Rumen and Fecal Microbiota of Dairy Cows. Bos taurus breed:Holstein Friesian

This experiment functioned to predict the production of CH4 based on the relative abundance of bacterial biomarkers in the fecal environment. Six mature non-lactating Holstein dairy cows were offered one of three diets with forage to grain ratios of 100:0 (G0), 75:25 (G25), and 50:50 (G50). The forage portion of the diet consisted of 80% grass hay and 20% alfalfa hay (DM basis). The concentrate was a barley-corn based ration (DM=893 g/kg, CP=198 g/kg DM). Feed was offered three times daily at 0900, 1300, and 1700. The experiment was a replicated 3x3 Latin Square Design, with each animal receiving each of the three diets over the course of the three 5-week periods. Experimental diets were switched during the first week of every period. This was followed by three weeks dietary adaptation. Sample collection and enteric methane output measurement via an open-hood calorimetric system were conducted on two separate days during the fifth week of every period. Rumen fluid was collected using a stomach tube and a fecal grab samples were taken to determine pH at 0830 and 1500 on the day preceding enteric methane output. The identity and composition of bacteria present in the sample was then determined using 16S rRNA sequencing.