Department of Animal Science, Iowa State University, Ames 50011.
School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson 85721.
J Dairy Sci. 2017 Dec;100(12):10353-10366. doi: 10.3168/jds.2017-13242.
We have seen remarkable advances in animal productivity in the last 75 years, with annual milk yield per cow increasing over 4-fold and no evidence of nearing a plateau. Because of these gains in productive efficiency, there have been dramatic reductions in resource inputs and the carbon footprint per unit of milk produced. The primary source for the historic gains relates to animal variation in nutrient partitioning. The regulation of nutrient use for productive functions has the overall goal of maintaining the cow's well-being regardless of the physiological or environmental challenges. From a conceptual standpoint, it involves both acute homeostatic controls operating on a minute-by-minute basis and chronic homeorhetic controls operating on a long-term basis to provide orchestrated adaptations that coordinate tissues and body processes. This endocrine regulation is mediated by changes in circulating anabolic and catabolic hormones, hormone membrane receptors and intracellular signaling pathways. The coordination of tissues and physiological systems includes a plethora of hormones, but insulin and somatotropin are 2 key regulators of nutrient trafficking. Herein, we review the advances in our understanding of both conceptual and actual regulation of nutrient partitioning in support of milk synthesis and identify examples of the challenges and future opportunities in dairy science.
在过去的 75 年中，我们见证了动物生产力的显著进步，奶牛的年产奶量增加了超过 4 倍，而且没有迹象表明已经接近高原。由于生产效率的提高，资源投入和每单位牛奶生产的碳足迹大幅减少。这些历史性进展的主要原因与动物在营养分配方面的差异有关。营养物质用于生产功能的调节的总体目标是无论生理或环境挑战如何，都要维持奶牛的健康。从概念上讲，它既涉及每分钟进行的急性体内平衡控制，也涉及长期进行的慢性同型调节，以提供协调的适应，协调组织和身体过程。这种内分泌调节是通过循环中的合成代谢和分解代谢激素、激素膜受体和细胞内信号通路的变化来介导的。组织和生理系统的协调包括大量的激素，但胰岛素和生长激素是营养物质运输的 2 个关键调节剂。在此，我们回顾了对支持牛奶合成的营养分配的概念和实际调节的理解进展，并确定了奶牛科学面临的挑战和未来机遇的实例。
