Phytochemicals are a potential alternative to antibiotic growth promoters. This study evaluated the effects of phytochemicals (curcuminoids, trans-cinnamaldehyde, and piperine) and monensin on performance and ruminal fermentation during the transition period in grazing dairy cows. In a complete randomized design, 60 Holstein cows (36 multiparous, 24 primiparous; 9 fistulated) were assigned to (1) control (CTL), (2) monensin (MON, 0.30 g/cow/day), or (3) phytochemicals (PHY, 50 g/cow/day) treatment from 30 days prepartum to 60 days postpartum. Prepartum, cows received a total mixed ration (TMR); postpartum, they grazed between a.m. and p.m. milking and were supplemented with TMR. Ruminal fermentation was evaluated at −7, 30, and 60 days postpartum. Prepartum dry matter intake was lower in MON primiparous cows than in CTL and PHY. Additives increased milk yield and lactose percentage in primiparous cows. PHY cows had lower acetate, higher propionate, and reduced acetate-to-propionate and ketogenic-to-glucogenic ratios at 60 days postpartum. MON reduced prepartum protozoa, while PHY increased prepartum branched-chain volatile fatty acids (BCVFAs). Both additives decreased BCVFA and protozoa postpartum. Additives reduced ammonia at 30 days, but only PHY persisted at 60 days. MON and PHY improved primiparous performance, enhanced ruminal fermentation, and promoted glucogenic fermentation while reducing ammonia and protozoa.

Two experiments evaluated the effect of a multispecies fungal complex (BP, BIOPREMIX MX®, Ruminal Fermentation Tech, Uruguay). In Experiment 1 (E1), the impact of adding BP to a total mixed ration (TMR) on ruminal fermentation profile and TMR in situ degradation kinetics was assessed. In Experiment 2 (E2), the effect of adding BP to various substrates on in vitro fermentability was examined. In E1, 4 Holstein cows with rumen cannulas were randomly assigned to Control (TMR with forage:concentrate ratio 75:25) or Control + 120 g/cow/d of BP (BP) and received ad libitum TMR for 30 days. Samples of TMR were ruminally incubated to estimate in situ degradation kinetic. Ruminal pH, ammonia, and volatile fatty acids (VFA) concentrations were measured just before feeding, 4 h and 8 h post feeding. In E2, a factorial arrangement included two BP levels (0 -Control or 6.5 g BP per kg dry matter incubated-WBP) and 8 substrates. In vitro gas production kinetics (GPk), dry matter digestibility (IVDMD), methanogenic potential (CH4), partitioning factor (PF), VFA, and microbial crude protein (MCP) were estimated. The BP increased proportion of propionate (P ≤ 0.05) and reduced ketogenic:glucogenic ratio and Lag phase of NDF (P ≤ 0.05). WBP tended to increase IVDMD, and substrate affected GPk, IVDMD, CH4, PF, VFA and MCP (P ≤ 0.01). Overall, BP improved ruminal metabolism favoring a more glucogenic profile, a shortening Lag phase in NDF degradation, and increasing IVDMD.

"Replacing corn by crude glycerol on in vitro fermentation kinetic of complete diets for dairy cows" published on 28 Nov 2014 by Wageningen Academic.

The objective of this study was to evaluate the effects of sodium monensin (MON) and a phytochemical mixture (PHY) in dairy cows grazing alfalfa and supplemented with total mixed rations (TMR) on the: 1) neutral detergent fiber (NDF) degradability of alfalfa hay (AH), 2) in-situ organic matter digestibility (ISDom) of different feeds (four cultivated pastures, AH, pre- and postpartum TMR, and a simulated diet of alfalfa+postpartum TMR), and 3) ruminal fermentation profile. Nine rumen-fistulated Holstein cows were randomly assigned to one of three treatments: control (C), MON (0.30 g/cow/day), or PHY (50 g/cow/day). Additives were incorporated into the concentrate portion of the TMR from 30 days prepartum to 60 days postpartum. NDF degradation kinetics of AH and ISDom were determined between days 56 and 60 postpartum. Rumen fluid was collected at 0, 4, 8, 16, and 24 h after feeding to measure pH, ammonia nitrogen (NH3-N), volatile fatty acids (VFA), and protozoa counts. Both additives reduced the ISDom of the prepartum TMR (P<0.05) and the NDF degradation rate of AH (P<0.05) without affecting its potential degradability. They also promoted a more gluconeogenic VFA profile (P<0.05) and decreased protozoa counts (P<0.05). PHY further reduced NH3-N concentrations compared with MON and C (P<0.05). In conclusion, MON and PHY improved ruminal fermentation efficiency without affecting the potential for NDF degradation and PHY additionally enhanced nitrogen utilization, highlighting its potential as a natural alternative to MON in pasture-based dairy systems supplemented with mixed rations.