Digestive Enzyme Profiling in Different Life Cycle Stages of Rainbow Trout (Oncorhynchus mykiss, Walbaum 1792) from Kashmir Valley

Abstract

For most fish species, the digestive tract produces enzymes related to metabolism, digestion, absorption and assimilation of nutrients including proteins, lipids and carbohydrates. A total of 200 intestine samples of O. mykiss from the national trout fish farm, Kokernag were screened to estimate the enzyme profiles of fish from fry to broodstock stages. The highest trypsin activity was obtained in the fry stage (95 U/mg), followed by the yearling stage (80 U/mg). The lowest value was observed in table size stage (0.0098 U/mg). The ALP activity was highest in table size stage (85.16 U/mg) followed by yearling stage (39.72 U/mg) while the lowest was at fingerling stage (3.44 U/mg). The total lipase activity was maximum in table size stage (273.16 IU/L) and minimum in yearling stage (25. 38 IU/L). The total amylase activity was highest in yearling stage (208.24 IU/L), followed by fry (151.57 IU/L) and lowest in brood stage (1.73 IU/L). Better understanding of the enzymes in the digestive tract can lead to designing feeds for various life cycle stages of O. mykiss keeping in view of the prominent intestinal enzyme stage and will lead to better growth by proper utilization of nutrients which in turn, lead to improved production of trout fish.