Effects Of Different Concentrate Ratio On Digestion Digestibility And Fatty Acid Metabolism Of Rumen And Liver In Dairy Goats

The aim of this project is to research on effects of different concentrate ratio on nutrient digestibility and fatty acid metabolism of rumen and liver in dairy goats. Six mid-lactating Xinong Saanen dairy goats with catheters placed in portal, hepatic vein and femoral artery were used as animal models to determine the apparent digestibility and fatty acid in rumen, PDV tissue and liver in dairy goats. The experiment will be divided into three parts:Experiment1Study on the effect of different concentrate ratio on digestion metabolism in dairy goats. Six mid-lactating Xinong Saanen dairy goats (average weight60-65kg) were housed indoors in individual metabolic pen, used in a randomized crossover trial design,2periods, lasted18d each period. Goats were fed high concentrate diets (40%hay and60%concentrate, HC) or high forage diets (60%hay and40%concentrate, HR). The results show that, the concentrate and dry matter intake of HC diets were higher than HR diets and were increased by79.34%and21.32%, but the differences were not significant (P>0.05). The ADF, NDF, EE apparent digestibility of HC diets were higher than HR diets and were increased by8.85%、14.67%、3.79%, but the apparent digestibility of CP, Ash were decreased, and Ash reached a significant difference level (P<0.05). Increasing dietary concentrate quantity is helpful to improve the apparent digestibility of P, and the apparent digestibility of Ca which was fed the HC diets was decreased significantly (P<0.05). Dairy goats fed different diets, milk fat percentage, milk protein percentage and non fat solids were different, they were decreased by14.89%、20.87%、1.88%in dairy goats fed HC diets than HR diets. The lactose rate was increased by5.93%(P<0.01) in dairy goats fed HC diets than HR diets.Experiment2The aim of this experiment was to evaluate the effects of different concentrate ratio on pH value and VFA contentraion of rumen fluid. Six mid-lactating Xinong Saanen dairy goats with ruminally cannula, were housed indoors in individual metabolic pen, used in a randomized crossover trial design,2periods, lasted18d each period. Goats were fed high concentrate diets (40%hay and60%concentrate, HC) or high forage diets (60%hay and40%concentrate, HR), the diet was fed twice daily, and water was available ad libitum. The rumen fluid were obtained simultaneously from the rumen at0hr (before feeding), and at2,4,6and8hr (after feeding) at last day of each period. The result showed that the average pH value of rumen fluid was decreased in HC compared with HR diets (P<0.05). The pH value decreased to minimum at2h post-feeding, and the minimum pH values were6.01and6.69, respectively, which reached significantly level (P<0.05) between HC diet and HR diet, then gradually increased and returned to the pre-feeding level. The maximum rumen pH between the two groups had no significant difference (P>0.05). The concentrations of acetic, isobutyric acid, butyric acid, isovaleric, valeric acid, branched VFA and TVFA of rumen fluid were higher in HC than in HR diet and increased2.78%,17.20%,63.65%,48.18%,48.42%,34.44%,7.15%, respectively, and butyric acid concentrations reached a significant difference level (P<0.05). The concentrations of propionate was decreased by17.29%(P<0.01) in goats fed HC diets compared with HR diets.Experiment3This experiment was to study on the effect of different concentrate ratio on VFA and fatty acid metabolism in the liver of dairy goat. Six mid-lactating Xinong Saanen dairy goats with catheters placed in portal vein, a branch of the hepatic and femoral artery, were housed indoors in individual metabolic pen, used in a randomized crossover trial design,2periods, lasted21d each period. Goats were fed high concentrate diets (40%hay and60%concentrate, HC) or high forage diets (60%hay and40%concentrate, HR).The diet was fed twice daily, and water was available ad libitum. The blood samples were obtained simultaneously from the portal, hepatic and arterial catheters at0hr (before feeding), and at2,4,6and8hr (after feeding) at last day of each period.The results show that the concentrations of acetate, butyrate, TVFA, and the ratio of acetate to propionate were markedly higher (P<0.05), while the concentrations of propionate was lower (P<0.05) in the portal, hepatic vein and artery in dairy goats fed HC diets than HR diets, except acetate concentration in the portal and hepatic vein. Acetate, butyrate, and TVFA concentration were increased by2.20%,162.5%and2.90%in portal,4.50%,83.33%and2.57%in hepatic vein, and7.36%,66.67%and6.82%in artery, respectively, when goats were fed HC diets compared with HR diets. There were no effects (P>0.05) in interaction between diet and time. The concentrations of MUCF and PUFA were higher (P<0.05) in the portal, hepatic vein and artery in dairy goats fed HC diets than HR diets, while concentrations of SFA were lower than HR group.