Potassium diformate in shrimp

Pond production of intensively farmed white-leg shrimps, Litopenaeus vannamei (Boone, 1931), exceeded 2 million t in Central America and Southeast Asia in 2007, achieved through high-quality shrimp-feed supply in modern aquaculture. Despite progress in shrimp nutrition and new feed formulation strategies in recent years, disease outbreaks caused by pathogenic bacteria in shrimp ponds often result in significantly increased mortalities. Recent research in intensively managed fish production suggests that dietary organic acid salts, like potassium diformate, can overcome such problems. However, data on the effect on shrimp survival are still missing. A trial was therefore carried out to challenge juvenile white-leg shrimp with the bioluminescent bacteria V. harveyi (5 × 106 CFU/ml), which causes regularly increased mortalities in shrimp culture. The trial consisted of a negative control and two treatment groups (0.2% and 0.5% KDF) with 30 shrimp (mean body weight of 11.0±0.8g) in each group and was carried out in 150 litre fiberglass tanks filled with 70 litres, at a mean temperature of 27°C and a salinity of 20 ppt. Shrimp were fed three times a day, with a commercial diet containing 32% crude protein. After 10 days, mortality in the non-treated shrimp was significantly higher (P<0.01; 76.6±5.8%) compared to shrimp which had been fed with KDF at both inclusion levels (50.0±10.0% for both 0.2% and 0.5% KDF-dosage). It can be therefore concluded that dietary potassium diformate is able to reduce mortality in white-leg shrimp caused by the gram-negative pathogenic bacteria V. harveyi.