Dietary Phosphorus and Calcium Utilization in Growing Pigs: Requirements and Improvements

Abstract

The sustainability of animal production relies on the judicious use of phosphorus (P). Phosphate, the mined source of agricultural phosphorus supplements, is a non-renewable resource, but phosphorus is essential for animal growth, health, and well-being. P must be provided by efficient and sustainable means that minimize the phosphorus footprint of livestock production by developing precise assessment of the bioavailability of dietary P using robust models. About 60% of the phosphorus in an animal's body occurs in bone at a fixed ratio with calcium (Ca) and the rest is found in muscle. The P and Ca requirements must be estimated together; they cannot be dissociated. While precise assessment of P and Ca requirements is important for animal well-being, it can also help to mitigate the environmental effects of pig farming. These strategies refer to multicriteria approaches of modeling, efficient use of the new generations of phytase, depletion and repletion strategies to prime the animal to be more efficient, and finally combining these strategies into a precision feeding model that provides daily tailored diets for individuals. The industry will need to use strategies such as these to ensure a sustainable plant-animal-soil system and an efficient P cycle.

Keywords: calcium; environment; mitigation; phosphorus; requirements; swine.

Figure 1

(A) Structure of phytic acid at neutral pH (14); (B) phytate chelate with different cations. (14).

Figure 2

Evolution of protein and bone mineral content deposit as a function of average weight (89).

Figure 3

General layout of the proposed mechanistic model predicting total calcium (Ca) and apparent and standardized digestible phosphorus (ATTD and STTD P) requirements of growing pigs (12).

Figure 4

Effect of pH on phytase activity of the phytase products used in the in vitro degradation model with EC1: Quantum (AB Vista), EC2: Quantum Blue (AB Vista), EC3: Phyzyme XP (Danisco), CB: Ronozyme Hiphos (DSM), PL: Ronozyme NP (DSM), AN: Natuphos (BASF), BSP: AxtraPHY (Danisco). Reprinted with permission from (105). Copyright 2015 American Chemical Society.

Figure 5

Residual phytase activity of E. coli and P. lycii phytase after pepsin or gastric crude extract from trout stomach hydrolysis throughout incubation time (0, 60, 120, 180, and 240 min). The incubation was performed by adding 1 FTU phytase to a protease solution with 5000 U from porcine pepsin or gastric crude extract from fish, performed at pH 2.0 (HCl), 16 °C. The results are plotted as the mean ± SE (triplicates). Different letters, for each time, indicate significant differences (P<0.05) between phytases (106).

Figure 6

Theoretical relationship between P release from phytate and associated Ca value showing disproportionate extra phosphoric effect with initial destruction of the higher esters (103).

Figure 7

Hormonal regulation of phosphocalcic metabolism.

Figure 8

Body bone mineral content of growing pigs feeding depletion–repletion diets (145).