Zhai Hengxiao, Adeola Olayiwola, Liu Jingbo
Southwest University of Science and Technology, Mianyang, China.
DSM China Animal Nutrition Research Center, Bazhou, China.
Anim Nutr. 2022 Apr 2;9:127-137. doi: 10.1016/j.aninu.2022.01.010. eCollection 2022 Jun.
Phosphorus (P) is an essential nutrient for diverse biological processes, which aggregate to the animal's requirement for P, and nutritionists strive to meet this requirement accurately. The P demand for a growing pig comprises requirements for maintenance and tissue deposition. The P in feed ingredients, however, must be digested and absorbed before its ultimate partition between the 2 aforementioned requirement components. Phosphorus from various sources could behave differently during digestion and absorption, which results in their disparate bioavailability for pigs. The system of standardized total tract digestibility reflects true total tract digestibility of P and feed ingredient effects on specific endogenous P loss with relative ease of implementation, and this system guarantees satisfactory additivity in digestible P among the ingredients in a diet-the foundation for diet formulation. The basal endogenous P loss, which is much easier to measure than the specific endogenous P loss, is considered as part of the pig's maintenance requirement. With this arrangement, a digestibility framework is established both for measuring the P-providing capacity of various feed ingredients and for describing the pig's P requirement. This framework entails basic understanding of the function, digestion, absorption, excretion, and homeostasis of P as support pillars. Understanding the workings of this framework enables potential integration of factors such as environment conditions and disease status in future P requirement models. The current review discusses dietary sources, digestion, absorption, bioavailability and requirement of P for growing pigs to understand the status quo, revealing the points of consensus as well as those of debate, and to encourage further investigation to provide more clarity.
磷（P）是多种生物过程所必需的营养素，这些过程共同构成了动物对磷的需求，营养学家努力准确满足这一需求。生长猪对磷的需求包括维持需求和组织沉积需求。然而，饲料原料中的磷必须先经过消化和吸收，才能最终在上述两种需求成分之间进行分配。不同来源的磷在消化和吸收过程中的表现可能不同，这导致它们对猪的生物利用率存在差异。标准化全肠道消化率系统相对容易实施，能够反映磷的真实全肠道消化率以及饲料原料对特定内源磷损失的影响，并且该系统保证了日粮中各成分可消化磷的满意加和性——这是日粮配方的基础。基础内源磷损失比特定内源磷损失更容易测量，被视为猪维持需求的一部分。通过这种安排，建立了一个消化率框架，用于衡量各种饲料原料的磷供应能力以及描述猪的磷需求。这个框架需要对磷的功能、消化、吸收、排泄和体内平衡有基本的了解作为支撑。了解这个框架的运作方式有助于在未来的磷需求模型中潜在地整合环境条件和疾病状态等因素。本综述讨论了生长猪磷的日粮来源、消化、吸收、生物利用率和需求，以了解现状，揭示共识点和争议点，并鼓励进一步研究以提供更多的清晰度。
