EFFECTS OF PINE POLLEN ON SEX REVERSAL AND GROWTH OF NILE TILAPIA Oreochromis niloticus LARVAE

Cherry T. Nian^{1, 2}* and Augusto E. Serrano, Jr.

1.) Institute of Aquaculture, University of the Philippines Visayas
Miagao, Iloilo, Philippines
2.) Mindanao State University Tawi-Tawi College of Technology and Oceanography
Sanga-Sanga, Bongao, Tawi-Tawi, Philippines
cherry_nian@yahoo.com

Early maturation and prolific breeding in culture systems are the major problems with tilapia breeding that results in overcrowding, decreased growth rate and low production. Monosex culture through hormonal sex reversal is seen as one of the most effective methods used to control overpopulation and possibly produce high yield. The experiment was carried out to investigate the effects of pollen from Pinus tabulaeformis (PP) as possible replacement for the synthetic 17-alpha-methyltestosterone (MT) in the Nile tilapia, Oreochromis niloticus larvae. The experiment evaluated the effects of PP on growth, feed conversion efficiency, survival and sex inversion as compared with that of the 17a-methyltestosterone (MT). Larvae were fed 5 diets containing graded levels of PP, namely, 0 (negative control), 80, 160, 320 and 640 mg kg^-1 and a positive control diet containing MT. The feeding trial lasted for 8 weeks.

Results showed that after 56 days of feeding, the MT diet resulted in all the Nile tilapia converted to male (100%) but was statistically similar with those of the PP diets (81.0% to 89.0% male, p<0.05). Almost half of the fish fed the control diet were male (50.5%) and almost half female (49.5%). Results of the growth trial showed that the final weight (FW) and weight gain (WG) of fish fed diets containing 0.08 g kg^-1 PP and 0.32 g PP kg^-1 were significantly higher than of those fed the MT diet (p<0.05). Feed intake (FI) of all experimental fish were statistically similar (p>0.05). The group fed 0.08 g PP kg^-1 diet exhibited significantly higher SGR than did the MT group. The MT group exhibited lower feed conversion efficiency (i.e. higher FCR) than did the control group. Those fed diets containing 0.08 and 0.32 g PP kg^-1 exhibited better FCR than those fed the MT diet. Survival ranged from 68% to 79% and were statistically similar in all the dietary treatments (p>0.05). In conclusion, PP could replace the MT in effecting sex reversal from female to male with statistically similar results; it could also promote better growth and feed conversion efficiency at the minimum dietary level of 0.08 g PP kg^-1.