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The improvements in growth, bone mineral status and nutrient digestibility in pigs following the addition of phytase is accompanied by modifications in ileal nutrient transporters
Phytase improves growth performance, nutrient digestibility and bone structure in pigs. However, little is known about its effect on ileal nutrient transporter gene expression. Prior to the start of the experiment all pigs were allowed an adaption period of 14 days and were fed a standard weaning diet. Forty-eight weaner pigs (11.75kg, sem 0.75) were randomly assigned to one of three experimental diets for a period of 44 days to measure growth performance. Following this 6 animals per treatment were randomly selected and slaughtered to measure the coefficient of apparent ileal nutrient digestibility (CAID), coefficient of apparent total tract nutrient digestibility (CATTD) and ileal nutrient transporter gene expression. The experimental treatments were as follows, 1) a high phosphorus (HP) diet containing 5.9 g/kg total P (tP), 3.2 g/kg available P (aP) and 6.8 g/kg calcium (Ca), 2) a low phosphorus (LP) diet containing 4.5 g/kg (tP), 1.8 g/kg aP and 5.2 g/kg Ca and 3) a phytase (PHY) diet containing the LP diet + 1000 FTU/kg of phytase. The addition of PHY increased ADG (700 g/day vs. 610 g/day sem 0.02; P<0.05), final BW (43kg vs. 37kg sem 1.02; P<0.01) and decreased FCR (1.74 vs. 2.05 sem 0.09; P<0.05) compared with the LP diet. Pigs offered the PHY diet had higher CAID of gross energy (748g/kg vs. 699g/kg vs. 700g/kg, sem 7.0; P<0.001) compared to the HP and LP diets respectively. Pigs offered the PHY diet had a higher CAID of nitrogen (716 g/kg vs. 669g/kg sem 14.3; P<0.05) compared to the HP diet. The addition of PHY improved the CATTD of Ca (766 g/kg vs. 487 g/kg vs. 451g/kg sem 42.96; P <0.001) and P (558g/kg vs. 220g/kg vs. 389g/kg sem 43.12; P < 0.001) compared to both LP and HP respectively. The PHY diet had increased gene expression of PEPT1 (1.40 vs. 0.47 sem 0.29, P<0.05) and a tendency towards increased gene expression of FABP2 (1.67 vs. 0.73 sem 0.37 P<0.10) compared to the LP diet. The LP diet had lower gene expression of SGLT1 (1.32 vs. 0.51 sem 0.31) and GLUT2 (0.26 vs. 1.26 sem 0.29) (P<0.05) compared to the HP diet. In summary, offering a diet supplemented with PHY improves growth performance and ileal and nutrient digestibility. PHY addition increases the gene expression of the peptide transporter PEPT1 and tended to increase the fatty acid transporter FABP2.
Keywords: Phytase: Nutrient Transporter Gene Expression: Pigs