水牛と子牛のルーメンの生態についての比較研究

A comparative study on rumen ecology of water buffalo and cattle calves under similar feeding regime.

• Qiyan Wang
• Xiaomei Gao
• Yunyan Yang
• Caixia Zou
• Yingbai Yang
• Bo Lin

抄録

水牛（Bubalus bubalis）の雄の子牛と同年齢（10±5日）のホルスタイン（Bos taurus）の子牛を12頭選び、両種間の成長性能や飼料転換率の違いのメカニズムを探った。実験期間は吸汁期間33日と離乳後40日である。授乳期には両種とも同量のミルクを与え、離乳期前後にはスターターとオート麦草を自由に与えた。実験期間中の飼料摂取量、発育能力、鼻腔内発酵パラメータ、鼻腔内微生物群集を測定した。その結果、水牛とホルスタインの子牛の間には、吸汁期の成長性能と飼料摂取量に差は見られなかったが、飼料利得比（F/G）はホルスタインの子牛よりも高かった（p>0.05）。離乳後は、ホルスタインの子牛の方がスターター摂取量が多く、水牛の方が牧草摂取量が多いことから、ホルスタインの方が成長力が高く、F/G比が低いことがわかった(p<0.05)。ホルスタインの子牛のルーメンは水牛に比べてプロピオン酸が高く、アセテートと分岐鎖脂肪酸が低かった(p<0.05)。水牛のルーメンはホルスタイン子牛と比較して、観察された細菌種の数とシャノン多様性が高かった。また、ホルスタイン種の子牛のルーメンには、バクテロイデス属やプレボテラ属に属する細菌が多く(p<0.05)、ホルスタイン種の子牛のルーメンには、水牛のルーメンに比べてフェルミキュートス属や線維化細菌のルミノバクター属やルミノコッカス属が少なかった(p<0.05)ことが明らかになった。結論として、水牛の子牛は、牛の子牛よりも細菌群集と繊維の消化が良いことが明らかになった。

In all, 12 male water buffalo (Bubalus bubalis) calves and Holstein (Bos taurus) calves of similar age (10 ± 5 days) were selected to explore the mechanism underlying the differences in growth performance and feed conversion ratio between the two species. The experiment contains 33 days of sucking period and 40 days of post-weaning period. Both calves were fed the same amounts of milk in sucking period, and starter and oat grass were supplied ad libitum both before and after the weaning period. Feed intake, growth performance, ruminal fermentation parameters and the ruminal microbial community were measured the during experiment period. Results showed no differences in growth performance and feed intake between the two species in sucking period; however, the feed/gain ratio (F/G) of the water buffalo was higher than that of Holstein calve (p > 0.05). After weaning, the intake of starter by the Holstein calf was higher while intake of grass by the water buffalo was higher resulting in higher growth performance of and a lower F/G ratio for Holstein (p < 0.05). The rumen of Holstein calf showed higher levels of propionate, lower levels of acetate and branched-chain fatty acids than that of water buffalo during both periods (p < 0.05). The rumen of water buffalo showed a higher number of observed bacterial species and Shannon diversity as compared with that of Holstein calf. The members belonging to the bacterial phylum Bacteroides and genus Prevotella in the rumen of Holstein calf were higher (p < 0.05), while Firmicutes and fibrolytic bacteria Ruminobacter and Ruminococcus were lower (p < 0.05) than that of water buffalo. In conclusion, the water buffalo calves demonstrated clearly of having significant population of bacterial community and better fibre digestion than those of cattle calves.

© 2020 The Authors. Veterinary Medicine and Science Published by John Wiley & Sons Ltd.