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The objective of this study was to evaluate the effects of a novel Lactobacillus plantarum strain with high-antioxidant activity on antioxidant status, chemical composition and fermentation profiles of alfalfa silage ensiled at two dry matter (DM) contents. Fresh chopped alfalfa was wilted to two targeted dry matter (DM) contents of approximately 300 (low DM) and 400 (high DM) g/kg fresh weight and treated without or with a strain of L. plantarum 24−7 with high antioxidant activity. Forages were ensiled in vacuum-sealed polyethylene bags containing ∼600 g wilted forage for 60 d, with 5 replicates for each treatment. Alfalfa silage ensiled at low DM had higher concentrations of acetic acid and non-protein nitrogen (NPN) and lower concentrations of lactic acid, propionic acid and water soluble carbohydrates (WSC) than silages with high DM. Inoculation of L. plantarum 24−7 led to lower silage pH and lower concentrations of NPN, neutral detergent fiber (aNDF), acid detergent fiber (ADF), and higher WSC compared to the control silage at two DM contents. Inoculation increased aerobic stability of the forage ensiled at low DM but decreased that ensiled at high DM. In control silages, almost half of the α-tocopherol and β-carotene was degraded during ensiling, whereas inoculation with L. plantarum 24−7 increased α-tocopherol and β-carotene concentrations as well as the proportion of polyunsaturated fatty acids (PUFA) in ensiled alfalfa at both DM contents. Greater concentrations of β-carotene were observed in L. plantarum 24−7 treated-silage at low DM compared to silage at high DM. The application of L. plantarum 24−7 strain also increased total antioxidant capacity (T-AOC), glutathione peroxidase (GSH-Px) and catalase (CAT) activities of the alfalfa silage but decreased superoxide dismutase (SOD) and lipoxygenase (LOX) activities. These results indicate that L. plantarum 24−7 improved the fermentation quality and antioxidant status of ensiled alfalfa forage relative to the control silage.

The study was aimed at determining the importance of yeast (Saccharomyces cerevisiae) viability for reducing the severity of ruminal acidosis in cattle during and following an imposed acidosis challenge. Six ruminally cannulated beef heifers were used in a replicated 3 × 3 Latin square design and fed a diet consisting of 400 g/kg barley silage, 100 g/kg chopped grass hay, and 500 g/kg barley grain based concentrate (dry matter basis). Treatments were: (1) control (no yeast); (2) active dried yeast (ADY; 4 g providing 1010 colony forming units/g; AB Vista, UK); and (3) killed dried yeast (KDY; 4 g autoclaved ADY). The periods consisted of 2 weeks of adaptation (day 1–14), week 3 of baseline measurements (day 15–21) and week 4 of acidosis challenge (day 22–28). The challenge model involved restricting consumption of the TMR to 0.5 of ad libitum intake for 24 h (day −1; prechallenge) followed by adding barley grain (amount equivalent to 0.25 of DMI) directly to the rumen prior to feeding the TMR (day 0; challenge day). Data were collected from 0 to 24 h on the challenge day, 25–48 h post grain challenge (day 1 postchallenge) and during a 5-day recovery period. No treatment effects were observed on mean (P=0.40), nadir (P=0.37) and maximum (P=0.29) ruminal pH on the challenge day. Similarly, no treatment differences were observed for ruminal lactate (P=0.46) and total VFA concentrations (P=0.15) on the challenge day. However, proportion of ruminal propionate was increased (P=0.01) while caproate reduced (P=0.01) with ADY. The duration of time that pH