Lysine Requirement For Different Strains Of Tilapia Oreochromis Tanganicae

Abstract

The optimal dietary Lysine (Lys) levels for two strains of juvenile Oreochromis tanganicae, an important component of fish nutrition for growth and maintenance, was studied. Both a Lake Tanganyika strain (T-strain) and a locally bred strain from the Misamfu Research Centre (MRC-strain) in Zambia were used to determine the lysine (Lys) requirements that maximized growth and survival. A factorial experimental design was used, incorporating two factors: three dietary Lys levels (1.13, 1.30, and 1.64% of the feed and the control designated as diet zero with no lysine inclusion) and the two different fish strains. Juvenile fish (50grams) from each strain were assigned to these diets and fed accordingly over a period of 60 days. This allowed for the assessment of the individual and interactive effects of Lys levels and fish strain on growth and health parameters. Various growth performance metrics, including final body weight, weight gain, specific growth rate, feed conversion ratio, and survival rate, were measured. Body composition analysis was done to understand the impact of dietary Lys on the fish's physiological makeup. The varying dietary Lys levels did not have a statistically significant effect on the growth parameters or survival rates of either fish strain. This suggests that within the range tested, Lys was not the limiting factor for growth. However, there was significantly lower ash content in the MRC strain group that fed the lowest Lys level. This difference, while potentially influenced by overall diet composition, warrants further investigation to understand its implications for bon mineralization and overall fish health. Although not statistically significant (P ≥ 0.05), a slight improvement in growth performance was noted in the groups fed the highest level of dietary Lys. While this trend did not reach statistical significance within the study's power, it suggests that higher Lys levels might offer a marginal benefit, especially if the experimental duration were longer or the number of replicates larger. By understanding the Lys requirements, aquaculture producers can formulate more efficient and cost-effective feeds, potentially leading to reduced production costs and increased overall aquaculture productivity.