Studies on Growth and Meat Productivity of F_1 Cattle of Brahman X Japanese Black, Japanese Shorthorn, and Holstein Friesian . - Usefulness of the genetic character of Brahman Cattle -

用日本黑牛(BB)、日本短角牛(NN)和荷斯坦牛(HH)杂交的25头F1牛(ZB、ZN和ZB)，在东北大学实验场用澳大利亚进口婆罗曼(ZZ)精液进行人工授精。1.犊牛生长：F_1代初生重表现出杂种优势，分别为纯种的113%(ZB)、137%(ZN)和125%(ZH)。F_1代妊娠期比纯种延长5~7天，18个月龄体重比纯种重50公斤左右。2.粗饲料利用与基础代谢：研究了18月龄ZB和BB公牛对低品质蒂莫西干草粗饲料的利用。ZB组对中性洗涤纤维、酸性洗涤纤维和干物质的消化率均好于BB组，但对干草的采食量差异不显著。从呼吸频率、呼气频率和心率计算，ZB的基础代谢率低于BB。3.牧草行为和生长速度：F_1组…采草量更多的是纯种犬，而纯种犬几乎从不在白天捕食。F_1组每天步行距离为纯种的1.4~1.9倍，采食草种数、采食量和单位采食量生长速度均优于纯种。17~20月龄公牛在草场上145日龄的生长速度分别为93 kg(ZB：n=4)和37 kg(BB：n=8)，而开始时的平均体重是相同的。4.放牧抗病：F_1组表现出对牛泰勒虫病的抗性，一年内角蝇和家蝇的寄生量低于F_1.5组。育肥性能：F_1组育肥天数分别比NN和BB组缩短50天和90天。F_1组的背脂厚度较薄，眼肌面积较小，屠宰率较低。但是，从感官上来说，它们可以作为一种受欢迎的肉类流通。对肉的脂肪酸组成和分子量分布进行分析，F_1代具有婆罗门遗传特征。6.日本品种不像婆罗门那样基础代谢率低、粗饲料利用率高、放牧适应性好，具有显著的遗传特性和实用价值。较少

Twenty five of F_1 cattle(ZB,ZN and ZB) breeded by Japanese Black(BB), Japanese Short Horn(NN), and Holstein(HH) were produced in Experimental Farm of Tohoku University by means of A.I. with the semen of Brahman(ZZ) imported from Australia.1.Growth of F_1 calves: Heterosis were found on birth weights of F_1 and they are 113%(ZB),137%(ZN) and 125%(ZH) compared with purebreds. Gestation periods of F_1 groups were 5 to 7 days longer and body weights at 18 months of F_1 groups were about 50 Kg heavier than purebreds. 2.Utilization of roughage and basal metabolism: Utilization of roughage by 18 months old steers of ZB and BB with low quality timothy hay was investigated. Digestibility of neutral detergent fiber, acid detergent fiber and dry matter of ZB were better than BB, but there were no differences on intake of hay. Basal metabolic rate of ZB was lower than BB calculated from respiration rate, expiration and heart rate. 3.Behavior and growth rate on pasture: Grass intakes of F_1 groups … More were more than purebreds, whereas purebreds almost never took it in the daytime. Walking distance per day of F_1 groups were 1.4 to 1.9 times long, and it was suggested that number of species of grass intake , feed intake and growth rates per feed intake were better than purebreds. Growth rate of 17 to 20 months old steers for 145 days on pasture were 93Kg(ZB:n=4) and 37Kg(BB:n=8), in spite of same average body weight at beginning. 4.Disease resistance for grazing: F_1 groups showed the disease resistance for Bovine Theileriosis and number of parasite of Horn Fly and House Fly within a year were lower in F_1.5.Fattening performance of steers: Days of fattening in F_1 groups were 50 and 90 shorter than NN and BB, respectively. F_1 groups have thinner back fat thickness, smaller lib eye area and lower dressing percentage. But, sensuous test, they can circulate as a popular meat. Analysis of fatty acids of meat and molecular weight distribution, F_1have genetic characters of Brahman. 6.Japanese breeds do not have such lower basal metabolic rate, high utilization of roughage and good grazing adaptability as Brahman, and it have remarkable genetic characters and is useful. Less