D. Lemos et al., Protein digestion in penaeid shrimp: digestive proteinases, proteinase inhibitors and feed digestibility, AQUACULTURE, 186(1-2), 2000, pp. 89-105
Protein is the most abundant ingredient in both natural and prepared diets
of penaeid shrimp. The assessment of protein digestion through the developm
ental stages of penaeids may contribute to the development of more suitable
feeding schedules for their cultivation. Among the techniques to study pro
tein digestion, detection and characterization of digestive proteinase inhi
bitors in proteinaceous feed ingredients can be achieved by substrate-[sodi
um dodecyl sulphate polyacrylamide gel electrophoresis] (SDS-PAGE). In vitr
o assays of protein digestibility are also useful tools when testing altern
ative protein sources in the formulation of shrimp feeds. The present artic
le reviews three methods that have been used to assess protein digestion: (
1) detection and characterization of proteinase activity and proteinaceous
proteinase inhibitors by substrate-SDS-PAGE, (2) quantification of proteina
se activity, and (3) in vitro evaluation of digestibility of dietary protei
n sources by shrimp proteinases. A compilation of previously reported and u
npublished data on some aspects of penaeid protein digestion is presented.
Trypsin activity of Litopenaeus schmitti varied considerably during larval
and postlarval development, showing the highest value at protozoea III. The
molecular weight of digestive proteinases from early stages of Farfantepen
aeus paulensis also differed from the adult pattern, and some activity band
s could be characterized as trypsin in adult F, paulensis. The digestive pr
oteinase pattern of adult Farfantepenaeus californiensis, F. paulensis, L.
schmitti and Litopenaeus vannamei in SDS-PAGE showed clear differences amon
g these species, which may be evidence of a species-specific pattern of pro
tein digestion. In vitro evaluation of digestibility of aquafeeds can be ac
hieved by the pH-stat method, which can help in the choice for alternative
protein sources. Moreover, the quality of postharvest shrimp may also be af
fected by increased digestive proteinase activity that seems to be stimulat
ed by low nutritional quality feeds. (C) 2000 Elsevier Science B.V. All rig
hts reserved.