Abstract
The objective was to understand the effects of diet and age on the rumen bacterial community and function, 48 dairy cattle were selected. Rumen fluid samples were collected from each animal at 1.5 (1.5M, milk and starter diet, n=8), 6 (6M, starter and oat grass, n=8), 9 (9M, high fiber diet, n=8), 18 (18M, high fiber diet, n=8), 23 (23M, high fiber diet, n=8) and 27 (27M, high grain diet, n=8) months old. The acetate/propionate ratio (A/P) at M9, M18, and M23 were significantly higher than M27 and M1.5 (P < 0.05), while the A/P at M6 was lower than others (P < 0.05). The total volatile fatty acid at M23 and M27 was higher than others (P < 0.05). The urease at M18 was significantly lower than M1.5, M6, and M9 (P < 0.05), and the xylanase at M18 was significantly higher than M1.5, M23, and M27 (P < 0.05). 16S rRNA sequencing data and the Linear discriminant analysis showed that thirty-three bacteria were identified as biomarkers among ages and diets. The age and diet contributed 7.98% and 32.49% to the rumen bacteria community using the variation partitioning approach analysis. The norank_f_p-251-o5 was significantly and positively correlated with age (r = 0.83, P < 0.01), while Eubacterium was significantly and negatively correlated with age (r = -0.84, P < 0.01). Dietary fiber showed a strong correlation (r > 0.80, P < 0.01) with Lachnospiraceae, NK4A214_group, Saccharofermentans, Clostridia, Pseudobutyrivibrio Bacteroidales_UCG-001. These genera also negatively correlated with dietary crude protein and starch (r < - 0.80, P < 0.01). All these bacteria were significantly correlated with A/P, acetate, and urease (r > 0.5, P < 0.05). These findings collectively indicated that diet drives the great ability to shape the rumen bacteria community and function than age.
Uncovering the Structure and Function of Microbial Communities Formed During Periodic Tilling of TNT and DNT Co-Contaminated Soils
