Thirty crossbred sows (PIC-22) were used to investigate the effects of phytase on phosphorus utilization and the lactation performance of sows for two dietary inorganic phosphorus contents in maize-soya bean meal diets. The sows were allotted to treatments on day 100 of gestation. The treatment diet (Phytase) contained 5.4 g total phosphorus/kg with added phytase (Natuphos®) at 500 Phytase Units (PU)/kg diet and the control diet (Control) contained 7.4 g total phosphorus/kg without added phytase. Chromic oxide (2.5 g/kg) was added to the diets as a marker to determine apparent digestibility of feed composition. Blood samples were collected from the anterior vena cava at farrowing and at weaning to determine serum inorganic phosphorus and urea nitrogen. The coefficient of total tract apparent digestibility (CTTAD) of total phosphorus, organic phosphorus, crude protein and organic matter in the phytase diet was, respectively, 0.73, 0.61, 0.73 and 0.83, which was significantly higher (P < 0.01) than 0.59, 0.28, 0.62 and 0.77 in the control diet. Total phosphorus content in the faeces of sows fed the phytase diet decreased by 27.2% compared to the faeces of sows fed the control diet (P < 0.01). The serum inorganic phosphorus concentrations (107 and 103 mg/1 for control and phytase diets, respectively) at farrowing were higher (P < 0.01) than the serum inorganic phosphorus levels (90 and 91 mg/l for control and phytase diets) at weaning. The sow body weights and backfat changes, litter sizes, and litter weights at weaning were not influenced by a reduction in inorganic phosphorus and by a concomitant supplementation of phytase.
Bibliographical noteFunding Information:
The work reported here was conducted at the Southern Research & Outreach Center, University of Minnesota. The authors would like to thank Minnesota Department of Agriculture for funding the project, and to Dick Goetz, Gary Dobberstein and Scott Jones for assistance with animal care.