EFFECTS OF HUMIC ACID ADDITION TO FEEDS WITH HEAVY METAL CADMIUM CONTAMINATION FROM GREEN MUSSELS ON THE GROWTH PERFORMANCE OF ASIAN SEABASS

Abstract

Although it contains heavy metals, the highly nutritious green mussel Perna viridis is used as a fish meal replacement in fish diet. Fortunately, humic acid (HA) has the ability to chelate heavy metals in animal feeds. Its addition in fish feed formulation is, therefore, needed to prevent the accumulation of heavy metals in the fish body. Hence, an experiment using the Completely Randomized Design (CRD) with 5 treatments and 3 replications was conducted to evaluate the performance and feed efficiency of Asian seabass Lates calcarifer juveniles on the addition of HA on its green mussel diet containing heavy metal cadmium (Cd).  Five experimental diets were formulated with different dosages of HA addition at 0, 400, 800, 1200, and 1600 mg Kg^-1of feed as treatments A, B, C, D and E, respectively. The experimental diets were given to triplicate group of 15 Asian seabass juveniles with initial body weights of 4.30 ± 0.60 g in a 70-day cultivation period of feeding until satiation. The results showed that feed comsumption, feed digestibility, protein retention, growth performance and feed eficiency were significantly affected by HA addition in the fish diet. Among all treatments, HA addition of 1600 mgKg^-1 produced the best biological response from the Asian Seabass. This indicated that the humic acid addition in the diet formulation can improve the utilization of feed for fish growth. The heavy metal cadmium (Cd) in the flesh of Asian seabass is still under the limit set in the food safety standard, hence, the fishes are still considered safe for human consumption. Therefore, the green mussel meal, with HA addition as an alternative source of protein, has potential as feed additive for the diet contaminated Cd of Asian seabass juveniles.