Cholesterol and short-chain fatty acids in diets for Atlantic salmonSalmo salar(L.): effects on growth, organ indices, macronutrient digestibility, and fatty acid composition

Abstract

The influence of dietary cholesterol (CHOL) and short‐chain fatty acids (SCFA; sodium salts of acetic, propionic and butyric acid, 5:5:2 w/w/w) on growth, organ indices, macronutrient digestibility, and fatty acid composition of Atlantic salmon Salmo salar was investigated. Salmon (initial average weight 0.7 kg) held in seawater (7°C) for 175 days were fed one of six diets: 1, without CHOL/SCFA supplement; 2, with 0.5% SCFA; 3, with 2.0% SCFA; 4, with 1.0% CHOL; 5, with 1.0% CHOL and 0.5% SCFA; 6, with 1.0% CHOL and 2.0% SCFA. Neither SCFA nor CHOL supplements had any significant effects on specific growth rate (SGR), mortality, apparent digestibility coefficients (ADC) of macronutrients, total lipid content. Hepatosomatic index (HSI) was slightly increased in salmon fed the CHOL supplement (P < 0.05). Hepatic CHOL concentration, but not the hepatic CHOL pool, was significantly increased (P < 0.001) by dietary CHOL supplementation. The fatty acid compositions of fillet and gut tissues were not influenced by dietary treatment, while significant effects of CHOL supplements were observed in faeces and liver. Less saturated fatty acids and more mono‐ and poly‐unsaturated fatty acids were excreted with faeces in salmon fed CHOL supplements. Salmon fed CHOL supplements significantly reduced the relative concentration of hepatic palmitic acid (C16 : 0), arachidonic acid (C20 : 4 n‐6) and docosahexaenoic acid (C22 : 6 n‐3), while the contents of oleic acid (C18 : 1 n‐9) and eicosenoic acid (C20 : 1 n‐9) were significantly increased. SCFA did not influence the observed effects of dietary CHOL. The present study shows that dietary CHOL supplements profoundly altered excretion and liver metabolism of individual fatty acids in salmon. The impact of this alteration on physiological performance has not been elucidated.

Dietary microencapsulated organic acids blend enhances growth, phosphorus utilization, immune response, hepatopancreatic integrity and resistance against Vibrio harveyi in white shrimp, Litopenaeus vannamei

“…Interestingly, despite organic acids blend potentially having synergistic activities (Thompson and Hinton, 1997;Chaveerach et al, 2002), the utilization of different OAB has been met with varied results showing a slight, but not significant, improvement to growth of tilapia (Petkam et al, 2008;Ng et al, 2009), no improvement to Atlantic salmon (Bjerkeng and Storebakken, 1999) It is believed that coating or encapsulating the organic acids may reduce leaching as well as to allow the organic acids to more easily reach the hepatopancreas and gut intact without dissociating. This is especially important for shrimp due to their slow feeding and feed pellet pinching feeding behavior.…”

Metabolism and Functions of Lipids and Fatty Acids in Teleost Fish

“…However, SCFA have had little positive effect since inclusion of SCFA up to 2% of total diet dry weight in Atlantic salmon diets had no effect on growth, mortality, lipid levels or fatty acid composition (Bjerkeng et al, 1999).…”

Additives in aquafeed

“…Another study found that the growth rates of intensively cultured South African abalone, Haliotis midae, can be significantly enhanced under favorable growth conditions through the addition of certain organic acids (1% acetic acid þ 1% formic acid, and 1% benzoic acid þ 1% sorbic acid) and organic acid salts (1% sodium benzoate þ 1% potassium sorbate) (Goosen et al, 2011). In other species, neither hybrid tilapia (Zhou et al, 2009) or Atlantic salmon Salmo salar showed any growth enhancement related to the inclusion of organic acids in the diet (Bjerkeng et al, 1999;Gislason et al, 1994). On the other hand, Anuta et al (2011) found that the addition of 0.4e2% commercial acid, based on calcium sulfate, did not change the performance parameters of Litopenaeus vannamei; however, they recorded an increase in the immune response and a change in the intestinal microbiota.…”