Evaluation of Three In Vitro Enzyme Assays for Estimating Protein Digestibility in the Pacific White Shrimp Penaeus vannamei¹

Abstract

Abstract— In vitro enzyme assays are rapid, inexpensive techniques for estimating protein digestibility of feed ingredients. Three assays—the Lazo single‐enzyme assay with porcine trypsin; the Hsu multi‐enzyme assay with porcine trypsin, α‐chymotrypsin, and peptidase; and the Satterlee multi‐enzyme assay with porcine trypsin, α‐chymotrypsin, peptidase, and bacterial protease—were used to estimate relative protein digestibility (RPD) of selected feed ingredients used in diets for the Pacific white shrimp Penaeus vannamei. Ingredients tested were casein, gelatin, rice bran, shrimp meal, soybean meal, wheat gluten, and six varieties of fish meal. A highly significant, inverse, linear relationship existed between final pH in each of the enzyme assays and in vivo apparent protein digestibility of the ingredient in P. vannamei feeding trials. Ranking of RPD coefficients obtained in the Lazo single‐enzyme assay followed closely the ranking of published in vivo apparent protein digestibility coefficients for the same ingredients in P. vannamei digestibility trials. Results indicated that a single‐enzyme assay with porcine trypsin identified differences in protein digestibility of feedstuffs in vitro as well as the two multi‐enzyme assays tested. The porcine‐trypsin, single‐enzyme assay appears to be a potentially useful tool for evaluating protein quality and relative protein digestibility of feedstuffs for P. vannamei.

In vivo and in vitro protein digestibility of formulated feeds for Artemesia longinaris (Crustacea, Penaeidae)

“…The in vitro methods have been applied to the study of digestibility in crustacean (Lan and Pan, 1993;Ezquerra et al, 1997;Lazo et al, 1998). Such methods have potential as screening devices for determining the suitability of feed ingredients for shrimp feeds.…”

“…However, digestibility in vivo data are needed to validate data obtained in the digestibility in vitro (Ezquerra et al, 1997). In vivo and in vitro assays must correlate well to predict protein quality (Ezquerra et al, 1997;Lazo et al, 1998).…”

Species specific in vitro protein digestion (pH-stat) for fish: method development and application for juvenile rainbow trout (Oncorhynchus mykiss), cobia (Rachycentron canadum), and Nile tilapia (Oreochromis niloticus)

“…This motivated the development of in vitro methods based on the digestion of small amounts of feedstuff samples. Reported in vitro protein digestion methods include the use of digestive enzymes that may be available from commercial sources (Lazo et al, 1998;Shipton and Britz, 2002;Tonheim et al, 2007) or recovered from the target species Ezquerra et al, 1998;Tibbetts et al, 2011a). Nevertheless, different results in the in vitro digestion have been found depending on the enzyme origin, suggesting a species-specific feature of in vitro protein digestion (Ezquerra et al, 1998;Lemos and Nunes, 2008;Moyano and Savoie, 2001).…”

Effects of protease enzyme supplementation on protein digestibility of legume and/or fish meal-based fish feeds

“…A graph of pH values for enzyme-casein substrate was plotted against pH values of the enzyme -diet substrate and the slope of the graph used as the rate of pH change with time ( Figure 1). The rapid protein digestibility (RPD) was calculated as the ratio of percentage of pH change (-∆ pH) in the enzyme-diet substrate to pH change of enzyme-casein substrate following a formula adapted from that of (Lazo, 1994) as:…”