Effect of Feed Supplementation with Tripotassium Citrate or Sodium Chloride on the Development of Urinary Calcium Oxalate Crystals in Fattening Pigs.

The present study investigated whether dietary supplementation of tripotassium citrate or NaCl reduced the prevalence of calcium oxalate dihydrate (COD) uroliths in fattening pigs on a farm with a high prevalence of COD uroliths. Each group (control, TPC, NaCl) consisted of three batches of approximately 260 fattening pigs each. Performance, water intake, markers for bone resorption (CTX) and bone formation (osteocalcin) and urinalysis from samples taken at the farm and in the slaughterhouse were investigated. Performance parameters, feed and water intake, CTX and osteocalcin were not significantly different between the groups (p > 0.05). The main crystals found were struvite, COD, calcite and amorphous crystals. The prevalence of COD crystals was lower in samples from the slaughterhouse in each group. Microscopic and biochemical examination of urine showed large differences between samples from the farm and the slaughterhouse. In conclusion, there were no beneficial effects of feed supplementation with TPC or NaCl on the prevalence of COD crystals but TPC has a clear promoting influence on the development of alkaline calcite crystals. Urinalysis from samples taken at the slaughterhouse does not fully reflect the situation on the farm.