Enhancing feed palatability and intake of low fishmeal diets
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by Phileo by Lesaffre
ishmeal is considered the best source of nutrients for aquaculture feeds due to the balanced nutrient composition and the high digestibility of its ingredients. However, the continuous depletion of fish stocks recorded worldwide, together with increased aquaculture production, is causing a shortage of fishmeal supply for the aquaculture industry. As an immediate consequence, the price of fishmeal has spiked, which is putting the profitability of shrimp aquaculture production at risk. It is, therefore, imperative that producers identify alternative protein sources that allow for an environmentally sustainable and economically viable shrimp production. Protein sources of vegetable origin are a valid alternative to partially replace fishmeal. Plant-based ingredients are largely available, economically advantageous when compared to fishmeal, and they have a good nutritional value. However, some features of vegetable materials make the transition from fishmeal to plant-based ingredients quite problematic. Ingredients of vegetable origin often contain anti-nutritional factors (ANFs), which are biological compounds such as tannins, saponins, and glycoalkaloids that are naturally produced by plants to defeat predators in their natural environment. These compounds have a bitter taste and, therefore, result in a reduced acceptability and palatability of the feed. Moreover, shrimps are able to detect the feed in the water thanks to the presence of chemical signals present in fishmeal, such as amino acids, small peptides, amines and nucleotides, that attract them. Reducing the quantity of such key biochemical triggers through the partial substitution of fishmeal level with plant-based ingredients in aquafeeds negatively affects attractiveness of the feed and, consequently, reduces the feed intake. Ultimately, decreased feed palatability and feed intake have a dramatic effect on shrimp growth performance, which, in turn, severely hinder productivity and economic viability.
A biological solution to address the pitfalls of low fishmeal diets
Prosaf feed additive is a premium yeast-based product developed by Phileo by Lesaffre. It comprises a yeast fraction
obtained from the primary culture of a proprietary Saccharomyces cerevisiae baker’s yeast strain. Prosaf® is produced through a scientifically-validated biotechnological process that autolyses the yeasts using thermal treatment and subsequently centrifuging them to separate the cell content from the cell wall. The latter component is discarded,
Figure 1: Impact of Prosaf® on feed intake. Four diets were tested in form of extruded pellets: 1. High fishmeal formula (12% fishmeal), 2. low fishmeal formula (3% fishmeal), low fishmeal with 2% squid meal, and low fishmeal with 2% Prosaf®. Whiteleg shrimps (Litopenaseus vannamei) with an average 13g body weight were placed in tanks at a density of 80 shrimps per tank (140 shrimp/m2). Shrimps were feed twice a day for 15 days. One hour after feed distribution, leftovers of each feed were weighted to calculate feed consumption. The position of the feeding trays changed daily. The feeding trials for each combination of test diets were carried out in quadruplicates. Different letters above each bar indicate statistically significant differences (paired Student’s t-test, p <0.01. A) Schematic representation of the tanks with the two feeding trays. B) Comparison between 12% fishmeal diet and 3% fishmeal diet. C) Comparison between 3% fishmeal diet and 3% fishmeal diet with 2% squid meal. D) Comparison between 3% fishmeal diet and 3% fishmeal diet supplemented with 2% Prosaf® (Source: Phileo by Lesaffre)
24 | August 2019 - International Aquafeed