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Evaluation of growth performance testing methods for strain comparisons of Nile tilapia (Oreochromis niloticus)
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B. Toberrt al. /Aquaculture 137 (1995) 325-332
Evaluation of growth performance testing methods for strain comparisons of Nile tilapia ( Oreochromis niloticus) Ma. Jodecel C. Danting”, Ambekar E. Eknathb, Hans B. Bentsenc “National Freshwater Fisheries Technology Research Center, Bureau of Fisheries and Aquatic Resources, Munoz, Nueva Ecija, Philippines “International Centerfor Living Aquatic Resources Management (ICURM), Makati, Metro Manila, Philippines ‘Institute of Aquaculture Research (AKVAFORSK), Norway
Abstract Providing adequate replicates to minimize environmental variation is often a technical problem during evaluation of relative growth performance of different genetic groups or strains of fish. This paper reports on strain comparison using different testing methods: communal testing, separate testing in replicates, and separate testing with internal reference fish. Communal testing and separate testing are methods used for comparing genetic groups in the same and in separate culture units, respectively. Testing with an internal reference involves inclusion of a reference fish in all culture units to provide internal statistical control against which the growth of test strains are evaluated. The seven strains of Nile tilapia (Oreochromis niloticus) used in the study include three African strains Egypt, Ghana, Senegal, and four domesticated Asian farmed strains known in the Philippines as Israel, Singapore, Taiwan and Thailand. A pairwise mating of 25 breeding pairs from each strain was done in 1 m fine mesh hapas. Swim-up fry were collected, counted, weighed and reared in hapas until they reached a size of 3-5 g when they were tagged with fingerling Ploy tags red tilapia used as internal control were of the same age as the seven strains. The experiment was carried out for a duration of 90 days in hapas (4 m’) installed in earthen ponds. Stocking density was maintained at 50 individuals per hapa. In treatment (a) with internal control, 20 tagged, 20 untagged fingerlings and ten red tilapia for separate rearing were stocked, while for communal rearing it was six tagged fingerlings per strain and eight red tilapia. In treatment (b) using conventional method of replication, the cages for separate rearing were each stocked with 25 tagged and 25 untagged fingerlings per strain. The hapas for communal rearing were each stocked with seven tagged fingerlings per strain per cage. The results indicated signilicant differences (P
B. Toberrt al. /Aquaculture 137 (1995) 325-332
Evaluation of growth performance testing methods for strain comparisons of Nile tilapia ( Oreochromis niloticus) Ma. Jodecel C. Danting”, Ambekar E. Eknathb, Hans B. Bentsenc “National Freshwater Fisheries Technology Research Center, Bureau of Fisheries and Aquatic Resources, Munoz, Nueva Ecija, Philippines “International Centerfor Living Aquatic Resources Management (ICURM), Makati, Metro Manila, Philippines ‘Institute of Aquaculture Research (AKVAFORSK), Norway
Abstract Providing adequate replicates to minimize environmental variation is often a technical problem during evaluation of relative growth performance of different genetic groups or strains of fish. This paper reports on strain comparison using different testing methods: communal testing, separate testing in replicates, and separate testing with internal reference fish. Communal testing and separate testing are methods used for comparing genetic groups in the same and in separate culture units, respectively. Testing with an internal reference involves inclusion of a reference fish in all culture units to provide internal statistical control against which the growth of test strains are evaluated. The seven strains of Nile tilapia (Oreochromis niloticus) used in the study include three African strains Egypt, Ghana, Senegal, and four domesticated Asian farmed strains known in the Philippines as Israel, Singapore, Taiwan and Thailand. A pairwise mating of 25 breeding pairs from each strain was done in 1 m fine mesh hapas. Swim-up fry were collected, counted, weighed and reared in hapas until they reached a size of 3-5 g when they were tagged with fingerling Ploy tags red tilapia used as internal control were of the same age as the seven strains. The experiment was carried out for a duration of 90 days in hapas (4 m’) installed in earthen ponds. Stocking density was maintained at 50 individuals per hapa. In treatment (a) with internal control, 20 tagged, 20 untagged fingerlings and ten red tilapia for separate rearing were stocked, while for communal rearing it was six tagged fingerlings per strain and eight red tilapia. In treatment (b) using conventional method of replication, the cages for separate rearing were each stocked with 25 tagged and 25 untagged fingerlings per strain. The hapas for communal rearing were each stocked with seven tagged fingerlings per strain per cage. The results indicated signilicant differences (P