Chelated Potassium and Arginine Supplementation in Diets of Pacific White Shrimp Reared in Low‐Salinity Waters of West Alabama

Abstract

AbstractDietary supplements have been proposed as a potential remediation strategy to counteract mineral deficiencies in low‐salinity well waters (LSWW) used for shrimp culture in Alabama. Existing strategies (i.e., application of fertilizers such as K‐mag and muriate of potash) are costly to farmers attempting to raise levels of potassium (K+) in their ponds. Previous laboratory studies using dietary supplements of chelated K+ increased growth but not survival of Pacific white shrimp Litopenaeus vannamei reared in low‐salinity water. To determine whether this approach is applicable in the field, two growth trials were conducted in flow‐through outdoor tanks that used water from farm ponds. The first trial (6 weeks) was conducted simultaneously at two separate low‐salinity farms in west Alabama and evaluated two practical diets, one with a chelated K+ supplement and one without. One of these farms supplements K+ to its water and is considered a low‐stress environment (LSE), while the other farm does not supplement its water and is considered a high‐stress environment (HSE). Results indicated that dietary supplementation of K+ (1.0%) in the absence of an appropriate ionic profile (i.e., the HSE) failed to enhance growth or survival of Pacific white shrimp. Another 9‐week growth trial was conducted at the LSE farm. Shrimp were offered either a practical basal diet or the basal diet supplemented with 0.5% chelated K+, 1.0% chelated K+, or 0.4% arginine. Although no statistically significant effects of chelated K+ supplementation were observed, results of this experiment and two other experiments showed an increase in growth associated with chelated K+ supplementation, indicating a marginal benefit. Present results do not justify K+ supplementation of diets for Pacific white shrimp reared in inland LSWW. Better shrimp survival and growth are observed when K+ is added to culture waters to mitigate imbalances in Na:K and Cl:K ratios.