Dietary zinc requirement of fingerling Indian major carp, Labeo rohita (Hamilton)

Influence of dietary zinc on growth, zinc bioaccumulation and expression of genes involved in antioxidant and innate immune in juvenile mud crabs (Scylla paramamosain)

“…For instance, in the Zn requirement study in Chinese mitten crab, the initial weight of the crab was only 7•16 (SE 0•48) mg (24) , while the initial weight of mud crab in the present study was 14•96 (SE 1•11) g. Zn concentration in different tissues could reflect Zn utilisation (29) . In the present study, Zn concentrations in tissues increased with increased dietary Zn level, in agreement with previous studies in Chinese mitten crab (23) , grass shrimp (29) , grouper (Epinephelus malabaricus) (39) , hybrid tilapia (Oreochromis niloticus × Oreochromis aureus) (40) , Indian major carp (Labeo rohita) and yellow catfish (Pelteobagrus fulvidraco) (20) . Furthermore, the main tissue of Zn deposition was hepatopancreas, followed by muscle, and then carapace, which was similar to Chinese mitten crab where Zn concentration in hepatopancreas of crabs fed 85 mg/kg Zn was almost 4-fold higher compared with crab fed 5 mg/kg Zn (23) .…”

“…In the present study, the lowest MDA concentrations in haemolymph and hepatopancreas were observed in crabs fed the diets containing 68•5 and 97•3 mg/kg Zn, which indicated that appropriate levels of dietary Zn contribute to the reduction of peroxidation products largely due to the actions of the antioxidant enzymes (46) . Similar results were obtained in grass carp (Ctenopharyngodon idella) (26) , Indian major carp (20) , Nile tilapia (O. niloticus) (48) , Jian carp (Cyprinus carpio) (46) and yellow catfish (25) .…”

“…In the present study, lowest total SOD, Cu/Zn-SOD and CAT activities, and total antioxidation capacity and GSH levels were observed in crabs fed the diets containing 44•5 and 56•9 mg/kg Zn compared with those fed the diets containing 68•5 and 97•3 mg/kg Zn. Deficiency or excessive dietary Zn, decreasing biological efficiency of antioxidation enzymes and antioxidants, has been reported previously in other aquatic animals (15,20,25,26,46,48) . Production of MDA results from the peroxidation of PUFA, influencing cell membrane fluidity as well as the integrity of biomolecules, and is an important indicator of peroxidation (49) reflecting the antioxidant status of aquatic animals (27) .…”

“…Specifically, it is an essential cofactor for numerous enzymes and proteins involved in many physiological processes including nucleic acid, protein, fatty acid, phospholipid and carbohydrate metabolism that are critical to growth, reproduction and development of aquatic animals (15)(16)(17) . In addition, Zn has key roles in antioxidant defence and immune response partly as an integral constituent of Zn-dependent metalloenzymes such as Cu/Zn superoxide dismutase (Cu/Zn SOD) and alkaline phosphatase (AKP) (18,19) and so inhibits free-radicalinduced oxidative damage to cells and tissues and supports immune functions by interacting with minerals such as Se, Cu and Mg and several other metalloenzymes (20) . Therefore, there is an urgent need to understand the nutrition and metabolism of Zn in mud crab.…”

“…Although the mechanisms of dietary Zn functions in fish and shrimp have been studied (21,22) , little information is available on the nutritional role of Zn in crabs and, so far, only Zn requirement of Chinese mitten crab (Eriocheir sinensis) has been determined (23,24) . Deficiency of dietary Zn in fish results in decreased growth performance and survival rate, eye cataracts, skin lesions, bone malformations and short body dwarfism (12,20) , while excessive dietary Zn is toxic to fish and reduces antioxidant ability and sperm motility (25)(26)(27)(28) . In crustaceans, previous studies demonstrated that dietary Zn deficiency reduced the growth of Chinese mitten crab (23) , freshwater prawn (Macrobrachium rosenbergii) (15) , grass shrimp (Penaeus monodon) (29) and Pacific white shrimp (Litopenaeus vannamei) (30,31) , while excessive dietary Zn decreased digestive enzyme activities in freshwater prawn (15) .…”