The effects of concurrent increases in supplementation of calcium and phytase on growth performance, balance of Ca and P, and bone mineralization in nursery pigs

Abstract

The objective of this study was to investigate the effects of concomitantly increasing supplementation of Ca and phytase on growth performance, balance of Ca and P, and bone mineralization in nursery pigs. There were 8 experimental diets. The positive control (PC) 1 and 2 were formulated to contain 0.64 and 0.85% total Ca, respectively, whereas the dietary concentrations of other nutrients were identical and adequate. The negative control (NC) was deficient in total Ca (0.48%) and total P (0.41%). Five combinations of incremental levels of Ca and phytase [0.48% and 1,750 phytase units (FYT)/kg, 0.52% and 2,000 FYT/kg, 0.55% and 2,250 FYT/kg, 0.59% and 2,600 FYT/kg, and 0.63% and 3,000 FYT/kg] were added to the NC to establish the remaining 5 experimental diets. Each diet was fed to 6 pens of 6 pigs (3 barrows and 3 gilts per pen). All diets contained 3 g/kg TiO2, and fecal samples were collected from each pen during the trial. At the end, one pig per pen was euthanized to collect the right tibia and urine in bladder. The results showed that the pigs of NC gained less weight, consumed less feed, and utilized feed less efficiently than their counterparts fed the PC and the treatments with phytase (P < 0.01). With increasing supplementation of Ca and phytase, there was a tendency for gain:feed to decrease (P < 0.10). There was a significant reduction in bone dry weight; and in percentages as well as weights of bone ash, Ca and P; in pigs of NC compared with pigs of PC1, PC2, or phytase treatments. In comparison to PC2, PC1 and phytase treatments resulted in a higher percentage of bone P and greater weights of bone ash, Ca and P (P < 0.05). There was no significant effect of concurrent supplementation of Ca and phytase on bone mineralization. The NC had significantly lower apparent total tract digestibility (ATTD) of Ca and P, lower concentrations of digestible Ca and P, but a higher ATTD Ca/ATTD P ratio than PC1, PC2 or the phytase treatments. The averages of ATTD of Ca and P in treatments with phytase were significantly higher than PC1 or PC2 (P < 0.01). With increasing addition of Ca and phytase, the ATTD of P, digestible Ca, and P, and the ATTD Ca/ATTD P ratio increased linearly (P < 0.05), which contrasted with a linear reduction in ATTD of Ca (P < 0.05). Meanwhile, there was a linear (P < 0.01) increase in the concentration of urinary Ca. In conclusion, increasing the dietary supplementation of phytase in conjunction with the increasing dietary Ca level increased the dietary ATTD Ca/ATTD P ratio without damaging the absorption of P in the current study. The higher ATTD Ca/ATTD P ratio did not improve the bone mineralization markedly and thus the extra Ca was voided through urine.

A New Biosynthetic 6-Phytase Added at 500 Phytase Unit/kg Diet Improves Growth Performance, Bone Mineralization, and Nutrient Digestibility and Retention in Weaned Piglets and Growing–Finishing Pigs

“…In fact, P is an indispensable nutrient needed for normal growth, and it plays important roles in vital functions, such as energy and amino acid metabolism, protein synthesis, and maintaining acid–base balance [ 27 , 28 , 29 , 30 ]. Several studies have reported improvements in performance when phytase was used in piglets and growing pigs [ 21 , 31 , 32 , 33 , 34 , 35 ]. In the current study, the addition of phytase at 500 FTU/kg diet improved the growth performance and feed efficiency of nursery and growing–finishing pigs fed diets reduced in digestible P and Ca.…”