GROWTH,PHYSIOLOGICAL FUNCTION AND MEAT PRODUCTION IN CROSSBRED F_1 OF LIMOUSIN (*) *JAPANESE SHOPTHORN (*) CATTLES

本研究旨在探讨利木赞(L)品种的种质导入是否能有效地改善日本短角牛的生长潜力、饲料利用率、生理机能和产肉量。(1)对LN、NN和日本黑(BB)犊牛进行体重、日增重、饲料利用率的测定。从出生到12月龄，BW和DG的LN显著大于NN和BB，但以后两者之间的差异不显著。在8月龄和16月龄时，LN和NN的饲料利用率没有差异。(2)对LN、NN和BB在放牧和安家期间的血液成分和循环激素(GH、IGF-1、Insulin)水平进行了测定，并确定了它们性状的遗传差异。精料饲喂后，LN的胆固醇、甘油三酯、血糖、生长激素和胰岛素水平在8月龄时显著高于NN，但以后仅在胆固醇和血糖方面存在差异。(3)育肥开始时，LN和NN的皮下脂肪厚度超声测定值没有差异，但3个月后，LN显著大于NN。(4)LN的屠体性状与NN差异不显著，但在屠体重量和眼肌中，LN有大于NN的趋势，而肋骨厚度则有小于NN的趋势。LN在C18：0组比NN组大，在C18：1组比NN组小，饱和脂肪酸占总脂肪酸的百分比也比NN组大。结果表明，利木赞组与NN组在生长前期的日增重、血液成分和激素水平上都表现出了交配效果，但在高精料饲喂的日本育肥制下，对饲料利用率和产肉量影响不大。

This study was carried out to examine whether an introduction of the germ plasm of Limousin (L) breed was effective or not for improving the growth potential, feed utilization, physiological function and meat production of Japanese Shorthorn (N) cattle.(1) Body weight (BW), daily gain (DG), feed utilization were evaluated for calves of LN,NN and Japanese Black (BB). LN was significantly larger in BW and DG than NN and BB from birth to 12 month of age, but later, there was no difference between them. There were no differences in feed utilizationin between LN and NN at both age of 8 and 16 months.(2) Blood components and circulating levels of hormones (GH,IGF-1, Insulin) were evaluated for calves of LN,NN and BB in the term of grazing and housing, and genetic differences in their traits were determined. In response after feeding of concentrate, LN was higher in levels of cholesterol, trigriceride, glucose, GH and insulin than NN in age of 8 month, but later, there were differences between them only in cholesterol, and glucose.(3) Ultrasonic mesurements of subcutaneous fat thickness were no differences between LN and NN in start of fattening, but after three months, LN was signifficantly larger than NN.(4) Carcass traits were no signifficant differences between LN and NN,but LN tended to be larger in caracass weight and eye muscle and smaller in rib thickness than NN.(5) In fat acid components (%) of four position fat tissues, LN was larger in C18 : 0, and smaller in C18 : 1 than NN,and percentage of saturated fat acid to total fat acid were larger in LN than NN.These results demonstrated that the mating effectiveness of Limousin * to NN * were shown in DG,blood components and hormone levels in earlier growth stage, but there were not effective in the feed utilization and meat production under the Japanese fattening system of much concentrate feeding.