Effect of varying dietary protein levels on growth and production of Chanos chanos (Forsskal) in inland saline groundwater: laboratory and field studies

Abstract

Two experiments were conducted to investigate the effects of varying dietary protein (35-45%) and energy levels (17.34-19.44 kJ g )1 ) on the growth performance of milkfish (Chanos chanos) maintained under laboratory (experiment 1) and field conditions (Experiment 2) in inland saline groundwater. The results of experiment 1 (initial weight of fish: 0.25 g) revealed that, irrespective of the protein source (fish meal or processed full fat soybean), fish fed a diet containing 40% protein showed significantly (p < 0.05) higher growth in terms of live weight gain and specific growth rate, low feed conversion ratio [1.71 (fish meal) and 1.58 (soybean)], high nutrient retention (gross protein retention: 28.59 and 31.05%; gross energy retention: 24.23 and 26.04%), apparent protein digestibility (81.74 and 85.91%) and digestive enzyme activity (specific protease and amylase). An observation on the postprandial excretion of metabolites (N-NH 4 and o-PO 4 ) indicated significantly (p < 0.05) low levels of these metabolites in aquaria where the fish were fed 40% dietary protein irrespective of the protein source. The results of experiment 2 also indicate (initial weight of fish: 4.43 g) a significantly (p < 0.05) higher growth performance (weight gain, biomass, specific growth rate, growth day )1 and fish production) in ponds where the fish were fed 40% dietary protein. Irrespective of the experimental conditions (laboratory/field), feeding the fish higher dietary protein levels (beyond 40%) not only repressed growth performance but also affected proximate composition by lowering protein accumulation and energy assimilation. An investigation on the effects of feeds on water quality parameters revealedthat values for total alkalinity, NH 4 -N, NO 3 -N, turbidity, total dissolved solids and parameters indicative of productivity (chlorophyll a, net primary productivity and plankton population) increased significantly (p < 0.05) from treatments 1-3 (35-40% protein) and declined thereafter, in treatment 4 (42% dietary protein), indicating that water quality characteristics correlated well with fish growth. The results suggest that in order to obtain a high-yield in milkfish culture system the fish should be fed supplementary diets containing appropriate (40%) protein levels, especially when the stocking rates are high.

Effect of Dietary Protein Level on Growth Performance and Blood Parameters of Marbled SpinefootSiganus rivulatus

“…However, increasing dietary protein level had no effect on fish body protein proportion. Similar findings were reported for various fish species, which also show no effect of dietary protein level on body protein levels (Jana et al 2006;Salhi et al 2004). Apparently, as long as the fish are getting enough energy for maintenance from nonprotein sources, and enough protein for production, their body protein content will not change.…”

The effect of protein levels on growth, postprandial excretion and tryptic activity of juvenile mulletMugil platanus(Günther)

“…Trypsin activity decreased with increasing dietary protein levels. A reduction in trypsin activity has also been shown for other species when fish are fed diets with protein content in excess of their requirement (Jana et al 2006; Mohanta et al 2008).…”

“…Thereafter a trend for growth depression as the protein content of the diet was increased was observed, especially at 500 g kg −1 CP. Studies with several teleosts have reported similar growth responses in fish, with manifestation of growth depression in response to excessive levels of dietary protein (Papaparaskeva‐Papoutsoglou & Alexis 1986; Horn, Mailhiot, Fris & McClanahan 1995; Elangovan & Shim 1997; Yang et al 2002; Jana, Garg, Barman, Arasu & Patra 2006; Martínez‐Palacios et al 2007).…”

Different Dietary Levels of Protein to Lipid Ratio Affected Digestive Efficiency, Skeletal Growth, and Muscle Protein in Rainbow Trout Families

“…The growth efficiency of several fish species has been studied through variation of dietary protein levels, and the results have shown not only the relationships between dietary protein concentration and physiological parameters of consumption, growth, and protein content in body or muscle, but also shown certain increased levels of dietary protein limited consumption and growth of the fish recently, that is, [1][2][3][4][5][6][7][8][9]. Increased growth is usually not associated with an increase in protein deposition rate, that is, [10][11][12], but rather an increase in lipid deposition rate, that is, [8,13].…”