Investigation of Selective Breeding Gains for Growth Rate in Nile Tilapia at the National Institute for Freshwater Fisheries Research, Niger State

Selective breeding programmes for improved growth rate in Nile tilapia offer the potential to substantially increase the productivity and profitability of tilapia aquaculture in Nigeria, yet genetic gain estimates from structured selection programmes under Nigerian hatchery conditions have not been published. This study investigates selective breeding responses for growth rate in Nile tilapia over two selection generations conducted at the National Institute for Freshwater Fisheries Research, New Bussa, Niger State. Breeding values for body weight at 180 days post-hatch were estimated using BLUP individual animal models incorporating pedigree data from 1,200 full- and half-sibling families. Selection differentials and realised heritability were calculated from parent-offspring regression and comparison of selected versus control line growth. A control line maintained by random mating alongside the selected line provided the reference for estimating genetic gains. Results showed that heritability of body weight at 180 days was 0.32, indicating moderate additive genetic variation available for selection. After two generations of selection, the selected line showed a cumulative genetic gain of 18.4% in body weight compared to the control line. Feed conversion ratio improved by 12.3% in the selected line, attributed to correlated selection response. The study demonstrates the feasibility and magnitude of genetic improvement achievable in Nigerian tilapia through structured family selection and recommends the expansion of the selection programme to incorporate at least one commercial partner farm for genetic gain validation under production conditions.

Keywords: selective breeding, Oreochromis niloticus, genetic gain, heritability, NIFFER