Comparative Evaluation of GIFT On-farm On-farm trials to compare the growth performance of GIFT with that of locally farmed tilapia strains were conducted in diverse agroecological zones in all five DEGITA
panicipating countries. The farming methods used
included ponds and cages with different levels of inputs (fertilizers
and feeds). Again, the results were very variable among and within
countries. For example, in farm ponds in Viet Nam and Bangladesh,
GIFT gave 33% and 78% higher yields, respectively, than those of local
tilapia strains. In cage farming in the PRC and the Philippines, GIFT
gave 25% and 54% higher yields, respectively, than those of local
strains (footnote 29). The GIFT used for these on-farm trials were
derived from only 2-4 generations of selection on the GIFT base
population in the Philippines. They were being compared across the
region with diverse farmed tilapia strains, all of which lacked a history
of sustained genetic improvement but which were also very variable
in quality. For example, the widely farmed chitralada strain in Thailand had
an excellent reputation and well-proven track record
among farmers and researchers, compared with those of local tilapxa
in Bangladesh. Moreover, some local tilapia strains would have had
some initial advantages over GIFT in terms of local adaptation.
Despite these complications, the on-farm trials indicated that GIFT
were sometimes significantly superior to, and in no cases significantly
inferior to, the locally farmed tllapia strain with which they were
compared. An analysis that accounted for heterogeneity of farm
environments and pracitces showed some statistically significant
higher average weights at harvest of GIFT and some higher survival of GIFT than
those of locally farmed tilapia strains(Table).