Feed Peas in diets for shrimp tilapia and milkfish - Northern Pulse ...

The results of the digestibility trial did not support the assumption of reduced protein availability from feedpea. In the present study, dietary crude protein digestibility values of the experimental diets were above80%. A comparison with the control diet supports the observation that pea protein is well digested bymilkfish. In fact, apparent protein digestibility value was superior with the partial inclusion (10% of dietaryprotein) of this plant material compared to the control without feed pea. Feed pea at this level may onlyshow marginal effects of anti-nutritional factors and limiting amino acids due to its relatively low content ofsuch compounds and its fairly good protein biological value for fish nutrition. Another consequence of usingfeed pea in place of soybean meal in the diet formulation for milkfish is the reduction of bread flour in dietscontaining high levels of feed pea. This is because of the higher carbohydrate content of feed peacompared to soybean meal. At this inclusion level, in practical conditions, feeding costs can be dramaticallydecreased.In general, feed pea meal proved to be an acceptable ingredient for consideration in practical diets forgrower stage production of milkfish. Future work showed be directed towards evaluating extruded peaproducts where pre-gelatinization of the starch would be possible, or testing various pea proteinconcentrates which have been processed to remove unwanted components such as fiber, tannin, etc.These products contain much higher protein levels that could be used to substitute increasing amounts offish meal in fish feed formulations. Further studies are needed to find out the maximum inclusion level offeed pea using other ingredient processing methods (e. g. dehulling, autoclaving, pressure cooking, proteinconcentrating, etc) and different types of pellet making (e. g. extrusion); in consideration of the effect ofthese processing methods on efficient utilization of essential nutrients by the fish.Previous experiments using cold-pressed pellets for Atlantic salmon suggested that 40% fish meal proteinreplacement with pea or lupin protein concentrate was feasible (Carter, 1998). Carter and Hauler (2000)confirmed that at least 33% fish meal protein replacement with pea protein concentrate was possible. Amajor problem in the use of plant meals is their relatively low protein content. In the study of Carter andHauler (2000), the protein concentrates used were produced by air separation and resulted in lupin and peaconcentrates with 46% and 49% crude protein, respectively. This represented an increase of between 44and 133% over the protein in the raw lupin and peas, respectively. Protein at this level is comparable tosoybean meal, but still far lower than that in fish meal. Gouveia et al., (1993) compared the efficacy of threelegume seed meals, e. g., lupin seed meal (Lupinus albus), faba beans (V. faba) and pea seed meal (P.sativum) in a 3-month feeding trial with juvenile rainbow trout. They reported that trout performed well ondiets that had up to 20% of the protein content being supplied by each of these ingredients. In fact, growthand feed utilization was superior with the partial inclusion of these plant materials. The inclusion of a coextrudedplant protein made from rapeseed and field pea had no effect at up to 15% replacement of theprotein. However, at 45% inclusion, growth performance of rainbow trout was significantly lower than thecontrol diet (Gomes et al., 1993). The low digestible energy from both raw and autoclaved field peas waspredicted to limit their use in rainbow trout feeds (Pfeffer et al., 1995; Gouveia and Davies, 1998). Energydigestibility of legumes is considerably lower than for protein due to their high carbohydrate content. Theuse of extrusion is important in increasing the nutrient availability of plant meals, especially in relation toincreasing the amount of digestible energy available through greater gelatinization of starch (Pongmaneeratand Watanabe, 1993).Since the objective of this study was to evaluate the direct nutritive value of feed peas, the experiment wascarried out in an in-door clear water flow-through system. However, experience shows that milkfish inponds grow better than milkfish given the same feed under controlled laboratory conditions (Sumagaysay etal., 1991; Sumagaysay and Borlongan, 1995). It is expected that higher growth rates and better FCR andPER may result if the milkfish are reared in ponds. It is recommended that feeding experiments using thebest diets be done under natural pond conditions and an economic assessment of the feed pea-basedfeeds be conducted.23