Impact of dietary Quillaja saponins on growth, sex ratio and reproduction of Nile tilapia Oreochromis niloticus under field conditions in Bangladesh
- Publikations-Art
- Arbeitspapier/Diskussionspapier
- Autoren
- Steinbronn S., Hossain A., Francis G., Focken U. and Becker K.
- Erscheinungsjahr
- 2004
- Tagungsname
- 7th Asian Fisheries Forum, November 2004
- Tagungsort
- Penang, Malaysia
Tilapia aquaculture research focuses on environmentally friendly techniques to improve growth performance and to reduce uncontrolled reproduction lately. It was shown in laboratory experiments that a supplementation of the diet with Quillaja saponins resulted in increased growth, and suppression of reproduction in adult tilapia and a higher proportion of male fish in tilapia larvae. These findings were tested under field conditions in Bangladesh during a 4-month experiment.
Ten day old tilapia larvae were divided into four feeding groups and their diets supplemented with different doses of Quillaja saponins (QS) for five weeks. The treatments were control (no supplementation) and three groups fed diets supplemented with QS at 150 ppm, 500 ppm and 2000 ppm. After 5 weeks the fish were grown-out in hapas in a pond and fed a standard diet without saponins.
At the end of the experiment, the final body weight, weight gain, Specific Growth Rate (SGR) and the assimilation of nutrients in the group supplemented with 150 ppm QS were higher compared to the control, even though the differences were not statistically significant. The SGR and weight gain of tilapia fed diets supplemented with 500 and 2000 ppm QS were similar to the control. Food conversion efficiency was higher in all treated fish compared to the control group. The sex ratios in those fish supplemented with 150 and 500 ppm QS did not differ significantly from 50:50, but the share of males was slightly higher in both treatments compared to the control group. Fish in these groups produced normal fry. Fish whose diets were supplemented with 2000 ppm QS, did not reproduce at all. This could have been caused by a sterility of either males or females. Supplementation of the diet with QS could potentially be used for control of reproduction in tilapia.