Studies on the genetic mechanism of the marbling trait in carcasses of dairy steers.

奶牛胴体大理石花纹性状遗传机制研究

• 批准号: 60860030
• 负责人: NAMIKAWA Kiyoshi
• 金额: $ 4.22万
• 依托单位: Kyoto University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Developmental Scientific Research
• 财政年份: 1985
• 资助国家: 日本
• 起止时间: 1985 至 1986
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60860030/
• 关键词: Dairy steer; Marbling trait; genetic mechanism; separable fat percentage; image-analysis; ロース断面積; 肉質の客観的評価

In the previous studies, an outstanding Holstein sire(A),Which was characterized with very high drgree of marbling in his progeny steer carcasses,was detected. In addition,semen of father's(B) and mother's sides(C) half-sib sires were obtained.These 3 sires were mated with Holstein cows to get their progeny. Of each sire, 3 steer calves were alloted to 3 fattening groups in the Exp. 1. All steers were slaughted at about constant body weight 650kg and at closely 21 months of age.The carcass weight of the 3 group were 360,376,379kg,respectively. the percentage of separable fat were 35.6,31.3 and 32.3 in average of 3 groups,showing higher percentage in the progeny group of sire A. The average marbling scores,calculated from scores recorded from the 5th thoracic to the 6th lumber vertebrae, i.e. 15 sections in total, were 2.5, 2.0, 2.0 respectively. It was also noticed on the degree of marbling that high degree of marbling at the fore section did not maintained at the rear sections,such as rear thoracic and lumber vertebrae sections.In the Exp.2., 4 steers of sire A were finished at 650 and 750kg body weight. Two steers slaughterd at 750kg B.W. spent about additional 8 months,with 5% increse in separable fat and without any level-up in the degree of marbling.It was estimated that the superiority of sire A must be brought about additive effect of father's and mother's sides.As the first step of objective evaluation on carcass traits,an image-analizer were applied for measurements on rib-eye area and the proportion of lean meat area at the surface of rib section. Considerably high correlations between two measurements were observed.

在以前的研究中，发现了一头优秀的荷斯坦公牛(A)，其后代的肉牛身体上有非常高的大理石花纹。此外，还采集了父本(B)和母本(C)同父(B)和母牛(C)半同胞的精液，与荷斯坦母牛交配，得到后代。试验将3头公牛随机分成3个育肥组。1.在接近21月龄、体重约为650 kg的条件下屠宰试验牛，3组的屠体重分别为360、376、379 kg。可分离脂肪百分比平均为35.6%、31.3%和32.3%，其中父本后代比例较高。按第5胸椎至第6腰椎共15节的评分计算，平均大理石花纹评分分别为2.5、2.0、2.0。在大理石花纹的程度上也注意到，前部大理石花纹在后部如胸椎和腰椎没有保持很高的大理石花纹。在试验2中，4头公牛A完成了650和750公斤体重。两头体重750 kg左右的公牛，在可分离脂肪水平提高5%的情况下，经过8个月左右的屠宰，大理石花纹程度没有提高，估计父本A的优势必然是父本和母本的加性效应。作为对屠体性状客观评价的第一步，应用图像分析仪对肋眼面积和肋骨表面瘦肉率进行测量。观察到两个测量之间有相当高的相关性。