Bergen R, Miller S P, Wilton J W, Mandell I B
Department of Animal and Poultry Science, University of Guelph, Guelph, ON, N1G 2W1, Canada.
J Anim Sci. 2006 Mar;84(3):558-66. doi: 10.2527/2006.843558x.
Partial carcass dissection data from 1,031 finished crossbred beef steers were used to calculate heritabilities and genetic correlations among subcutaneous, intermuscular, and body cavity fat percentage and marbling score adjusted to slaughter age-, HCW-, fat depth-, and marbling score-constant endpoints. Genetic correlations were also calculated among these fat partitions with live growth and ultrasound traits evaluated in yearling beef bulls (n = 2,172) and steer carcass measurements. Heritabilities of the different fat partitions ranged from 0.22 (marbling score-constant body cavity fat) to 0.46 (HCW-constant marbling score). Genetic correlations between subcutaneous fat and intermuscular fat (rg = 0.16 to 0.32) and between intermuscular fat and body cavity fat (rg = 0.38 to 0.50) were more highly associated than subcutaneous fat and body cavity fat (rg = -0.08 to 0.05), indicating that fat depots are not under identical genetic control. Adjusting fat depots to different end points affected the magnitude but usually not the sign of the genetic correlations. Bull postweaning gain was associated with intermuscular (-0.24 to -0.35), body cavity (-0.24 to -0.29), and marbling fat (-0.24 to -0.39) in steers. Bull hip height was associated with body cavity (-0.20 to -0.29) and marbling fat (-0.20 to -0.47) in steers. Bull ultrasound fat depth was associated with subcutaneous (0.11 to 0.29), intermuscular (0.05 to 0.36), body cavity (0.27 to 0.49), and marbling fat (0.27 to 0.73) in steers. Bull ultrasound intramuscular fat percentage was associated with subcutaneous (-0.22 to -0.44) and intermuscular fat (-0.06 to 0.31) in steers. Bull ultrasound LM area was associated with body cavity (-0.25 to -0.31) and marbling fat (-0.25 to -0.30) in steers. Ultrasound LM width measurements were negatively correlated with subcutaneous fat (rg = -0.09 to -0.18), intermuscular fat (rg = -0.53 to -0.61), body cavity fat (rg = -0.63 to -0.69), and marbling score (rg = -0.75 to -0.87) at slaughter age-, HCW-, and fat depth-constant endpoints; correlations were generally lower at a marbling score-constant end point (rg = 0.07 to -0.49). Ultrasound indicator traits measured in seedstock may be useful in altering fat partitioning in commercial beef carcasses.
利用1031头育成杂交肉牛的部分胴体解剖数据，计算皮下、肌间和体腔脂肪百分比以及调整至屠宰年龄、热胴体重、脂肪厚度和大理石花纹评分恒定终点的大理石花纹评分之间的遗传力和遗传相关性。还计算了这些脂肪分区与一岁肉牛公牛（n = 2172）评估的活体生长和超声性状以及阉牛胴体测量值之间的遗传相关性。不同脂肪分区的遗传力范围为0.22（大理石花纹评分恒定的体腔脂肪）至0.46（热胴体重恒定的大理石花纹评分）。皮下脂肪与肌间脂肪之间的遗传相关性（rg = 0.16至0.32）以及肌间脂肪与体腔脂肪之间的遗传相关性（rg = 0.38至0.50）比皮下脂肪与体腔脂肪之间的遗传相关性（rg = -0.08至0.05）更高，表明脂肪库并非受相同的遗传控制。将脂肪库调整至不同终点会影响遗传相关性的大小，但通常不会改变其符号。公牛断奶后增重与阉牛的肌间脂肪（-0.24至-0.35）、体腔脂肪（-0.24至-0.29）和大理石花纹脂肪（-0.24至-0.39）相关。公牛髋高与阉牛的体腔脂肪（-0.20至-0.29）和大理石花纹脂肪（-0.20至-0.47）相关。公牛超声脂肪厚度与阉牛的皮下脂肪（0.11至0.29）、肌间脂肪（0.05至0.36）、体腔脂肪（0.27至0.49）和大理石花纹脂肪（0.27至0.73）相关。公牛超声肌内脂肪百分比与阉牛的皮下脂肪（-0.22至-0.44）和肌间脂肪（-0.06至0.31）相关。公牛超声背最长肌面积与阉牛的体腔脂肪（-0.25至-0.31）和大理石花纹脂肪（-0.25至-0.30）相关。在屠宰年龄、热胴体重和脂肪厚度恒定终点时，超声背最长肌宽度测量值与皮下脂肪（rg = -0.09至-0.18）、肌间脂肪（rg = -0.53至-0.61）、体腔脂肪（rg = -0.63至-0.69）和大理石花纹评分（rg = -0.75至-0.87）呈负相关；在大理石花纹评分恒定终点时，相关性通常较低（rg = 0.07至-0.49）。在种畜中测量的超声指标性状可能有助于改变商业牛肉胴体的脂肪分布。
