Dietary valine requirement of juvenile blunt snout bream (Megalobrama amblycephalaYih, 1955)

Abstract

Summary An 8‐week feeding trial was carried out to test the hypothesis that adequate dietary valine might improve growth, feed utilization and protein content in blunt snout bream, whereas a valine deficiency might have adverse effects on these parameters. Six isonitrogenous (34% crude protein) and isoenergetic (14.2 MJ kg−1 digestible energy) experimental diets were formulated to contain graded valine levels (0.66, 0.95, 1.26, 1.55, 1.87 and 2.16% of dry weight) at about 0.30% increments replaced by equal proportions of glycine. At the end of the experiment the survival rate was not significantly affected by the dietary valine level. Final weight, weight gain (WG), specific growth rate (SGR), feed efficiency ratio (FER) and protein efficiency ratio (PER) increased with an increasing dietary valine level up to the 1.26% diet, and thereafter remained relatively constant. Dietary valine levels significantly affected the viscerosomatic index, but not the hepatosomatic index or condition factor. The dietary valine levels significantly affected the protein contents of whole body and plasma. Dietary valine supplementation significantly increased the plasma valine concentration, but not the levels of other branched‐chain amino acids (isoleucine and leucine). Based on SGR and FER, the optimal dietary valine requirements of juvenile blunt snout bream were determined to be 1.32% of the diet (3.88% of dietary protein) and 1.26% of the diet (3.71% of dietary protein), respectively, using broken‐line regression analysis.

Dietary valine requirement of juvenile Nile tilapia,Oreochromis niloticus

“…Previous research has established the requirement of valine as an EAA needed for protein synthesis and growth stimulation in fish (NRC, ). In this study, data for Nile tilapia fed the formulation with the lowest level of valine showed significantly lower values for WG, SGR, PER and PRE, but a higher FCR, when compared with all other treatment groups; this result is consistent with previous reports of feeding trials with mrigal carp (Ahmed & Khan, ), red sea bream (Rahimnejad & Lee, ) and blunt snout bream (Ren et al., ). The results demonstrated that the growth performance and feed utilization efficiency of juvenile Nile tilapia were significantly improved by dietary valine supplementation, suggesting that valine is an EAA for Nile tilapia whereby the juveniles are able to assimilate the valine crystal for growth.…”

“…Also, the leucine and isoleucine contents of fish muscle were not affected by the varying the concentrations of dietary valine, similar to feeding trials with fingerling catla (Zehra & Khan, ), indicating the absence of antagonism among the branched‐chain amino acids in fish fed diets containing variable levels of valine. In addition, the moisture, lipid and ash contents of sampled juveniles showed no change in relation to dietary valine level, similar to the data reported for blunt snout bream (Ren et al., ). However, whole‐body lipid composition was observed to decrease with dietary valine supplementation in red sea bream (Rahimnejad & Lee, ) and Jian carp (Dong et al., ), whereas an increase in lipid content was recorded for mrigal carp (Abidi & Khan, ); the mechanisms of these differences need to be determined in further studies.…”

“…The broken‐line regression relationship between WG and dietary valine level indicated an optimum valine requirement for Nile tilapia juveniles at 11.5 g/kg of dry diet, equivalent to 41.1 g/kg of dietary protein, which is higher than the dietary valine values reported for blunt snout bream (38.8 g/kg of dietary protein; Ren et al., ), Catla catla (30.9 g/kg of dietary protein; Zehra & Khan, ), mrigal carp (38.0 g/kg of dietary protein; Ahmed & Khan, ), Indian major carp ( Labeo rohita , 37.5 g/kg of dietary protein; Abidi & Khan, ), Jian carp (40.0 g/kg of dietary protein; Dong et al., ), red sea bream (20.0 g/kg of dietary protein; Rahimnejad & Lee, ) and lake trout ( Ictalurus punctatus , 29.6 g/kg of dietary protein; Hughes, Rumsey, & Nesheim, ), but lower than the value reported for grass carp ( Ctenopharyngodon idella , 47.7 g/kg of dietary protein; Luo et al., ). Together, these data suggest substantial variation in the optimal valine requirement among different fish species.…”

“…The diets were made isonitrogenous (280 g/kg crude protein) and isoenergetic (16.06 MJ/kg gross energy) by adjusting the level of L‐glycine as described by Ren et al. (). All dry ingredients were thoroughly mixed in a Hobart‐type mixer after adding lipid and double‐distilled water.…”

“…Valine is an EAA for fish growth (Nose, ), as it is involved in many biological processes, such as protein synthesis, tissue repair and maintaining nitrogen balance (Brosnan & Brosnan, ). Previous studies on a variety of fish species, such as mrigal carp ( Cirrhinus mrigala ) (Ahmed & Khan, ), Catla catla (Ravi & Devaraj, ), red sea bream ( Pagrus major ) (Rahimnejad & Lee, ), blunt snout bream ( Megalobrama amblycephala ) (Ren et al., ) and Jian carp ( Cyprinus carpio var. Jian) (Dong et al., ), have suggested that valine deficiency will reduce growth and feed utilization.…”