Sanguinarine and resveratrol affected rumen fermentation parameters and bacterial community in calves

Plant extracts can be used in calf feed as alternatives to antibiotics, but their effects on colonization of microbial populations remains to be determined. Thus, we evaluated the effects of dietary plant extracts on rumen fermentation parameters and rumen bacterial community in calves, and we followed them up to 9 months of age to determine the persistence of any effects. Fifty-four female Holstein calves were randomly assigned to three treatments consisting of basal diet alone (MR group) or supplemented with sanguinarine (SAG group) or resveratrol (RES group) at 7 days of age. Body weight was measured at the beginning of the experiment and 2 or 6 months of age. Rumen fluid was sampled at 1, 2, 3, 4, 5, 6, and 9 months of age to monitor rumen fermentation parameters. Rumen samples at 3 and 6 months of age were used to analyze the bacterial community by amplicon sequencing. The copy number of Desulfovibrio and methanogenic archaea was determined using droplet digital PCR. The results demonstrated that ADG of calves was similar among groups during 7 d-2 m, 2 m-6 m and 7 d-6 m, respectively. At 3 months, ruminal pH was lower in the SAG and RES groups than in the MR group. The concentration of total volatile fatty acids (TVFA) was greater in the SAG group than in the MR group. At 4 months, the ammonia nitrogen (NH3-N) concentration and the molar proportion of butyrate were lower in the SAG group than in the other two groups. The molar proportion of acetate and the ratio of acetate to propionate (A:P ratio) were lower in the RES group than in the SAG group. The molar proportion of valerate was greater in the RES group than in the other groups. At 5 months, the NH3-N concentration was lower in the SAG group than in the other groups. The molar proportion of valerate was lower in the RES and SAG groups than in the MR group. No differences were observed in rumen fermentation parameters among groups at 1, 2, 6, and 9 months of age. The observed species, Chao1, and abundance-based coverage estimator (ACE) values were greater in the MR group than in the other groups at 3 months of age. The community structure of bacteria in the MR group was distinct from that of the SAG and RES groups at 3 months of age. Desulfovibrio population was increased by sanguinarine and resveratrol, whereas methanogenic archaea population was decreased by resveratrol. No difference was observed in alpha and beta measures among all groups at 6 months of age. In summary, dietary sanguinarine or resveratrol affected rumen fermentation parameters and bacterial community in calves during 3-5 months of age. No effects of plant extract on rumen environment was detected at 6 and 9 months of age.