Litopenaeus vannamei digestive metallo peptidases compensate for anti-nutritional SBTI in feed

The aim of this work was to study mechanisms of homeostasis of the digestive system of the whiteleg shrimp Litopenaeus vannamei when fed anti-nutritional soybean trypsin inhibitor (SBTI). In a previous work, we tested if the shrimp could respond against SBTI in feed with the increase in the digestive proteolytic activity. This time we tested the time of response against the inhibitor and also how the two major digestive trypsin phenotypes change the proteolytic activity. In groups fed SBTI, the total proteolytic activity, trypsin and chymotrypsin decreased during food transit time (2-4 h), but increased at 23 h postprandial. Three metallo peptidases absent in the control group were identified in groups fed SBTI; individuals with trypsin phenotype CBA increased the activity of two metallo peptidases at 4 h of SBTI ingestion, while, individuals with trypsin phenotype CB increased the activity of three metallo peptidases at 23 h postprandial. The first evidence of feedback by the digestive system in the whiteleg shrimp fed SBTI was 1 h postprandial, with a concomitant increased in metallo peptidases activity at 4 h or 23 h depending on the trypsin phenotype in each specimen.