Geary T W, McFadin E L, MacNeil M D, Grings E E, Short R E, Funston R N, Keisler D H
USDA-ARS, Fort Keogh Livestock and Range Research Laboratory, Miles City, MT 59301, USA.
J Anim Sci. 2003 Jan;81(1):1-8. doi: 10.2527/2003.8111.
Our objective was to determine if serum concentrations of leptin could be used to predict carcass composition and merit in feedlot finished cattle. Two different groups of crossbred Bos taurus steers and heifers were managed under feedlot conditions near Miles City, MT. The first group consisted of 88 1/2 Red Angus, 1/4 Charolais, and 1/4 Tarentaise composite gene combination steers (CGC) harvested at the ConAgra processing facility in Greeley, CO. The second group (Lean Beef Project; LB) consisted of 91 F2 steers and heifers born to Limousin, Hereford, or Piedmontese by CGC F1 cows crossed to F1 bulls of similar breed composition and harvested at a local processing facility in Miles City, MT. Blood samples were collected approximately 24 h before harvest (CGC) or approximately 3 d before and at harvest (LB). No differences in serum concentrations of leptin were detected (P > 0.10) between Hereford, Limousin, or Piedmontese F2 calves nor between LB steers and heifers. Positive correlations (P < 0.01) existed between serum leptin and marbling score (r = 0.35 and 0.50), fat depth measured between the 12th and 13th rib (r = 0.34 and 0.46), kidney, pelvic, and heart fat (KPH) (r = 0.42 and 0.46), and quality grade (r = 0.36 and 0.49) in CGC and LB cattle, respectively. Serum leptin was also positively correlated with calculated yield grade for CGC steers (r = 0. 19; P = 0. 10) and LB cattle (r = 0.52; P < 0.01). Longissimus area was not correlated with serum leptin in CGC steers (r = 0.12; P > 0.10). However, a negative correlation existed between longissimus area and serum leptin in the LB cattle (r = -0.45; P < 0.01). Serum concentrations of leptin were significantly associated with carcass composition (marbling, back fat depth, and KPH fat) and quality grade in both groups of cattle studied and may provide an additional indicator of fat content in feedlot cattle.
我们的目标是确定血清瘦素浓度是否可用于预测育肥牛的胴体组成和品质。两组不同的杂交牛（Bos taurus）阉公牛和小母牛在蒙大拿州迈尔斯城附近的饲养场条件下饲养。第一组由88头1/2红安格斯、1/4夏洛来和1/4塔朗泰斯复合基因组合阉公牛（CGC）组成，在科罗拉多州格里利的康尼格拉加工设施屠宰。第二组（瘦肉牛肉项目；LB）由91头F2阉公牛和小母牛组成，它们由CGC F1母牛与利木赞、赫里福德或皮埃蒙特种公牛杂交产下，这些母牛和公牛的品种组成相似，在蒙大拿州迈尔斯城的当地加工设施屠宰。在屠宰前约24小时（CGC）或屠宰前约3天及屠宰时（LB）采集血样。在赫里福德、利木赞或皮埃蒙特F2犊牛之间，以及LB阉公牛和小母牛之间，未检测到血清瘦素浓度的差异（P>0.10）。血清瘦素与大理石花纹评分（r=0.35和0.50）、第12和13肋骨间的脂肪厚度（r=0.34和0.46）、肾、盆腔和心脏脂肪（KPH）（r=0.42和0.46）以及CGC和LB牛的质量等级（r=0.36和0.49）之间存在正相关（P<0.01）。血清瘦素与CGC阉公牛（r=0.19；P=0.10）和LB牛（r=0.52；P<0.01）的计算产量等级也呈正相关。CGC阉公牛的背最长肌面积与血清瘦素不相关（r=0.12；P>0.10）。然而，LB牛的背最长肌面积与血清瘦素呈负相关（r=-0.45；P<0.01）。在所研究的两组牛中，血清瘦素浓度与胴体组成（大理石花纹、背部脂肪厚度和KPH脂肪）和质量等级显著相关，可能为育肥牛的脂肪含量提供一个额外的指标。
