Understanding biological mechanisms influencing feed efficiency in beef cattle: insulin resistance

了解影响肉牛饲料效率的生物机制：胰岛素抵抗

• 批准号: RGPIN-2018-04217
• 负责人: Wood, Katharine
• 金额: $ 2.48万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=712780
• 关键词: Understanding; biological; mechanisms; influencing; feed

In beef production, feed represents a major production cost. Although considerable research has been invested in improving feed efficiency in beef cattle, many of the underlying biological mechanisms influencing animal variability are not well understood in beef cattle. Insulin resistance has been observed in cattle and sheep, however the relationship to feed efficiency in beef cattle is uncharacterized. My overall hypothesis is that animal variability in feed efficiency is partially related to animal differences in insulin responsiveness. The specific objectives which will be addressed in this Discovery grant are to 1) To characterize relationships between insulin resistance [indicated by glucose tolerance test (GTT) in cattle and hyperinsulinaemic-euglycemic clamp (HEC) in sheep] and measures of growth performance and feed efficiency in finishing steers and lambs, and identify metabolic markers associated with insulin resistance and feed efficiency (adipokines/inflammatory response, lypolisis/lipogenesis, energy signaling) in muscle and hepatic tissue and pancreas cell morphology, 2) Evaluate indices of insulin resistance in reference to GTT and identify an index that best predicts insulin resistance for use when intensive sampling is not possible, and to develop mathematical models to predict efficiency classification early in the feeding period, and 3) To determine if improvement in insulin resistance will improve feed efficiency. To address this hypothesis a series of animal experiments will be conducted. The proposed research will utilize in vivo (performance trials, GTT, HEC) and western blotting, to evaluate relationships between whole body measures of insulin sensitivity and associated metabolic markers of energy metabolism, lipolysis/lipogenesis and leptin, inflammatory response in hepatic and muscle tissues, and measures of feed efficiency (feed intake, residual feed intake and feed conversion ratio). Accompanying work will evaluate various available models to indicate insulin resistance in beef cattle and suggest a method that may be useful for identification of insulin resistance in steers where intensive sampling is not possible. Additionally, this work will provide training for one MSc, one PhD, and two undergraduate students. This research will provide a novel understanding of the role of insulin resistance and feed efficiency in ruminants, and will deepen the understanding of biological mechanisms influencing feed efficiency as a whole.

在牛肉生产中，饲料是主要的生产成本。尽管在提高肉牛饲料效率方面进行了大量研究，但影响肉牛动物变异性的许多潜在生物学机制尚未得到很好的理解。在牛和羊中已观察到胰岛素抵抗，但其与肉牛饲料效率的关系尚不清楚。我的总体假设是，动物饲料效率的差异部分与动物胰岛素反应性的差异有关。该发现基金将解决的具体目标是：1)表征胰岛素抵抗[由牛的葡萄糖耐量试验（GTT）和绵羊的高胰岛素-正糖抑制试验（HEC）表明]与肥育牛和羔羊的生长性能和饲料效率之间的关系，并确定与胰岛素抵抗和饲料效率相关的代谢标志物(脂肪因子/炎症反应、溶解/脂肪生成、2)参考GTT评估胰岛素抵抗指标，并确定一个最能预测胰岛素抵抗的指标，以便在无法进行密集采样的情况下使用，并建立数学模型，以便在摄食期早期预测效率分类。3)确定胰岛素抵抗的改善是否会提高饲料效率。为了验证这一假设，将进行一系列的动物实验。该研究将利用体内试验（性能试验、GTT、HEC）和免疫印迹法，评估全身胰岛素敏感性指标与能量代谢、脂肪分解/脂肪生成和瘦素相关代谢指标、肝脏和肌肉组织炎症反应以及饲料效率指标（采食量、剩余采食量和饲料转化率）之间的关系。随后的工作将评估各种可用的模型，以表明肉牛的胰岛素抵抗，并提出一种方法，可用于在不可能进行密集采样的情况下鉴定肉牛的胰岛素抵抗。此外，这项工作将为1名硕士，1名博士和2名本科生提供培训。本研究将为反刍动物胰岛素抵抗与饲料效率的关系提供新的认识，并将从整体上加深对影响饲料效率的生物学机制的认识。