Fishmeal is the primary dietary protein source for many farmed fishes. The decrease in the supply of fishmeal relative to its demand has heightened research on alternative protein ingredients. Hemp protein meal (HPM), a by-product from the hemp processing plant, has been reported to contain 30 – 40% crude protein and very high polyunsaturated contents, depending on the variety of the hemp plant. Despite the prospect of HPM in the aquafeed industry, information on its nutritive values and utilization by cultured fish is unavailable. Therefore, evaluating HPM productivity in Florida pompano and Red drum becomes necessary in aquaculture.
This study investigated the effect of replacing fishmeal (control) with hemp protein meal on the survival and growth performances of Florida pompano and Red drum. We hypothesized that HPM would produce negative responses on survival, feed intake, feed efficiency, growth, and proximate compositions in both Florida pompano and Red drum. Seven isonitrogenous (40% CP) and iso-lipidic (10%) experimental diets were formulated. In a completely randomized design with the tank as the experimental unit, Florida pompano and Red drum fingerlings were stocked in a recirculating system to triplicate groups of 20 fish/tank and three tanks/diet. Fishes were carefully fed by hand three times daily for 68 and 63 d, respectively, and survival was monitored. Post-feeding trial samples of both fishes (tissues, blood, and gut contents) were collected to determine body indexes, proximate compositions, and growth performance.
Our results showed that HPM had no adverse effect on both fish, with the survival of Florida pompano and Red drum ranging from 85 – 100% and 90 -100%, respectively. However, the growth of both pompano and Red drum (Fig. 1) was significantly affected by replacing fishmeal with HPM (P<0.05). Increased levels of HPM without taurine reduced the fish weights, and taurine supplementation offset the negative weight responses (P<0.05). Results on proximate compositions, protein efficiency ratio, and amino acid compositions will be presented later.