Performance and carcass characteristics of lambs ½ Dorper + ½ Santa Inês, slaughtered with different thicknesses of subcutaneous fat

SUMMARY The aim of this study was to evaluate the effect of subcutaneous fat thickness (SFT) on slaughter in lambs ½ Dorper + ½ Santa Inês (DSI) on performance, carcass characteristics and commercial cuts. It was used twenty-four lambs, slaughtered with 2mm, 3mm and 4mm SFT. There was an effect of SFT on performance: for days of confinement (2mm = 51.38, 3mm = 66.50, 4mm = 91.63 days), age at slaughter (2mm = 139.38, 3mm = 159.88, 4mm = 171.00 days), final body weight (2mm = 33.50, 3mm = 42.81, 4mm = 46.19 kg), total weight gain (2mm = 18.75, 3mm = 25.08, 4mm = (2mm = 0.44, 3mm = 0.39, 4mm = 0.28kg), slaughter weight (2mm = 32.76, 3mm = 39.79, 4mm = 44.88 kg), body condition score (2mm = 2.97, 3mm = 3.13, 4mm = 3.56); for carcass characteristics: warm carcass weight (2mm = 15.33, 3mm = 19.16, 4mm = 21.90 kg) and cold (2mm = 15.03, 3mm = 18.75, 4mm = 21.47), cooling losses (2mm = 0.00234; 3mm = 0.00333; 4mm = 0.00201 kg), carcass yields: in the refrigerator (2mm=46,79; 3mm=48,30; 4mm=48,79%); commercial (2mm = 45.88, 3mm = 47.25, 4mm = 47.82%) and true (2mm = 52.93, 3mm = 54.51, 4mm = 55.67%); carcass compactness index (2mm= 0,250; 3mm=0,30; 4mm=0,33 kg/cm) for cut weights; neck (2mm=0,44; 3mm=0,55; 4mm=0,56 kg); palette (2mm=1,38; 3mm=1,61; 4mm=2,14 kg), flank steak (2mm=2,16; 3mm=2,73; 4mm=3,19 kg), loin (2mm=0,93; 3mm=1,14; 4mm=1,25 kg), and leg (2mm=2,68; 3mm=3,20, 4mm=3,76 kg). For the tissue composition of only the muscular cuts of the neck (2mm = 50.24, 3mm = 51.44, 4mm = 55.34%), bone of the neck (2mm = 30.24, 3mm = 29.63, 4mm = 25.91%), of the loin (2mm=15,05; 3mm=24,63; 4mm=24,71%) and the leg (2mm=11,38; 3mm=13,33; 4mm=13,13%), they presented differences between the SFT (p> 0.05). It is recommended to slaughter lambs ½ Dorper + ½ Santa Inês with 3mm of SFT.

研究概要
本研究旨在评估皮下脂肪厚度（subcutaneous fat thickness, SFT）对1/2杜泊羊（Dorper）+1/2圣塔伊内斯羊（Santa Inês，简称DSI）羔羊的屠宰性能、胴体特性及商业分割肉块品质的影响。试验共选取24只羔羊，按皮下脂肪厚度分为2mm、3mm、4mm三组开展屠宰试验。

结果表明，皮下脂肪厚度对多项性能指标均存在显著影响：圈养天数（2mm组为51.38天、3mm组为66.50天、4mm组为91.63天）、屠宰日龄（2mm组为139.38天、3mm组为159.88天、4mm组为171.00天）、终末体重（2mm组为33.50kg、3mm组为42.81kg、4mm组为46.19kg）、总增重（原文存在格式排版误差，2mm组为18.75、3mm组为25.08，4mm组对应数据标注为(2mm=0.44、3mm=0.39、4mm=0.28kg)）、屠宰体重（2mm组为32.76kg、3mm组为39.79kg、4mm组为44.88kg）、体况评分（2mm组为2.97、3mm组为3.13、4mm组为3.56）。

胴体特性维度：热胴体重（2mm组为15.33kg、3mm组为19.16kg、4mm组为21.90kg）、冷胴体重（2mm组为15.03kg、3mm组为18.75kg、4mm组为21.47kg）、冷却损耗（2mm组为0.00234kg、3mm组为0.00333kg、4mm组为0.00201kg）；胴体出肉率包含冷藏胴体出肉率（2mm组为46.79%、3mm组为48.30%、4mm组为48.79%）、商业分割肉块出肉率（2mm组为45.88%、3mm组为47.25%、4mm组为47.82%）及真实出肉率（2mm组为52.93%、3mm组为54.51%、4mm组为55.67%）；胴体紧凑指数（2mm组为0.250kg/cm、3mm组为0.30kg/cm、4mm组为0.33kg/cm）。

商业分割肉块重量方面：颈肉（2mm组为0.44kg、3mm组为0.55kg、4mm组为0.56kg）、肩胛肉块（2mm组为1.38kg、3mm组为1.61kg、4mm组为2.14kg）、腹胁排（2mm组为2.16kg、3mm组为2.73kg、4mm组为3.19kg）、腰肉（2mm组为0.93kg、3mm组为1.14kg、4mm组为1.25kg）及后腿肉（2mm组为2.68kg、3mm组为3.20kg、4mm组为3.76kg）。

针对颈部肌肉切块的组织组成：肌肉占比（2mm组为50.24%、3mm组为51.44%、4mm组为55.34%）、骨骼占比（2mm组为30.24%、3mm组为29.63%、4mm组为25.91%）；腰肉块骨骼占比（2mm组为15.05%、3mm组为24.63%、4mm组为24.71%）及后腿肉块骨骼占比（2mm组为11.38%、3mm组为13.33%、4mm组为13.13%），上述指标在不同皮下脂肪厚度组间差异均无统计学意义（p>0.05）。

综合试验结果，建议对1/2杜泊羊+1/2圣塔伊内斯羊羔羊采用3mm皮下脂肪厚度标准进行屠宰。