Milkfish is one of the most intensively cultured fish species in the Philippines. However, intensive fish culture is associated with chemical, biological, and physical disturbance that could lower the immune system of the fish leaving the fish vulnerable to diseases. Pollen of pine trees are sometimes used as a dietary supplement for animals due to its anabolic function which can increase growth rate. The present study aimed to determine the effects of various levels of dietary pine pollen from Pinus tabulaeformis Carr. on the growth and immune response of milkfish fry (Chanos chanos).
Milkfish fry with average body weight of 0.02 g were stocked in 15, 50L tanks at 40 fish per tank. A control diet (without pine pollen) and four experimental diets were prepared containing pine pollen at 0, 1.3, 2.6, 3.8, and 5.1 g kg-1, and fed to the experimental fish for 60 days. At the termination of the trial, milkfish were subjected to sublethal dosage of ammonia to test the immune response of the fish.
Results revealed that there was no significant difference on survival rates among dietary treatments (p>0.05). Milkfish fed with diets containing different levels of pine pollen exhibited significantly higher growth (p < 0.05) in terms of weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio than did those fed the control diet. This could be attributed to the anabolic and androgenic effects of androgen from the pollen. Survival rate of milkfish fed with the diets containing 2.6 to 5.1 g kg-1 pine pollen were significantly higher (p <0 .05) than those fed with diets containing 1.3 g kg-1 or with the control diet. The results indicated that diets incorporated with pine pollen could enhance the immune system of milkfish. Optimum dietary PP level was estimated using the quadratic model by using SGR and FCR values and found to be 3.0 g kg-1. In conclusion, pine pollen can be used as a dietary additive in milkfish diet to enhance growth and immune response against environmental stressors like dissolved ammonia.