A thesis submitted in partial fulfillment requirements for the degree of Master of Science, School of Environment, Resources and Development

Thesis (M.Sc.) - Asian Institute of Technology, 1990

The protein and energy requirements of two size groups of ma le red ti lap ia ( Ol'"l.!'.{u2022}oc:hl'"<:)m.:i..1r.: n.i. 1 c~t icu.rn: X 011 "1.\'.'0C::hl'"om.:i.J:;; mossambicw;) for maximum growth and maintenance were investigated in a clear water recirculating system utilizing a semi-purified diet. Taking individual fish as replicates, seven batches of fish of 34 g in average initial weight (small size group) were fed at different feeding rates (assigned rations: 0, 15, 20, 30, 35 g/kg body weight/d and ad libitum). Individual fish in big size group (average initial weight 71 g) were also fed in a similar fashion at assigned rates of 0, 10, 15, 20, 25 g/kg body weight/ct and ad libitwn. The functional relationship between various growth parameters and feed intake was investigated with the aid of regression analyses. There was a linear relationship between growth and feed intake of fish . The protein and energy requirements for maximum growth of fish group ranging from 33 78 g in weight was achieved with approximately 11.4 g protein/kg body weight /d with a corresponding metabolisable energy requirement of 449 KJ/kg body weight/d. The protein and energy requirements for fish ranging from 74 - 105 g in weight were 6.0 g protein /kg body weight/ct and 236 KJ/kg body weight/ct respectively. Regression analysis did not appear to be a reliable method for the determination of protein and energy requirement for maintenance as observed values depended upon the growth parameter used in the regression analysis . In the small size group, the protein requirement for maintenance ranged from 0.84 to 1 . 62 g protein/kg body weight/ct and the energy requirement ranged from 33 to 64 KJ/kg body weight/ct. In the big fish group the protein requirement ranged from 1 . 37 to 1.69 g protein/kg body weight/ct with corresponding energy requirement of 54 to 67 KJ/kg body weight/d. Suppression in fish growth of both groups was shown by feeding ad libitum, so that restricted ration should be applied to increase the production as well as to minimize the feed cost.