Abstract:
A 60-day experiment was designed to assess the effect of different ratios of fish meal
(FM): camelina meal plant protein (CM) on growth response and relative gene expression of growth promoting factors, feed utilization potency, digestive enzymes activities, apparent digestibility (ADC),
stress response, non-specific immunity of Pagrus major. Four isonitrogenous (490.7 g/kg of crude
protein) and isolipidic (91.5 g/kg total lipid) experimental diets were formulated and designated as
camelina meal (CM0), soyabean meal (SBM20.5), CM20.5, and CM33 based on protein contents. At
the end of the feed trial, significantly higher (p < 0.05) weight gain, specific growth rate, and feed
intake but lower feed conversion ratio were recorded in fish fed CM0, SBM20.5, and CM20.5 than
fish fed CM33. The lowest growth, feed utilization, enzyme activity, and digestibility were recorded
in fish fed CM33. Significantly higher pepsin, amylase, and protease activities were observed in
fish fed CM0, SBM20.5, and CM20.5 diets than fish fed CM33. The highest ADC of protein was
recorded in fish fed CM0, SBM20.5, and CM20.5 diets. Hematocrit levels were depressed CM33 while total serum protein, total cholesterol, triglyceride, blood urea nitrogen, total bilirubin, aspartate
aminotransferase, and alanine aminotransferase were not significantly changed by the inclusion
of CM. Non-specific immune variables (lysozyme activity, peroxidase activity in serum and nitro
blue tetrazolium) in fish fed CM0, SBM20.5, and CM20.5 were significantly higher than in fish fed
CM33 diet. The superoxide dismutase of fish fed CM20.5 was not significantly different from CM0
and SBM20.5 (p > 0.05). Catalase and low salinity stress test show that CM0, SBM20.5, and CM20.5
were not significantly (p > 0.05) different, while CM33 was significantly lower than the rest of the
diets. TBARs show that CM20.5 and CM33 diets were significantly different (p < 0.05), but CM20.5
was not significantly different from SBM20.5. Significantly higher hepatic IGF-1 and IGF-2 mRNA
expression was found in fish-fed diet groups CM0, SBM20.5, and CM20.5 than fish fed CM33. The
present study indicated that the addition of CM up 205 kg/kg to diet maintains growth, digestive
enzymes, nutrient digestibility, immunity, stress resistance, and feed utilization efficiency of red
sea bream.
