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 -

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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