Nutritional challenges in white sturgeon aquaculture, particularly during the grow-out phase, have been linked to suboptimal commercial diets, often resulting in excessive visceral fat deposition and fatty ovaries. These issues suggest inefficiencies in nutrient partitioning, prompting the need for diet optimization. A 2×3 factorial experiment was conducted to evaluate the effects of varying dietary protein and lipid levels on growth performance, nutrient utilization, and mesenteric fat deposition in white sturgeon. Six experimental diets were formulated with two levels of dietary protein (40% and 45%) and three levels of dietary lipid (15%, 20%, and 25%).
A total of 264 one-year-old white sturgeon, with an average initial weight of 930.29 g ± 25.58 g, were randomly allocated to 12 tanks (1500L), with two replicates per diet (n=22 fish per tank) for 20 weeks. The fish were fed a 6mm pellet diet at 2% body weight per day, using a combination of hand feeding and automatic feeders, and growth was monitored every four weeks. Growth trends were analyzed using simple linear regression, with weight gain modeled as a function of time and dietary treatment.
In the 45% protein diet, fish fed the 25% lipid diet showed the highest growth rate (83.12 g/week) and the lowest feed conversion ratio but had higher liver fat accumulation (HSI = 2.01). Fish fed the 20% lipid diets showed moderate growth while minimizing liver and visceral fat accumulation (HSI = 1.55, VSI = 6.67). In the 40% protein diet, fish fed the 15% lipid had the slowest growth rate (65.28 g/week) and the highest visceral fat accumulation (VSI = 8.15). These findings suggest that a 45% protein and 20% lipid diet provides the best balance between growth and reduced fat accumulation in on-growing white sturgeon and that higher lipid levels may contribute to excess fat deposition. This study is funded by the USDA Western Regional Aquaculture Center.