粗飼料源の違いが泌乳牛の乳量と乳成分に及ぼす影響

Effect of Various Roughage Source on Milk Yield and Milk Composition in Dairy Cows

熊谷 元

平山 啓一郎

石本 歩

池田 恭介

三谷 克之輔

生物生産学研究

Journal of the Faculty of Applied Biological Science, Hiroshima University

粗飼料の違いが泌乳牛の乳量と乳成分に及ぼす影響を調べるため、ホルスタイン泌乳牛9頭を用いてバヒアグラス、チモシー及びアルファルファ乾草を給与する3×3のラテン方格法による試験を2回行った。試験1ではトウモロコシサイレージを、試験2ではイタリアンライグラスサイレージ給与した。一方飼料中の栄養成分の組成とその in vivo 消化率の測定を行った。アルファルファ乾草の粗蛋白質含量とその消化率及びカルシウム含量はチモシー乾草とバヒアグラス乾草に比べて非常に高かった。バヒアグラス乾草の粗繊維の含量とその消化率はチモシー乾草とアルファルファ乾草に比べて高かった。イタリアンライグラスサイレージの粗蛋白質の含量と消化率はトウモロコシサイレージに比べて低かった。試験1・2ともにバヒアグラス乾草給与区の乾物摂取量及び乳量はチモシー及びアルファルファ乾草給与区に比べて低い傾向が認められた。乳脂肪率はアルファルファ乾草給与区が他の区に比べて低く、乳蛋白率は逆に高い傾向を示した。試験2は試験1に比べて乾物摂取率が低く、試験開始時からの乳量の減少が著しかった。重回帰分析の結果、乳量は乾物摂取量と体重を説明変数とする回帰式で、乳脂率と乳糖率は乳量と体重を説明変数として含む回帰式で示された。粗飼料源の違いが泌乳牛の乳量及び乳成分に影響する可能性が示唆された。

To investigute the effect of different roughage source on milk yield and composition in dairy cows, two experiments were conducted by using 9 Holstein cows. The cows were allocated to 3 x 3 Latin square model and fed bahiagrass hay, timothy hay and alfalfa hay. Corn silage and Italian ryegrass silage were fed in trial 1 and trial 2, respectively. The composition and in vivo digestibility of nutrients in diets were measured. The concentration and digestibility of crude protein and the concentration of calcium in alfalfa hay were quite higher than those in timothy and bahiagrass hay. The concentration and digestibility of crude fiber in alfalfa hay were lower than those in timothy and bahiagrass hay. The concentration and digestibility of crude protein in Italian ryegrass silage were lower than those in corn silage. In both of the trials, the dry matter intake and milk yield of cows fed bahiagrass hay tended to be lower than those of cows fed timothy and alfalfa hay. The concentrations of milk fat from cows fed alfalfa hay were the lowest in the treatment groups. Conversely, the concentrations of milk protein from cows fed alfalfa hay were the highest in the treatment groups. The rate of dry matter intake in cows of trial 2 were lower than that in cows of trial 1. The decrease of milk yield in trial 2 since the beginning of the experiment was larger than that in trial 1. The milk yield was given by the regression equation of the independent variables of dry matter intake and liveweight. The concentrations of milk fat and lactose were given by the regression equation of the independent variables including milk yield and liveweight. The results from this experiment suggest that milk yield and milk composition in dairy cows may be affected by the difference of roughage source.

粗飼料

乳成分

乳量

泌乳牛

Dairy Cow

Milk Composition

Milk Yield

Roughage

畜産業 [ 640 ]

日本語

広島大学生物生産学部

農林水産研究情報センター

[ISSN] 1341-691X

[NCID] AN10409040