Four Holstein steers fed with Sorghum silage were used to examine the effect of fumaric acid supplementation (20g/kg. diet dry matter (DM)) on methane production, rumen fermentation, blood metabolism and feed digestibility.The protozoal population in the rumen was unaffected by fumaric acid supplementation.The postprandial ruminal concentration of ammonia-N decreased, and that of total volatile fatty acids tended to be higher with fumaric acid supplementation.The proportion of ruminal acetic acid was unaffected, but that of propionic acid increased and that of butyric acid decreased by fumaric acid. The postprandial blood plasma concentration of glucose was increased, whereas that of urea-N was decreased by fumaric acid. The plasma concentration of most of free amino acids was unaffected. Daily methane production decreased by 23.0% and carbon dioxide production decreased by 20.5% with fumaric acid supplementation. Apparent digestibility of dry matter and of neutral detergent fiber were not influenced by fumaric acid. These results indicated that fumaric acid was converted to propionic acid by rumen microorganisms, and that methane production from the rumen was reduced without lowering the ability to digest dietary fiber. However, some dietary conditions that alter the effectiveness of fumaric acid and the long term effect remain to be examined.

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The aim of this study was to investigate the effects of three herb supplementations on blood metabolites, hormones, antioxidant activity, immunoglobulin (Ig) G concentration, and ruminal fermentation in steers. Four Holstein steers in a 4×4 Latin square design received four herb treatments. The treatments consisted of the steers' regular diets with addition of: 1) nothing (control), 2) peppermint, 3) clove, and 4) lemongrass at 5% of the diet (DM basis). Clove supplementation increased the plasma concentration of cholesterol by about 10% (from 79 to 87 mg/dl). Peppermint and lemongrass feeding resulted in an increase in the concentrations of plasma urea nitrogen (from 5.9 to 6.9 and 6.4 mg/dl, respectively). The three herb treatments had no effect on other metabolites and hormones. Steers receiving clove supplementation showed a higher plasma antioxidant activity. The three herb treatments caused lower concentrations of IgG in the blood. Peppermint and lemongrass feedings increased, and clove feeding decreased ruminal concentrations of ammonia. There were no significant differences in VFA concentrations among herbal treatments, except for the decrease in propionate concentration in steers receiving clove treatment. This study suggested that clove feeding changed cholesterol metabolism and increased antioxidant activity in plasma, and feeding of three herbs affected immunity system and ruminal fermentation in steers.

The characteristic smell of cow milk was suppressed when herbs were consumed by lactating dairy cows. But it is unclear whether or not peppermint ingestion affects the nutritional and milk production parameters in lactating dairy cows. The objective of this study was to examine the effect of peppermint feeding to lactating dairy cows on nutrient digestibility, energy metabolism, ruminal fermentation and milk production. Eight Holstein cows were given a diet supplemented with or without 5% of dried peppermint per diet on a dry matter basis. The digestion of nutrients from cows fed the diet with peppermint was significantly lower than that of the control group. Energy loss as methane and methane released from cows receiving the peppermint treatment was significantly lower than that in the control cows. Peppermint feeding to cows resulted in the promotion of thermogenesis. However, ruminal fermentation and milk production were not affected by peppermint feeding. In conclusion, peppermint ingestion by lactating dairy cows reduces the nutrient digestibility and methanogenesis, and changes energy metabolism.

Anthocyanin in purple corn (Zea mays L.) has been reported to show several functional and biological attributes, displaying antioxidant, antiobesity and antidiabetic effects in monogastric animals. The objective of this study was to investigate the effect of feeding anthocyanin-rich corn (Zea mays L., Choko C922) silage on digestibility, milk production and plasma enzyme activities in lactating dairy cows. The cows were fed diets based on the control corn or the anthocyanin-rich corn silage (AR treatment) in a crossover design. The anthocyanin-rich corn silage-based diet had a lower starch content, nutrient digestibility and total digestible nutrients content when compared to the control diet. The milk yield, lactose and solids-not-fat contents in the AR-treatment cows were lower than in the control cows. The feeding of the anthocyanin-rich corn silage led to a reduction in aspartate aminotransferase (AST) activity and an increase in superoxide dismutase (SOD) activity in the plasma. These data suggest that the anthocyanin-rich corn has a lowering effect on AST activity with concomitant enhancement of SOD activity in lactating dairy cows. However, a new variety of anthocyanin-rich corn with good nutritional value is needed for practical use as a ruminant feed.