Improvement of pellet quality with proteins recovered from whole fish using isoelectric solubilization-precipitation

Abstract

Muscle proteins are known to form thermally induced gel networks and may bind particles such as feed constituents. Dietary incorporation of functional proteins may improve pellet quality. Muscle proteins were recovered from rainbow trout by using isoelectric solubilization-precipitation. The objectives of this study were 1) to determine the proximate composition and amino acid content, AMEn, TMEn, and true amino acid digestibility of trout protein isolate and paste (TPP), and 2) to determine the effects of TPP on feed manufacturing, pellet quality, and true amino acid digestibility of broiler diets formulated to include TPP. Four treatments, consisting of 1) a control, 2) 5% TPP (HTPP), 3) 2.5% TPP (LTPP), and 4) 3.9% added moisture (MOIS), were manufactured at the West Virginia University pilot feed mill using a Latin square design. Five percent TPP had the highest pellet quality, followed by LTPP, MOIS, and the control. The improvement in pellet quality could be attributed to gelation of the recovered proteins. Addition of TPP reduced pellet mill production rate. Relative electrical energy usage decreased with MOIS but increased with HTPP relative to the control and LTPP treatments. Negative effects of increased viscosity likely associated with TPP were absent with LTPP. Digestibility of Asp, Glu, Pro, Ile, and Leu were lower for HTPP than the control. However, Ala digestibility was decreased in LTPP compared with the control. Therefore, fish muscle proteins incorporated at less than 5% of the diet may be beneficial to the broiler industry as a pellet binder and nutritive feed additive.