Wiseman T G, Mahan D C, Moeller S J, Peters J C, Fastinger N D, Ching S, Kim Y Y
The Ohio State University and The Ohio Agricultural Research and Development Center, Columbus, OH 43210-1095, USA.
J Anim Sci. 2007 Jul;85(7):1816-24. doi: 10.2527/jas.2006-406. Epub 2007 Mar 30.
Two genetic lines with different lean gains were evaluated for various body measurements and indices of lean tissue in barrows and gilts from 20 to 125 kg of BW. One genetic line was identified as the low-lean line [280 g of fat-free lean (FFL)/d], and the second line was the high-lean line (375 FFL gained/d). The experiment was conducted as a completely randomized design using a 2 x 2 x 5 factorial arrangement of treatments in 6 replicates (n = 120 pigs). The 2 genetic lines and sexes were provided ad libitum access to cornsoybean mixtures that met or exceeded their required amino acid requirements for their respective lean gain potentials. Six pigs of each sex and genetic line were slaughtered initially and at 25-kg of BW intervals to 125 kg of BW. Pigs slaughtered were measured for height, width, and length using metal calipers. Backfat and LM area were measured using real-time ultrasound, with backfat depth also measured using A-mode ultrasound technology. Longissimus muscle area and back-fat thickness at the 10th rib were measured on the chilled carcass. Data was analyzed using the MIXED procedure of SAS, with the animal as the experimental unit. Shoulders (P < 0.05) and lumbars (P < 0.05) were wider in the low-lean genetic line and in barrows. Gilts and the high-lean genetic line had less backfat and greater LM areas than the low-lean genetic line. As BW increased, there was a greater increase in FFL tissue and lower backfat depths in the high-lean vs. the low-lean genetic line. This resulted in a greater divergence of measurement values as BW increased. Femur weight, length, and cortical wall thickness were greater in the high-lean genetic line, but the differences were not significant. The high-lean genetic line had a greater (P < 0.01) organic matrix content in the femur and less ash, resulting in a lower percentage of bone ash (P < 0.01). The results indicate that differences occurred phenotypically between pigs having more muscle (wider hams) or more fat (wider shoulder and lumbar). As BW increased, the high-lean pigs had an increase in lean tissue, particularly after 75 kg of BW, and less backfat and less bone mineralization, whereas the low-lean line pigs had increased backfat and greater bone mineralization. Real-time ultrasound measurements using various formulas to estimate lean tissue produced values close to those determined from carcass measurements at 100 and 125 kg of BW.
对两个瘦肉生长速度不同的遗传品系进行了评估，测量了体重在20至125千克的公猪和母猪的各种身体指标以及瘦肉组织指数。一个遗传品系被确定为低瘦肉品系[每日无脂瘦肉（FFL）增重280克]，另一个品系为高瘦肉品系（每日FFL增重375克）。试验采用完全随机设计，处理采用2×2×5析因排列，共6个重复（n = 120头猪）。两个遗传品系和性别均可自由采食满足或超过其各自瘦肉生长潜力所需氨基酸要求的玉米 - 大豆混合料。每个性别和遗传品系的6头猪在初始体重以及体重每隔25千克直至125千克时进行屠宰。对屠宰的猪使用金属卡尺测量其身高、体宽和体长。使用实时超声测量背膘厚度和腰大肌面积，背膘深度也使用A模式超声技术测量。在冷却胴体上测量第10肋骨处的腰大肌面积和背膘厚度。数据采用SAS的MIXED过程进行分析，以个体作为实验单位。低瘦肉遗传品系和公猪的肩部（P < 0.05）和腰部（P < 0.05）更宽。与低瘦肉遗传品系相比，母猪和高瘦肉遗传品系的背膘更少，腰大肌面积更大。随着体重增加，高瘦肉遗传品系的FFL组织增加幅度更大，背膘深度更低，而低瘦肉遗传品系则相反。这导致随着体重增加测量值的差异更大。高瘦肉遗传品系的股骨重量、长度和皮质骨壁厚更大，但差异不显著。高瘦肉遗传品系的股骨有机基质含量更高（P < 0.01），灰分更少，导致骨灰百分比更低（P < 0.01）。结果表明，肌肉较多（后腿更宽）或脂肪较多（肩部和腰部更宽）的猪在表型上存在差异。随着体重增加，高瘦肉猪的瘦肉组织增加，特别是在体重75千克之后，背膘更少，骨矿化程度更低，而低瘦肉品系猪的背膘增加，骨矿化程度更高。使用各种公式通过实时超声测量来估计瘦肉组织，所得值与体重100千克和125千克时胴体测量确定的值接近。
