Toward precision feeding in pig production: optimal phosphorus and calcium dietary levels

动物生产的成功和可持续性面临着许多挑战，如饲养成本的不断增加，公众对农业影响的日益关注，以及有效的养分回收以尽量减少对环境的破坏。鉴于磷(P)既是肥料又是污染物，如果过量存在，了解如何最大限度地在动物饲料中使用它，以优化健康，最大限度地减少损失，从而减少对环境的影响是很重要的。因此，提高猪对磷的利用效率至关重要。在规定的时间内对畜群中的所有动物提供单一饲料，并在最大限度地提高牲畜生产性能的水平上提供膳食磷的做法已成为许多研究的主题。提高猪总磷利用率的最佳途径是每天提供每头猪的确切需要量。这可以通过监测采食量和生长个体模式的精确饲养来实现。生产成本最多可降低4%，磷排泄量可降低30%以上，这将大大提高生猪生产的可持续性。然而，在猪的情况下，精确喂养代表了一种范式转变和相当大的挑战，其中矿物质如钙（Ca）和磷与生理状态有强烈的相互作用。针对多种反应标准（如生长性能、骨矿化、磷排泄）和生产目标（如盈利能力、动物福利、环境），难以确定精确饲养饲粮中的最佳矿物质水平。***本研究项目的总体目标是在本人目前磷和钙代谢研究成果的基础上，通过使用精密日粮配制的饲料，结合个体猪钙和磷需要量的实时估算，开展基础研究，优化猪对磷的利用。我打算分两步实现这一目标：1 .通过动物实验增加对猪磷和钙代谢的基本认识；2 .将新知识整合到目前开发的模型中，利用模型设计喂养策略，测试策略并相应地调整模型。

Animal productions are facing many challenges for their successfulness and sustainability such as the constant increases in feeding cost, the growing public opinion about the impact of agriculture, and effective nutrient recycling to minimize environmental damages. Given that the phosphorus (P) both a fertilizer and a pollutant if present in excess, it is important to understand how to maximise its use in animal feed to optimize health and minimise losses and so, the environmental impact. Improving the efficiency of P use by pigs is therefore essential. The practices of providing a single feed to all animals in the herd over prescribed periods of time and providing dietary P at levels intended to maximize livestock performance have been the subject of numerous studies. The best way to improve overall P utilization by pigs would be to provide the exact requirement of each animal on a daily basis. This can be achieved by precision feeding which monitoring individual patterns of feed intake and growth. Production costs can be reduced by up to 4 % and P excretion by more than 30 %, which would increase considerably the sustainability of hog production. However, precision feeding represents a paradigm shift and a considerable challenge in the case of swine, in which minerals such as calcium (Ca) and P interact strongly with physiological status. Optimal mineral levels in diets formulated for precision feeding are difficult to establish for multiple response criteria (e.g. growth performance, bone mineralization, P excretion) and production objectives (e.g. profitability, animal welfare, environment). ***The general goal of this research program is to pursue basic research to optimize P utilization by pigs through the use of feeds formulated for precision diets in conjunction with real-time estimation of Ca and P requirements of individual pigs, based on the findings of my P and Ca metabolism research so far. I intend to achieve this in two steps: 1- increase fundamental understanding of porcine metabolism of P and Ca through animal experiments, and 2- integrate the new knowledge into the model developed so far, use the model to design feeding strategies, test the strategies and adjust the model accordingly.