An in vitro rumen gas production technique was employed to determine the methane production and fermentation characteristics of Leymus chinensis and Medicago ruthenica at differing harvest dates (May 15, May 30, June 30, July 30, August 30 and September 30), which are sequential phases within a single continuous growth of two 10-year-old pastures. To quantify the rate of degradation and compare in vitro rumen fermentation characteristic, a logistic-exponential model, where initial gas volume was zero (LE0), was used to fit gas production and methane output results. Dried, milled forage samples were incubated in vitro for 72 h at 39°C and gas production was recorded intermittently throughout the incubation and gas samples were collected to measure methane production. Results showed that there were significant interactions between species and harvest for all chemical composition variables (P<0.001) and condensed tannin content (P<0.001). L. chinensis produced more total gas and methane than M. ruthenica (P<0.001). Both total gas and methane production decreased lineally (P<0.001) with advancing harvest date. The degradation rates of L. chinensis and M. ruthenica harvested on September 30 were lower than those on the other harvest dates (P<0.01). M. ruthenica fermented fluid had higher concentration of ammonia N (P<0.05) and molar proportions of isobutyrate (P<0.01), valerate (P<0.001) and isovalerate (P<0.01) in total volatile fatty acids than L. chinensis. Furthermore, concentration of isovalerate decreased cubically with advancing harvest date (P<0.05). In conclusion, M. ruthenica produced less methane than L. chinensis and the total gas and methane production decreased with advancing harvest date for both species, which may be due to the changes in contents of chemical compositions and condensed tannin in forages.

The experimental knowledge on the role of oxidative stress, and beneficial and detrimental effects of plant derived antioxidants in male and female animal reproduction are reviewed in this article. Free radical-induced oxidative stress in animal reproduction causes great loss to livestock industry. Antioxidant therapy has been implicated to be effective in preventing diseases resulted from oxidative stress. Considering the advantages of lower side effects of natural antioxidants than those of synthetic antioxidants, plants or their extracts have been extensively utilized in animals. Although many advances have been gained on application of plant derived antioxidants in alleviating oxidative stress, debatable issues still exist. Because many opposite effects were observed even using plant extracts containing similar bioactive substances in the same animal species. Therefore, plant derived antioxidants, like free radicals, are “double-edged swords” in animal reproduction, representing that they may exhibit beneficial or detrimental effects in animal reproduction, including spermatogenesis, semen functions, estrous cycles, ovulation, ovary functions, endometrium, embryo development, and pregnancy. Besides dose-dependent manner as an explanation of plant extracts’ dual function, future studies are needed to investigate the mechanism of double-edged actions of plant derived antioxidants in different animal reproduction systems.

The experimental knowledge on efficacy, possible modes of action and aspects of application of Chinese herbs as feedadditives for animal production are reviewed in this article. Chinese herbs commonly contain protein, carbohydrate, fat,vitamins, and mineral which are necessary nutrients to the growth of animal. Polysaccharide, organic acid, alkaloids, andessential oils involved in Chinese herbs can improve the immune function of livestock. Currently, numerous studies havedemonstrated anti-oxidative and anti-microbial efficacy and the assumption that Chinese herbs may improve the flavor ofmeat, which has been confirmed by some observations, but the mode of this action is still unclear. Moreover, severalobservations support the hypothesis that herbal feed additives may favorably affect gut functions (e.g., enzyme activity,microbial eubiosis) in vitro. Such effects may explain a considerable number of practical studies with livestock reportingimproved production performance after providing herbal feed additives. In summary, available evidence indicates thatherbal feed additives may have the potential to add to the set of non-antibiotic growth promoters for use in livestock, suchas organic acids and probiotics. However, a systematic approach toward the efficacy, mode of action and safety of herbalcompounds used as feed additives for animal production seems to be required in the future.