The effects of dietary protein levels with amino acid supplementation on the growth performance, haematological profile and histology of meagre (Argyrosomus regius) in two different size classes

Abstract

A 12‐week feeding trial was conducted to estimate the effects of supplemented amino acids (lysine and methionine) with different dietary protein levels on growth, haematology and liver histology in meagre (Argyrosomus regius) at two different sizes: fingerling (15.2 g) and juvenile (44.4 g). Six practical diets were prepared, and three of these practical diets were formulated with 40 (P40), 44 (P44) and 48% (P48) crude protein without supplementation of amino acids. Other three diets having same protein levels were supplemented with lysine and methionine (P40AA, P44AA and P48AA) to bring these amino acids level up to that estimated to be at the least in the 48% protein diet. Final mean weight (FMW) and specific growth rate (SGR) of P48AA in fingerlings were higher than that of 40AA. According to FMW and SGR of juveniles, there was interaction found between dietary protein levels and the supplementation of amino acids. The FMW and SGR of meagre fed P44AA were higher than that of fish fed the other diets, except fish fed the P48. Economic profit index, packed cell volume and haemoglobin for juvenile meagre were significantly improved with the dietary protein level and amino acid supplementation. The liver tissues of the P48 group in both sizes displayed better structure compared with the other groups. In conclusion, dietary crude protein content of practical diets for juvenile meagre could be reduced from 48% to 44% by adding essential amino acids with an enhancement in growth, health and economic profit.

Effects of reduced protein level and dietary amino acid supplementation on growth, body composition and intestinal morphometry of silver catfish ( Rhamdia quelen )

“…Quantitative AA requirements for fish can vary between feed composition, animal age, experimental conditions and species (Ahmed et al., 2018; Güroy et al., 2017; Michelato et al., 2016). Lys is the first limiting AA in the fish diet (NRC, 2011).…”

“…On the other hand, Lys supplementation above the required value has demonstrated positive effects on the growth and use of nutrients (Li, Zhou, Mo, Pan, & Gan, 2017; Prabu, Felix, Uma, & Praveenraj, 2019), fillet yield (Michelato et al., 2016), mobilization of body fat (Cheng, Hardy, & Usry, 2003; Li et al., 2017), muscle carnitine content (Li et al., 2017), liver function and haematological and biochemical status of fish (Prabu et al., 2019; Li et al., 2017). In addition, AA supplementation allows for a reduction in the amount of protein (Rawles, Green, McEntire, Gaylord, & Barrows, 2018) and the cost of diets (Güroy et al., 2017).…”

“…In the present study, the cost of food was lower in the diet supplemented with Lys only. Although supplementation with synthetic AA increases the cost of the diet, the increase in RWG and the reduction in the excretion of nitrogen compounds justify its use (Abimorad et al., 2009; Güroy et al., 2017). On the other hand, the greater RWG in the short term reduces the slaughter time and can guarantee greater benefit to the producer (Botaro et al., 2007).…”

“…Protein is one of the most expensive nutrients in the formulation of diets. The use of vegetable by‐products and proteins to replace fishmeal allows for a reduction in food costs (Güroy et al., 2017; Lazzari et al., 2008; Santos & Meurer, 2018). However, plant sources have antinutritional factors, deficiency of essential amino acids (AA) and lower digestibility and palatability of nutrients.…”

“…By increasing the level of Lys and Met, the supplemented diet can improve the use of other excess AA, optimize anabolism and maximize the use of proteins in the diet (Jiang et al., 2018). Recent studies show that dietary supplementation of Lys and Met in diet improves growth, feed intake, nutrient deposition, digestive enzyme activity, antioxidant capacity and ammonia excretion in fish (Gan et al., 2012; Güroy et al., 2017; Jiang et al., 2016, 2018; Yang, Liu, Tian, Liang, & Lin, 2010).…”