Effects of microbial phytase supplementation of a barley-soybean meal diet on the performance and bone mineralization of growing-finishing pigs

Authors

• Eija Helander Department of Animal Science, P.O. Box 28, FIN-00014 University of Helsinki, Finland

DOI: https://doi.org/10.23986/afsci.72715

Abstract

The study evaluated the effect of a phytase supplement, produced by Aspergillus niger, on the performance of 72 growing-finishing pigs (28-101 kg). Chemical and physical parameters of the tibia and fibula bones were measured. The control diet (diet 1) was formulated to be adequate for pigs with respect to all nutrients, and diets 2 and 3 with respect to all other nutrients except total phosphorus (P). The P source of the control diet was dicalciumphosphate (dihydrate), while no inorganic P was added to diets 2 and 3. Diet 3 was supplemented with phytase, 720 U/kg feed. The average daily gain (ADG) and the feed conversion ratio (FCR) of the control pigs were significantly better than those of the groups without inorganic P. Phytase improved the ADG (p <0.01) and the FCR during the first 45 days (28- 60 kg). The pigs on diet 2 were able to grow as well as the other pigs when they became heavier (between 60-100 kg), so that at the end of the trial there was no significant difference between diets 2 and 3 for these parameters. No signs of leg weakness were observed in the growing pigs on any of the diets. The density (p < 0.01) and the breaking strength (p < 0.01) of the tibia bone were reduced (p < 0.01) on low-P diets compared to control diet. Phytase supplementation improved the density of the tibia bone (p < 0.001) compared to diet 2 and tended to improve the breaking strength, but the difference was not significant. No differences were found in the ash or P contents of the fibula bones. Phosphorus emissions were markedly reduced on diets 2 and 3. On the basis of the results it is not possible to recommend to replace inorganic P totally by phytase in growing-finishing pigs on barley-SBM diets.