Optimization of the Balance between Protein, Lipid and Carbohydrate in Diets for Lumpfish (Cyclopterus lumpus)

Abstract

The aim of this study was to investigate how the dietary balance between protein, lipid, and carbohydrate affects growth, welfare, and health with focus on immune responses, in lumpfish of body weight ranges 1.7-10 g and 15-50 g. A three-component mixture design, with simultaneous variation of the three macronutrients was applied. Growth, tissue and plasma nutrient composition, welfare, cataract frequency, and immune responses in leukocytes isolated from the fish head kidney were studied. Most responses were linear and driven by dietary lipid level, with minor effects of carbohydrate and protein. The growth in 1.7-10 g fish followed a special cubic model with no clear optimum. The fastest growth in the 15-50 g fish was obtained with the diet containing 55% protein, 17% fat, and 6% carbohydrate. The high dietary levels of lipid also gave high lipid levels in the tissues and a trend of improved welfare score, but there were no effects on cataract. The diets with minimum and maximum protein gave suboptimal immune responses in isolated head kidney cells of the 15-50 g fish, while the fastest growing fish showed normal immune responses. We propose that diets for lumpfish from 10-50 g body weight should contain approximately 55% protein, minimum 10% lipid, and maximum 10% carbohydrate. These diets will also be suitable for lumpfish of 1.7-10 g.

A Screening Study on Effects Varying Dietary Macronutrient Composition on Gut Functions in Lumpfish (Cyclopterus lumpus)

“…As mentioned in the introduction, our previously published results from E1, indicated that peak performance of lumpfish weighing between 15 and 50g, based on growth, body composition, welfare score and immune responses in isolated head kidney cells, would be obtained with a diet containing 55% protein, minimum 17% lipid and maximum 6% carbohydrate (Hamre et al, 2022). The present results, showing very low starch digestibility, suggest that dietary starch level should be limited to about 6%.…”

“…Details of the experimental conditions are published in (Hamre et al, 2022). In brief, the fish were produced by a commercial hatchery and transported to Nofima's research facility at Sunndalsøra, Norway.…”

“…Since it is not certain if strong immune responses in unchallenged tissues is positive or negative for the fish, a recommendation on the optimal macronutrient composition cannot be given based on the present results regarding immune function. However, according to Hamre et al (2022), head kidney cells from fish fed the diet with the maximum level of protein, showed a suboptimal immune response when challenged with lipopolysaccharide (LPS). Fish fed the diet with the highest growth (55, 17, 6) had a normal immune response.…”

“…The main part of the results stems from a feeding experiment (E1) conducted to estimate optimal balance between protein, lipid, and carbohydrates in diets for lumpfish of 15-50 g, based on observations of growth and feed conversion ratio, physiological characteristics of the intestine, mucosal and systemic immune responses. Results regarding growth performance, with more than three times increase in weight, body composition, welfare scores, and systemic immune responses are published in the paper of Hamre et al (Hamre et al, 2022) with the following conclusion: The best growth and welfare were obtained in fish fed a diet with 55% protein, 17% lipid and 6% carbohydrates. However, to meet the wish from farmers of reducing growth, diets for lumpfish weighing from 10-50 g body weight should contain approximately 55% protein, minimum 10% lipid and maximum 10% carbohydrate.…”

Effects of Dietary Protein and Lipid Levels in Practical Formulation on Growth, Feed Utilization, Body Composition, and Serum Biochemical Parameters of Growing Rockfish Sebastes schlegeli

“…This is defined as protein-sparing effect of lipid, which is beneficial to reduce feed cost and nitrogenous waste output in fish farming [4]. In recent years, some research findings have evidenced that diets with appropriate protein and lipid levels are performing well in terms of fish growth and feed utilization, while a sparing effect on protein by increased dietary lipid has also been found in several fish [5][6][7]. However, most commercial feeds containing relatively high level of protein and lipid are applied in offshore cage farming, resulting in feed waste, and potential environmental pollution.…”