title: Meta-analysis of phosphorus utilization by growing pigs: effect of dietary phosphorus, calcium and exogenous phytase.
abstract: Optimizing phosphorus (P) utilization in pigs requires improving our capacity to predict the amount of P absorbed and retained, with the main modulating factors taken into account, as well as precisely determining the P requirements of the animals. Given the large amount of published data on P utilization in pigs, a meta-analysis was performed to quantify the impact of the different dietary P forms, calcium (Ca) and exogenous phytases on the digestive and metabolic utilization criteria for dietary P in growing pigs. Accordingly, the amount of phytate P (PP) leading to digestible P (g/kg) was estimated to be 21%, compared with 73% for non-phytate P (NPP) from plant ingredients and 80% for NPP from mineral and animal ingredients (P < 0.001). The increase in total digestible dietary P following the addition of microbial phytase (PhytM) from Aspergillus niger (P < 0.001) was curvilinear and about two times higher than the increase following the addition of plant phytase, which leads to a linear response (P < 0.001). The response of digestible P to PhytM also depends on the amount of substrate, PP (PhytM(2) × PP, P < 0.001). The digestibility of dietary P decreased with dietary Ca concentration (P < 0.01) independently of phytase but increased with body weight (BW, P < 0.05). Although total digestible dietary P increased linearly with total NPP concentration (P < 0.001), retained P (g/kg), average daily gain (ADG, g/day) and average daily feed intake (ADFI, g/day) increased curvilinearly (P < 0.001). Interestingly, whereas dietary Ca negatively affected P digestibility, the effect of dietary Ca on retained P, ADG and ADFI depended on total dietary NPP (NPP × Ca, P < 0.01, P < 0.05 and P < 0.01, respectively). Increasing dietary Ca reduced retained P, ADG and ADFI at low NPP levels, but at higher NPP concentrations it had no effect on ADG and ADFI despite a positive effect on retained P. Although the curvilinear effect of PhytM on digestible P increased with PP (P < 0.001), this effect was lessened by total NPP for ADG and ADFI (PhytM × NPP and PhytM(2) × NPP, P < 0.05) and depended on both total NPP and Ca for retained P (PhytM(2) × NPP × Ca, P < 0.01). This meta-analysis improves our understanding of P utilization, with major modulating factors taken into account. The information generated will be useful for the development of robust models to formulate environmentally friendly diets for growing pigs.
authors.affiliation: Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Sherbrooke, Quebec, Canada.
authors.forename: M P
authors.initials: MP
authors.lastname: Létourneau-Montminy
authors.forename: C
authors.initials: C
authors.lastname: Jondreville
authors.forename: D
authors.initials: D
authors.lastname: Sauvant
authors.forename: A
authors.initials: A
authors.lastname: Narcy
mesh_terms: D010832:6-Phytase / Q000378:metabolism*; D000821:Animal Feed / Q000032:analysis; D000822:Animal Husbandry; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002136:Calcium, Dietary / Q000378:metabolism*; D004063:Digestion; D016226:Phosphorus, Dietary / Q000378:metabolism*; D013552:Swine / Q000254:growth & development / Q000502:physiology*
chemical_list: D002136:Calcium, Dietary; D016226:Phosphorus, Dietary; D010832:6-Phytase