Effects of dietary onion (Allium cepa) powder on growth performance, hemolymph indices and fillet organoleptic properties of juvenile narrow-clawed crayfish,Astacus leptodactylus leptodactylusEschscholtz, 1823

Abstract

A 18-week feeding trial was carried out under controlled conditions to compare the effects of onion powder (OP) at six levels (5, 10, 20, 30, 40 and 50 g/kg) on the growth performance, nutritional efficiency indices, hemolymph indices and fillet organoleptic properties of juvenile (5.62 ± 0.39 g) crayfish. The significantly (p < .05) highest values of final weight (71.30 g) and SGR (2.02% per day) and the lowest FCR (1.03) were observed in the juvenile crayfish fed the diet containing 40 g OP/kg. The juvenile crayfish fed the diet containing 40 g OP/kg had the significantly (p < .05) highest THC (105.27 × 10 5 cell/ml), HC (98.33 × 10 5 cell/ml), SGC (38.54 × 10 5 cell/ml) and LGC (49.51 × 10 5 cell/ml). The crayfish fed the levels of dietary OP higher than 30 g/kg showed the significantly (p < .05) higher values of SOD (4.07-4.30 U/min) and LYZ (6.73-7.20 U/min) compared with those fed 5, 10, 20 and 30 g of dietary OP/kg and control. Polynomial regression of SGR, FCR, PPV and PER suggested that the optimum dietary OP level could be higher than 30 and <50 mg/kg in crayfish reared in culture conditions. K E Y W O R D S additive, crayfish, growth, immunity, onion powder, quercetin

Effect of dietary encapsulated organic salts (Na‐acetate, Na‐butyrate, Na‐lactate and Na‐propionate) on growth performance, haemolymph, antioxidant and digestive enzyme activities and gut microbiota of juvenile narrow clawed crayfish, Astacus leptodactylus leptodactylus Eschscholtz, 1823

“…Feeding crayfish with different synbiotics (galactooligosaccharide + Enterococcus faecalis and galactooligosaccharide + Pediococcus acidilactici ) improved immune responses and stress resistance compared with those fed the diets containing only probiotics or prebiotics (Safari & Paolucci, 2017a; Safari & Paolucci, 2017b; Safari & Paolucci, 2017c; Safari et al., 2017). The positive effects of synbiotics can be related to the increase in the dose content and/ or produce a mixture of SCFAs and, mainly, butyrate in the digestive tract.…”

“…At the beginning of the feeding trial, total aerobic bacteria (TAB), lactic acid bacteria (LAB), Escherichia coli and fungi (yeast and mould) counts of the hepatopancreas were determined by random sampling 15 crayfish from the stock. As described previously (Safari & Paolucci, 2017a; Safari & Paolucci, 2017b; Safari & Paolucci, 2017c; Safari et al., 2014), at the end of the experiment, crayfish (15 individuals per a treatment) were transported alive to the laboratory, anaesthetized with ice, rinsed with benzalkonium chloride (0.1% for 60 min) and dissected with a scalpel. Then, the hepatopancreas was removed and homogenized with sodium chloride (0.9 w/v) using a homogenizer (DI 18 Disperser).…”

“…The homogenate was centrifuged at 5,000 g , 4°C, 5 min, and the sample (100 µl) was put onto plate count agar (PCA; Merck Co.), de Man, Rogosa and Sharpe media (MRS; Merck Co.), MacConkey agar (Merck Co.) and potato dextrose agar (PDA; Merck Co.) at triplicates in order to determine TAB, LAB, E. coli and fungi counts, respectively. Colony‐forming units (CFU)/g were calculated from plates containing 30–300 colonies (Safari & Paolucci, 2017a; Safari & Paolucci, 2017b; Safari & Paolucci, 2017c; Safari et al., 2014).…”

“…Optimal diet formulations are promising strategies to improve the production efficiency and the health condition of the farmed species, while limiting the use of antibiotics and chemicals, widely used to control mortality and infections (Glencross et al., 2007; Safari et al., 2014a). Using feed additives including prebiotics (Safari et al., 2014b), probiotics (Valipour et al., 2019), synbiotics (Safari & Paolucci, 2017a; Safari et al., 2017), nucleotides (Safari et al., 2015), L‐carnitine (Safari et al., 2015) and phytogenics, plant‐derived materials (Parrillo et al., 2017; Safari & Paolucci, 2017b) as generally recognized as safe (GRAS) materials have shown positive effects on the growth performance, immunity and the stress resistance of crayfish. In this regard, organic acids (OAs), well known as acidifiers (ACIs) and short‐chain fatty acids (SCFAs), were defined as by‐products of substrate fermentation with gastrointestinal microbiome (Ng & Koh, 2017).…”

Lactobacillus acidophilus and L. plantarum improve health status, modulate gut microbiota and innate immune response of marron (Cherax cainii)

“…Dietary supplementation of feed additives have significant impacts on growth, immunity and disease resistance of crustaceans 3,7,9,29,[37][38][39][40] . Probiotic in aqua diets, has positive influence on the growth and immune performance of commercially farmed shrimp and crayfish species.…”