A 12-weeks feeding trial was conducted to evaluate the effects of encapsulated butyric acid (ButiPEARL ™ ) and microemulsified yellow carotenoid (Quantum GLO™ Y) on growth, immune parameters and their synergistic effect on pigmentation of hybrid catfish. In the experiment, the catfish was randomly divided into 12 groups of 15 fishes and then fed with four experimental diets containing 0.5 kg/t ButiPEARL™, 0.7 kg/t Quantum GLO™ Y, 0.5 kg/t ButiPEARL™ + 0.7 kg/t Quantum GLO™ Y, or none of these supplements (control diet). The results showed that the ButiPEARL™ + Quantum GLO™ Y fed group gave the highest yellowness (b*) score of 18.43 in the back muscle and almost double the total carotenoid measured in the fish muscle (151.35 mg/kg) compared to the Quantum™ Y fed group. This suggests that butyric acid in the diet had a synergistic effect on carotenoid absorption and pigmentation performance of catfish. The body weight of all treatment groups was significantly different from the control group and the catfish fed ButiPEARL™ alone had the highest body weight gained followed by the ButiPEARL™ + Quantum GLO™ Y fed group with an FCR improvement of 25 points and 13 points respectively over the control. There was no adverse effect on the immune system after feeding both butyric acid and carotenoid to the catfish and the immune parameters (number of leucocytes, erythrocyte, percent of hematocrit, haemoglobin and total protein) of ButiPEARL™ + Quantum GLO™ Y fed group were improved compared with the other groups. In conclusion, ButiPEARL™, Quantum GLO™ Y and the combination have positive effects on performance and pigmentation in catfish aquaculture.

We tested the feasibility and effect of including dietary carotenoids of different forms, microemulsified (MY) and non-microemuslified (NMY), in diets for hybrid catfish (Clarias macrocephalus × Clarias gariepinus). The results showed that the abdominal skin and back muscle yellowness (b *) of fish fed with 0.7 kg/t MY was higher than the other treatments (1.0 kg.t NMY and control) (p<0.05) with a score of 8.30 and 16.33 respectively. This group also gave the highest total carotenoid deposited in the muscle of 88.27 mg/kg. Carotenoid addition to the control diet at 1.0 kg/t NMY and 0.7 kg/t MY dosage have no adverse effect on the growth, in fact they helped to improve the body weight gain by 82.98 g and 84.17 g (p<0.05) with an FCR improvement of 13 points and 16 points (p<0.05) respectively. There was no adverse effect on the immune system after feeding carotenoid to the catfish and enhancement was observed in certain immune response indices when compared to the control. The findings in the present study were very significant because it supported that microemulsified yellow carotenoids (with smaller particle size of ~0.25 µm) and when used at lower inclusion rate of 30% could achieve better overall performance when compared to the regular size carotenoids and control due to its enhanced bioavailability.