Effects Of Dietary Forage To Concentrate Ratio On Rumen Epithelial Barrier Function In Dairy Cow And Goat

In this study, three experiments are included:1. Effect of different forage to concentrate ratio dietary on cows rumen epithelial barrier function.2. Effect of forage to concentrate ratio dietary on goat rumen epithelial barrier function.3. Effect of pH and SCFA on mRNA abundance of cell junction protein in rumen epithelial.1. Effect of different forage to concentrate ratio dietary on cow rumen epithelial barrier functionExperiment1:Four ruminally cannulated Holstein dairy cows in their first lactation were used for this study. The cows were assigned to two dietary treatments. In the first group the cow get a high forage to concentrate ratio (7:3, HC) dietary and in the second group get a low forage to concentrate ratio (6:4, HF) dietary. Using a2x2repeated crossover design. Cows were fed in2equal portions at08:00and18:00h daily, and had free access to water. Every group was taken samples after21days feeding. Rumen epithelial barrier structural changes were studied between the two groups. It was found that in the high forage to concentrate ratio group the concentration of propionate, acetate and butyrate of rumen fluid were high, and pH was low; By using scanning electron microscope, hyperkeratosis phenomenon was found in stratum corneum; Using optical microscope, the intercellular space of the rumen epithelium was became big; Using transmission electron microscope, it was found that tight junction, desmosome junction and hemidesmosome junction were decreased and not clearly. Using real time qPCR method, it was found that the claudin-1, claudin-4, occludin, ZO-1, connxin43and DSG1mRNA expression level of rumen epithelial were tend to decreased, and the expression level of ZO-1mRNA was significantly decreased (P<0.05).Experiment2:Eleven ruminally cannulated Holstein dairy cows were used for this study. Accordance with the dietary component the cows were separated to mixed forage (MF) group (n=6) and com straw (CS) group (n=5). Nitrogen and energy in the dietary of the two group were same. Feeding mode, experiment period and detection indicators were the same with experiment one. Test results were consistented to experiment one. But, the forage to concentrate ratio in the two group is different. The forage to concentrate ratio in mixed forage (MF) group was4:6, and in mixed forage (MF) group was6:4. Cows were fed in2equal portions and had free access to water. The results showed in this experiment were consistent with experiment1.The results of the two experiment were that rumen epithelium barrier structures were damaged when the cows feed a high forage to concentrate ratio dietary.2. Effect of forage to concentrate ratio dietary on goat rumen epithelial barrier functionThirteen ruminally cannulated goats were used for this study. The goats were separated to high forage to concentrate ratio dietary (HC,6:4) group and low forage to concentrate ratio dietary (HF,4:6) group. Goats were fed in2equal portions at08:00and18:00h daily, and had free access to water. Every group were taken samples after21days feeding. Rumen epithelial barrier structural changes were studied between the two groups. It was found that in the high forage to concentrate ratio group the concentration of propionate, acetate and butyrate of rumen fluid were high, and pH were low; Hyperkeratosis phenomenon was found in stratum corneum; The intercellular space of the rumen epithelium was became small; Tight junction, desmosome junction and hemidesmosome junction were increased and more clear. Using real time qPCR method, it was found that the claudin-1, claudin-4and ZO-1mRNA expression level of rumen epithelial were significantly increased (P<0.05). Occludin and connxin43mRNA expression level tend to increased, and the expression level of DSG1mRNA was significantly decreased (P<0.05).The results of the goat experiment were that rumen epithelium barrier structures were Strengthened when the goats feed a high forage to concentrate ratio dietary, and this was contrasted with cow’s experiment.3. Effect of pH and SCFA on mRNA abundance of cell junction protein in rumen epithelialThe attached cells were treated by low pH and high SCFA. It was found that claudin-4and occludin mRNA expression level were mainly influenced by pH. ZO-1and DSG1mRNA expression level were mainly influenced by SCFA. Claudin-1and connxin43mRNA expression level were influenced by pH and SCFA.