Evaluation of Nutrient (Protein) – Organism (Fish) Relationship Using a Saturation Kinetic Model

Zainab Sa'ad Beiruti


The primary objective of this thesis was to demonstrate that the net nutrient (protein) deposition and weight gain as a function of nutrient (protein) intake fits the Saturation Kinetic Model and utilize the model parameters to describe and predict protein intake-deposition relationship.

Groups of Nile tilapia, Oreochromis niloticus, fry (0.01 g) and small fingerlings (0.15 g) were each separately fed twelve semi purified diets in triplicates to the fingerling and duplicate to the fry trial. Each test diet contains a percentage of protein. Protein levels were (0%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50% and 54%). Each group of fish was randomly assigned a test diet. Fingerlings were fed at a rate of 10% their body weight per day seven days a week for 8 weeks while the fry were fed at a rate of 25% of their body weight per day for 4 weeks. The mathematical model (the four parameter saturation kinetics) was used to analyze the relationships between dietary crude protein intake and each of growth rate and protein depositions.

It was found that tilapia protein-response (deposition) and weight gain as a result of feeding the test diets fit the saturation kinetic model. O. niloticus weight gain and net nutrient (crude protein) deposition were described as a function of the protein intake graphically and numerically. Maximum efficiency and protein requirements were calculated from the model for the fries and the small fingerlings. Dietary protein requirements for fry and fingerlings were calculated and compared to other estimation using different models techniques.