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，例如饲养成本的不断增加，公众对农业影响的看法越来越多，以及有效的营养循环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利用其在动物饲料中的作用以优化健康并最大限度地减少损失以及环境影响是很重要的。因此，提高猪对磷的利用效率至关重要。在规定的时间内为牛群中的所有动物提供单一饲料，并提供旨在最大限度地提高牲畜性能的饲料磷水平的做法一直是许多研究的主题。提高猪对磷的总利用率的最佳方法是提供每头猪每天的确切需要量。这可以通过精确喂养来实现，监测个体的摄食和生长模式。生产成本可降低4%，P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，精确饲喂代表了一种范式转变，对猪来说是一个相当大的挑战，因为钙（Ca）和磷等矿物质与生理状态有很强的相互作用。针对多个响应标准（例如生长性能、骨矿化、P排泄）和生产目标（例如盈利能力、动物福利、环境），难以确定为精确饲喂配制的日粮中的最佳矿物质水平。

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).