Jp. Lazo et al., Evaluation of three in vitro enzyme assays for estimating protein digestibility in the Pacific white shrimp Penaeus vannamei, J WORLD A C, 29(4), 1998, pp. 441-450
In vitro enzyme assays are rapid, inexpensive techniques for estimating pro
tein digestibility of feed ingredients. Three assays-the I,azo single-enzym
e assay with porcine trypsin; the Hsu multi-enzyme assay with porcine tryps
in, cu-chymotrypsin, and peptidase; and the Satterlee multi-enzyme assay wi
th porcine trypsin, ol-chymotrypsin, peptidase, and bacterial protease-were
used to estimate relative protein digestibility (RPD) of selected feed ing
redients used in diets for the Pacific white shrimp Penaeus vannamei. Ingre
dients tested were casein, gelatin, rice bran, shrimp meal, soybean meal, w
heat 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. vanname
i feeding trials. Ranking of RPD coefficients obtained in, the Late single-
enzyme assay followed closely the ranking of published in vivo apparent pro
tein digestibility coefficients for the same ingredients in P. vannamei dig
estibility trials. Results indicated that a single-enzyme assay with porcin
e trypsin identified differences in protein digestibility of feedstuffs in
vitro as well as the two multi-enzyme assays tested. The porcine-trypsin, s
ingle-enzyme assay appears to he a potentially useful tool for evaluating p
rotein quality and relative protein digestibility of feedstuffs for P. vann
amei.