Comparison of growth performance among the late selected generations of F13-F15 of NEW GIFT strain of Nile tilapia (Oreochromis niloticus)

Abstract:

Growth performance of NEW GIFT strain of Nile tilapia（Oreochromis niloticus）from F₁₃to F₁₅ was compared at Experimental Station for Fish Germplasm of Shanghai Ocean University for 67 days in 2011. The results showed that: (1) The body weights of F₁₃-F₁₅ at the end of the experiment were 195.7 g, 213.4 g, 218.3 g, respectively. Analysis of variance showed that growth rate of F₁₄ and F₁₅ was significantly faster than F₁₃(P<0.05), but no significant difference was detected between F₁₄ and F₁₅ (P=0.483); (2) The averages of daily body weight gain of F₁₃-F₁₅of the total experiment periods were 2.39 g/d, 2.61 g/d, 2.74 g/d respectively. F₁₅ was 4.98% higher than F₁₄, and F₁₄ was 9.21% higher than F₁₃.The average improvement of growth rate per generation was 7.10%. It could be considered that selection response to growth performance of F₁₃-F₁₅of NEW GIFT strain was about 7.10%; (3) The variation coefficients of body weight of F₁₃-F₁₅ were 6.33%, 4.87%, 1.60% respectively at the end of the experiment, namely F₁₃>F₁₄>F₁₅, which suggested that the variation coefficient decreased with selection progress. It is conjectured that genetic improvement of NEW GIFT strain never stopped in the course of continuous selection. The fixation of major gene controlling growth was in progress. There is a certain distance from the selection limit.