Effects of 9,10 anthraquinone on ruminal fermentation, total-tract digestion, and blood metabolite concentrations in sheep.

The objective of this study was to evaluate the effects of adding 9,10 anthraquinone, a known inhibitor of methanogenesis and sulfate reduction, on blood metabolites, digestibility, and distribution of gas in sheep. In all experiments, we fed a complete pelleted diet that contained 17.5% crude protein and 24.5% acid detergent fiber. In an 8-wk study, feeding up to 66 ppm (dry matter basis) of 9,10 anthraquinone had no adverse effects on blood metabolites including indicators of normal enzyme function, mineral concentrations, and hematological measurements. Feeding 9,10 anthraquinone had no effect on average daily gain, although sheep fed a diet containing 66 ppm of 9,10 anthraquinone numerically gained the least weight. The ruminal molar proportions of acetic acid were decreased (P < 0.05) and the molar proportions of propionic acid were increased (P < 0.05) in sheep fed 1.5 and 66 ppm 9,10 anthraquinone when compared to those fed an unsupplemented diet. In a digestion trial, 9,10 anthraquinone (33 and 66 ppm) had no effect on the apparent digestion of nutrients in the total gastrointestinal tract. In a metabolism study, ruminal gasses were collected by rumenocentesis and analyzed for methane and hydrogen concentrations. Feeding 500 ppm of 9,10 anthraquinone to sheep resulted in a decrease (P < 0.07) in the concentration of methane, but an increase (P < 0.05) in hydrogen concentration of ruminal gas throughout the 19 d of feeding. There was no indication of ruminal adaptation throughout this time. These results are the first to show that 9,10 anthraquinone can partially inhibit in vivo rumen methanogenesis, which supports previous in vitro findings. In addition, at the concentrations used in this study, 9,10 anthraquinone was not toxic to ruminants.

The effect of preservatives based on propionic acid on the fermentation and aerobic stability of corn silage and a total mixed ration.

For 3 successive yr, whole-plant corn was ensiled in laboratory silos with low percentages of silage preservatives, the primary active ingredient of which was propionic acid. Preservatives were added to forage just prior to ensiling at rates of 0.1 to 0.2% of the fresh forage weight. In all 3 yr, treatments had minor effects on fermentation end products, except that the concentration of propionic acid was greater because of its addition. The mean low and high percentages of preservatives increased aerobic stability of the treated silages by 19 and 57 h, respectively, in Experiment 1 and by 17 and 38 h, respectively, in Experiment 2. In Experiment 3, aerobic stability was improved by > 90 h by preservatives (0.2% addition). In a lactation study, a total mixed ration (46% dry matter) was mixed without or with (0.2 or 0.3%) a stabilizer that was designed to prevent spoilage in the feed bunk. The high dose resulted in orts with a lower pH and temperature after 24 h in the feed bunk. However, dry matter intake and milk production were unaffected by treatments. Chemical preservatives based on propionic acid added at low rates did not affect fermentation but were effective in the reduction of heating in corn silage and in a total mixed ration.