Effect of Dietary Vitamin C Concentration on Growth and Health of Largemouth Bass Micropterus salmoides.
Daryl Weldon, Ruguang Chen, and Rebecca Lochmann

The objective was to determine a minimum dietary requirement of vitamin C for growth and prevention of deficiency signs in juvenile largemouth bass in a feeding trial. Diets contained 0, 25, 50, 100, 250, or 500 mg of ascorbic acid (AA) per kg of diet. Feed intake and growth were highest in fish fed diets with 50, 250, or 500 mg AA/kg for 14 wks. Fish fed diets with 0 or 25 mg AA/kg had lower survival than fish fed other diets. Deficiency signs in fish fed diets with 0 or 25 mg AA/kg included anorexia, fin erosion, hemorrhaging, and alterations in tissue around the eyes. Fifty mg AA/kg diet was sufficient for good growth and survival, but more vitamin C was needed for complete prevention of deficiency signs, and to maximize some immune functions and survival of heat stress. 

An Enzyme-linked Immunosorbent Assay is not Effective for Sampling Insulin Response to Carbohydrates in Red Pacu, Piaractus brachypomus, and Black Pacu, Colossoma macropomum.
Todd Sink and Rebecca Lochmann

The objective was to evaluate the potential of an insulin assay as tool in assessing carbohydrate utilization in pacu for diet development. We conducted procedures to validate an enzyme-linked immunosorbent assay (ELISA) for detection of plasma insulin concentrations in red and black pacu. Pacu were fed a commercial catfish diet containing approximately 40% soluble carbohydrates (32% protein, 6% fat). Both species were then bled and plasma was used for validation of the assay. An ELISA was conducted using the Food and Drug Administration’s Center for Veterinary Medicine validation of analytical procedures methodology. The results from this assay validation study indicate that an ELISA insulin kit was not suitable for experimental detection of blood plasma insulin concentrations in RP and BP.