Performance evaluation of Nile tilapia (Oreochromis niloticus) improved strains in Ghana

Growth performance and survival to harvest of the Akosombo strain generation 10 and the GIFT strain generation two (derived from GIFT generation 11 in Malaysia) were evaluated in Ghana. The fish were from 96 families of the Akosombo selected line (AKOS), 30 of the Akosombo control line (AKOC), and 22 of the GIFT strain (GIFT). In total, 11,812 tagged fingerlings were stocked at a density of 3 fish.m−2 into two ponds, each 2000 m2. Fish were fed 38% crude protein pelleted feed, twice daily at a rate of 5% body weight, for 120 days. Harvest weight of GIFT (150.1 ± 58.5 g) was 2.2 times larger than AKOC (67.6 ± 28.4 g) and 1.8 times larger than the AKOS (85.2 ± 32.0 g) strains. The least-squares mean weight of male GIFT were 98.6 g more than AKOC and 82.7 g more than AKOS. The corresponding ratios for females were even greater, with female GIFT weighing 106.5 g more than AKOC, and 89.9 g more than AKOS. The AKOS grew larger than the AKOC, 15.9 g larger for males and 16.6 g for females. All differences were highly significant (P < 0.001). Male fish were significantly larger than females for all three strains (P < 0.001). Overall, individual survival rate at harvest was 53.6% and not significantly different between strains, with GIFT survival being 55.2%, AKOS 54.5% and AKOC 50.0%. The results of the present study demonstrated: 1) marked differences in the growth performance of GIFT and Akosombo strains, and 2) the strong growth performance of GIFT in an equatorial West African environment, with similar survival to that of the local strain.