Improvement of fiber digestion and lowering of ruminal methane

(1)研究了添加丝兰提取物（YS）和/或异硫氰酸烯丙酯-环糊精（Al-CD）配合物对体外瘤胃甲烷产量和瘤胃发酵的影响。YS可使瘤胃原虫数量减少，Al-CD无明显变化。两种化合物均降低了瘤胃乙酸的摩尔比，提高了瘤胃丙酸的摩尔比。在6小时的孵育过程中，这两种化合物对甲烷的产生抑制了20- 80%。然而，当添加更多的添加剂时，纤维的消化会有所减少。本研究还以牛为试验对象，研究了YS对体内甲烷产量的影响。在干草加精料（1.5∶1）的饲粮中分别添加0.5%和1%的YS。添加0.5%时，瘤胃甲烷产量略有下降，添加1%时，瘤胃甲烷产量下降20%。YS的添加也降低了原生动物的数量和氨的浓度。由此可见，在氨化稻草饲粮中添加紫云英青贮和菜籽粕可以提高羔羊的生产性能和瘤胃发酵效率。在体外瘤胃发酵试验中，对未经处理和蒸汽预处理的稻草进行纤维素酶处理均有较好的效果。(2)研究了小母牛从出生到青春期血浆中生殖激素浓度的变化。观察每周或每天的激素变化。从大约10天到9个月大的小母牛，卵泡刺激素浓度的每日变化表明，在7- 8天的周期内，激素变化的周期是一致的。在出生时，类固醇激素的浓度高于其他任何年龄。然而，从出生到1周龄，促性腺激素水平上升。这些观察结果可能对上述饲料添加剂的使用有所帮助。

(1) Effect of addition of Yucca schidigera extracts (YS) and/or allyl isothiocyanate-cyclodextrin (Al-CD) complex on in vitro ruminal methane production and rumen fermentation was studied. Number of ruminal protozoa was decreased by YS, but unchanged by Al-CD. Molar proportion of ruminal acetic acid decreased, while that of propionic acid increased by both compounds. Methane production was inhibited by both compounds by 20-80 % during 6 hr incubation. However, fiber digestion was somewhat reduced when higher amounts of additives were administrated.The effect of YS on methane production in vivo was also studied by usinig cattle. YS was added to the diet consisted of hay plus concentrate (1.5 : 1) at the level of 0.5% and 1% of diet. Ruminal methane production was decreased slightly in the case of 0.5% addition, and decreased by 20% in the case of 1% addition. The number of protozoa and concentration of ammonia were also decreasd by the addition of YS.It was clarified that the supplement of Chinese milk vetch silage and rapeseed meal can increase the performance and rumen fermentation efficiency in lambs given ammoniated rice straw based diet. Cellulase treatment of untreated and steam pre-treated rice straw were shown to be effective in in vitro rumen fermentation.(2) Changes in plasma concentrations of reproductive hormones in heifers from birth to puberty was studied. Weekly or daily hormonal changes were observed. Daily changes in the concentration of follicle-stimulating hormones showed consistent cycle of hormone changes over a 7- to 8-day period in heifers from approximately 10 days to 9 months old. At birth, the concentrations of steroid hormones were higher than those at any other age. Gonadotropin levels, however, increased from birth to 1 week of age. These observations may be helpful in the case of the use of feed additives mentioned above.