Effect of phytase supplementation to a high- and a low-phytate diet for growing pigs on the utilization of phosphorus and calcium

The effect on the utilization of P and Ca of phytase supplementation to a high- and low-phytate diet for growing pigs fitted with a simple T-cannula at the distal ileum, was determined. Eight barrows, 40.6 +/- 1.7kg BW, were assigned to four dietary treatments according to a repeated 4x4 Latin square design (n=8). Diets were: 1) a high-phytate diet containing 20% rice bran, a rich source of phytate-P; 2) diet 1 supplemented with 2000 phytase units (FTU) per kg; 3) a low-phytate diet containing 2% rice bran; and 4) diet 3 but supplemented with 2000 FTU per kg. Other major diet ingredients were barley, wheat, soybean meal and canola meal, and chromic oxide was added as an inert marker. For high- and low-phytate diets the contents were, respectively, 0.77 and 0.51% total P, 0.48 and 0.22% phytate-P and 1.30 and 0.86% Ca, while available P contents in all diets were similar (0.23%). Feces and urine collections started at 08:00 on day 8 of each 14-day experimental period and continued for 96h. Real digesta were collected from 08:00 to 20:00 on days 12-14. The diets were fed at 2.4xME maintenance requirement according to 1998 NRC standards. Meal allowances of equal amounts were offered twice daily at 08:00 and 20:00. Phytase supplementation improved (P < 0.05) the apparent total tract digestibilities and the amount of P and Ca retained. The improvement in P utilization was independent (P > 0.10) of diet phytate-P. In the large intestine net absorption of P (P < 0.05) occurred for all diets, while that of Ca (P < 0.05) only when pigs were fed the non-supplemented low-phytate diet.