Novel Protein Ingredients Alter Feed Intake, Digestibility and Faecal Stability in Atlantic Salmon ( Salmo salar )
Year: 2026
Type: article
Abstract: Aquafeeds can be formulated to improve feed utilisation and faecal stability through the careful selection and combination of ingredients. Increasing ingredient demand in the aquaculture industry has expanded the diversity of raw materials used in modern feeds. In the present study, novel feed ingredients currently used at low levels in salmon feeds were evaluated in experimental diets containing 15% guar protein, insect meal, bacterial meal or algal meal, while distiller-dried grain with solubles (DDGS) was included at 8% to maintain comparable dietary protein levels. The effect of these ingredients on faecal properties was assessed using a combination of gastrointestinal (GI) and faecal analyses after 4-week feedings. Feed and faeces were continuously collected at tank outlets throughout the trial. Compared with stripped and dissected distal-gut samples, outlet-collected faeces yielded consistently higher apparent digestibility (AD) estimates, most likely due to the loss of water-soluble dry matter during transport in water. Faecal collection efficiency ranked as follows: guar protein > bacterial meal > insect meal > DDGS > control > algal meal. Using guar protein as a substitute for guar gum in recirculating aquaculture systems (RAS) feed appears to be a promising strategy for improving faecal collection in high-energy salmon feeds. Bacterial and insect meals in feeds also improved faecal collection. However, the reduced palatability of bacterial meal and lower digestibility of insect meal led to a reduced growth performance. Although modifying the formulation may improve the performance of these ingredients, the precise inclusion levels have not been established, and the effects of reduced inclusion rates or supplementation of feed attractants on faecal properties are still unknown. Our results indicate that ingredient composition can modulate faecal properties through different mechanisms, including altered mucus production, digesta viscosity and water reabsorption. Whereas guar led to faecal pellets with lower dry matter and higher mucus content, increased water reabsorption produced drier faecal pellets in salmon fed feeds high in fish meal, bacterial meal and insect meal.
Source: Aquaculture Nutrition
DOI: 10.1155/anu/1009249
Institution: Nofima
Language: English
Subfield: Aquatic Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $2,350
Funder: Norges Forskningsråd
OpenAlex ID: W7225390682