A study of the digestive enzyme activities in scaleless carp (Gymnocypris przewalskii) on the Qinghai-Tibetan Plateau

Two experiments were conducted to study the digestive enzyme activities in scaleless carp (Gymnocypris przewalskii) on the Qinghai-Tibetan Plateau. In experiment 1, the distribution of digestive enzymes in various digestive organs of G. przewalskii (body weight: 118.24 +/- 9.48 g) was studied. Results showed that digestive enzyme specific activities in intestine were significantly higher than those in hepatopancreas (P < 0.05). In intestine, the highest levels of trypsin and chymotrypsin specific activities were found in foregut and hindgut, the highest levels of lipase and amylase specific activities were observed in foregut (P < 0.05). In experiment 2, temporal changes of the digestive enzyme specific activities after feeding were investigated in G. przewalskii (body weight: 305.32 +/- 28.78 g). Results showed that lipase and amylase specific activities in foregut approached maximum levels at 2 h after feeding and then decreased to the basic level at 6 h after feeding. The trypsin specific activities in foregut and hindgut reached the maximum levels at 2 h after feeding and then to the basic level at 8 h after feeding. In conclusion, as stomach-less fish, foregut of G. przewalskii contributed more to the nutrients digestion. The fish could digest nutrients (protein, fat and carbohydrate) efficiently. Thus, increasing in the amount of G. przewalskii resources could be achieved by improving nutritional state in artificial culture systems.