then the16srDNA region was amplified by PCR. The PCR product was analyzed by DGGE (Denaturing gradient gel electrophoresis). DGGE profile was analyzed to compare the diversity and abundance of each groups. We use real-time PCR to compare the relative gene expression of each treatments. The results shows that, cluster analysis separated cattle fed the medium concentrate diets (4:6and6:4) from those fed high and low concentrate diets(7:3and3:7), with45%of the band positions being the same. The change of the concentrate to forage ratios substantially affects the microbial ecology of the rumen. But no difference in rumen bacterial communities between high concentrate diet (3:7) and low concentrate diet (7:3) was found. Band number decreased (P<0.05) in rumen samples taken from cattle fed diet (3:7) compared to those fed diets (4:6),(6:4) and (7:3). Shannon-Wiener index of3:7treatment was significantly different (P<0.05) compared with6:4and7:3treatment. That of6:4treatment was also significantly different (P<0.05) compared with7:3treatment. No significantly difference was found between diet (3:7) and diet (4:6)(P>0.05). The relative gene expression of B. fibrisolvens was significantly different (P<0.05). Compared with7:3treatment, the relative gene expression of B. fibrisolvens declined with a0.2,0.33,0.29-fold change respectively (P<0.05). While there was no difference in relative gene expression of total bacteria, Ruminobacter albus and Ruminococcus flavefaciens. The relative gene expression of methanogen mcr-a gene increased with a0.2,0.78,0.74-fold change respectively (P<0.05). Results indicated that the concentrate to forage ratios substantially changes the bacterial communities and diversity in rumen.