Effect of increased dietary protein level in meagre (Argyrosomus regius) juvenile growth and muscle cellularity

Abstract

In this study, two different dietary protein levels were tested (500 and 600 g/kg) in meagre juveniles of approximately 2 g, to determine whether a higher body protein diet would favour muscle growth. Results showed that meagre survival and growth were not affected by different levels of dietary protein. However, a higher content of protein was observed in the body composition of meagre fed the P60 diet (656 g/kg versus 624 g/kg). When fish were 82 days after hatched (DAH), protein retention efficiency was significantly higher in fish that were fed the P50 diet (37.1% versus 32.5%). Muscle cellularity changed considerably from the beginning to the end of the trial. The contribution of fibre hyperplasia to muscle growth was reduced although still accounted for 30% in 96 DAH meagre. Several differences were found in the frequency of fibres with areas between 1,000 μm 2 and 2,200 μm 2 between younger and older meagre, but no effect was found associated with dietary protein. This study suggests that neither growth nor muscle cellularity of fast-growing juvenile meagre is positively affected by an increased dietary protein levels. K E Y W O R D Sgrowth, meagre, muscle cellularity, protein retention

Plant‐based diets fed to juvenile meagre Argyrosomus regius with low methionine and taurine supplementation led to an overall reduction in fish performance and to an increase in muscle fibre recruitment

“…On the contrary, D2 and D3 showed higher PER levels which led to a higher fish growth. The values obtained for PER were within the same range as the ones reported for meagre of approximately the same age (Chatzifotis et al ., 2012; Ribeiro et al ., 2015; Saavedra et al ., 2018b). PER results were consistent with the results obtained for protein retention where, again, the D1 diet showed lower values suggesting that protein is less retained or that protein synthesis might be limited due to methionine deficiency.…”

“…Fish growth is the result of two dynamic processes: muscle fibre enlargement (muscle fibre hypertrophy) and muscle fibre recruitment (muscle fibre hyperplasia). Only recently these processes have started to be looked at more carefully, but they are important tools to understand muscle growth by analysing the area and density of muscle fibres (Saavedra et al, 2018a(Saavedra et al, , 2018b. There are few studies focusing on the effect of dietary AA supplementation on muscle cellularity (Saavedra et al, 2019).…”

“…Meagre has acquired an important role in aquaculture diversification in the Mediterranean region. Most of its rearing is still based on seabream diets, and commercial diets are not available for larval and juvenile stages although the requirements on crude protein and lipids are already established (Saavedra et al, 2018a(Saavedra et al, , 2018b. Formulating suitable diets for meagre and correcting the AA imbalances caused by plant-protein diets is crucial to maximize growth, decrease nitrogen losses and improve overall meagre performance (Saavedra et al, 2009(Saavedra et al, , 2018a.…”

Untitled

“…These results are in accordance with other studies on juvenile stages (Alami-Durante et al, 1997;Silva et al, 2009), which further demonstrate that muscle growth is mainly due to fiber hypertrophy. Hyperplasia occurs via a stratified mechanism (within proliferation areas) or by a mosaic mechanism (in zones where larger fibers occur) in seabass Dicentrarchus labrax and meagre Argyrosomus regius (Alami-Durante, Olive, & Rouel, 2007;Saavedra et al, 2018). Mosaic hyperplasia is the main muscle growth process in juvenile and adult stages (Johnston et al, 2006).…”

“…Digestive enzymes found in the fish alimentary system directly affect digestion and absorption of nutrients, animal growth, and adaptability to the environment (Xia et al, 2017). The growth and digestibility responses to different dietary protein levels have been reported for several species, such as redclaw crayfish Cherax quadricarinatus (Figueiredo, Kricker, & Anderson, 2001), sea cucumber Apostichopus japonicus (Xia et al, 2017;Bai, et al, 2016), meagre Argyrosomus regius (Saavedra, et al, 2018), and pacific white shrimp Penaeus vannamei (Huang, Wang, & Lu, 2003). Although Kim et al (2016) evaluated the individual and combined effects of oxygen concentration and diet composition on growth and nutrient utilization of O. niloticus (Ling, Hashim, Kolkovski, Chong, & Chien, 2006), the effects of dietary protein levels on muscle quality and digestive enzyme activities of GIFT-O.…”