Maternal Influences on Early Calf Rumen Volatile Fatty Acid Profile

Microbial fermentation and subsequent production of VFA serve as a major energy source for the host. We hypothesized that the rumen microbiome is established at or near birth and microbial fermentation is subject to maternal influences that can affect long-term feed efficiency. Our objective was to determine how mode of delivery and rearing affected VFA production in young calves. Bred mature Charolais cows were randomly allocated to one of three treatment groups: control (CON; n = 8), bottle reared (BOT; n = 8), and caesarian section (CSECT; n = 8), where CON was vaginal birth and raised by their dam; BOT was vaginal birth, then removed 24 h post-parturition, and raised on commercial milk replacer; and CSECT was born via caesarian section and raised by their respective dams. Calf rumen fluid was collected via oral lavage and flash frozen on d 1, 3 and 28 of age. Samples were analyzed by GLC to determine VFA concentrations. The MIXED procedure of SAS was used to determine the effects of day, treatment group, and the interaction on acetate:propionate, total VFA concentration, and individual VFA concentrations (mM). Means were separated using LSD and differences were considered significant when P ≤ 0.05 and tendency when 0.05 < P ≤ 0.10. Results showed a main effect of day (P < 0.05) for total VFA, acetate:propionate, acetate, propionate, and butyrate concentrations. Total VFA (P < 0.05) increased with day of age. Acetate concentrations were not different (P ≥ 0.05) on d 1 and 3, but were less (P < 0.05) on d 28. Alternatively, butyrate concentrations were less (P < 0.05) on d 28 compared to d 1 and 3, which were similar (P = 0.86). Propionate was intermediate (P < 0.05) on d 28 to d 1 and 3. Acetate:propionate was not different (P = 0.24) between d 1 and 28, but was less (P < 0.05) on d 3. There were day by treatment interactions for isobutyrate and valerate (P ≤ 0.03) and a tendency for isovalerate (P = 0.08) where concentrations increased with day and greatest (P < 0.05) concentrations reported within the BOT and CSECT treatments on d 28. We conclude that both age and maternal influences may alter VFA production in calves, which may have implications for production efficiency later in life.