Growth, reproduction and herbage utilization in Japanese Black and Brahman sired crossbred cow and their calves

本研究旨在探讨引进婆罗门种质对提高日本肉牛的放牧性能、牧草利用率和生长潜力是否有效。对婆罗曼(Z)×日本黑(B)、日本短刺(N)、荷斯坦(H)*和BB牛的F_1代牧草利用率进行了评价。F_1代谢物采食量超过BB。放牧前后牧草中NDF和TDN含量(%)的差异表明，放牧前后牧草对NDF和TDN的单位体重摄入量均大于BB。用重乳重法估测犊牛产奶量，Z-H、ZN和NN最大，BB最小，ZB和BN居中。说明母本品种对产奶量的影响大于父本品种。母牛平均日增重以ZH、ZN和NN最大，BB最小，ZB和BN居中。日增重与母猪产奶量之间存在一定的对应关系。对1/4Z(BB*XZB，ZN，ZH*)和BB的犊牛的日增重、牧草利用率和放牧行为进行了评价。每代谢体质量的日增重和牧草采食量的1/4Z均大于BB。两组间干物质消化率和蛋白质消化率差异不显著，但1/4Z组的纤维消化率和放牧时间分别高于BB组和BB组。结果表明：(1)婆罗曼杂种F_1的放牧性能优于日本品种，特别是日本黑牛；(2)1/4婆罗门杂交犊牛存在上述特点。

This study was carried out to examine whether introduction of the germ plasm of Brahman breed was effective or not for increasing the grazing ability, herbage utilization and growth potential of Japanese beef cattle.l. Herbage utilization in grazing was evaluated for F_1 of Brahman(Z)* X Japanese black(B), Japanese Shorthorn(N)and Holstein(H)* and BB cows. F_1 exceeded BB in herbage intake per metabolic body weight. F, was larger in both intakes of NDF and TDN per body weight than BB, supporting from differences of their contents(%)within herbage in pasture before and after grazing.2. In milk yield estimated by weig-suckle-weigh method of calves, Z-H, ZN and NN were largest and BB was smallest, ZB and BN were intermediate. These indicated that effects of breed on milk yield were larger in dam breed than in sire breed. Average daily gains(ADG)of calves from dam groups were largest in ZH, ZN and NN and smallest in BB, ZB and BN were intermediate. ADG was corresponding to milk yield of dam.3. ADG, herbage utilization and behavior in grazing were evaluated for calves of 1/4 Z(BB* X ZB, ZN, ZH*)and BB. 1/4 Z was larger in both of ADG and herbage intake per metabolic body weight than BB. There were no differences in dry matter and protein digestibilities between two groups, but 1/4 Z tended to be, respectively, higher in fiber digestibility and longer in grazing time than BB. It was suggested from these results that 1/4 Z had more nutrient intakes during grazing than BB.These results demonstrated that(1)Brahman crossbred F, was superior to Japanese beef breeds, especialy Japanese Black in grazing ability, (2)these characteristics were existing in 1/4 Brahman crossbred calves.