Changes of digestive enzymes activity in Caspian kutum (Rutilus frisii kutum) during larval developmental stages

The ontogenesis and specific activities of pancreatic (trypsin, chymotrypsin, amylase and lipase) and intestinal enzymes (alkaline phosphatase, aminopeptidase N) were investigated in kutum (Rutilus frisii Kutum) from the onset of exogenous feeding (3 day after hatching, DAH) to the juvenile stage at 50 DAH. Trypsin- and chymotrypsin-specific activity showed similar patterns and increased with larval development and age. After the first feeding, specific activity of amylase and lipase increased and reached a peak at 10 DAH, followed by a sharp decrease until 25 DAH, after which it is increased again. Carbohydrate and lipid content changes in diet have led to fluctuations (increases or decreases) in amylase and lipase activities. Alkaline phosphatase and aminopeptidase N specific activity had similar patterns and showed increased trend with age. Sharp increases in activity for both enzymes from 7-10 DAH indicated maturation of the enterocytes and the achievement of adult-like mode of digestion. Our results suggest that kutum is capable of digesting protein, lipid and carbohydrates at early stages of growth. However, due to low level of lipase-specific activity compared to other enzymes, it seems that kutum larvae prefer diets containing higher protein levels than diets with higher lipid content. Therefore, for this species lipid component should remain at low level in formulated diets. In this study, specific activity of most digestive enzymes exhibited a sharp increase when co-feeding on rotifers and formulated diet started from 7-10 DAH. The increase in activities of pancreatic and intestinal enzymes in this period can be due to maturation of exocrine pancreas and brush border enterocytes, respectively and showed that this fish has ability to digest formulated diets

Changes of digestive enzymes activity in common carp (Cyprinus carpio) during larval ontogeny

This study was aimed to gain knowledge on the ontogeny of digestive enzymes in common carp larvae at the governmental Warm Water Fish Aquaculture Center of Shahid Rajaee in Sari, Mazandaran, Iran. The ontogenetic development of pancreatic (trypsin, chymotrypsin, lipase and α-amylase) and intestinal (alkaline phosphatase and aminopeptidase-N) enzymes were assessed in common carp larvae from first feeding (3 days post hatching) to 33 days post hatching (dph). The larvae started to feed on rotifers at day 3 to day 7. Feeding on a commercial diet was started from day-8 onwards. Specific trypsin and chymotrypsin activities feed with rotifer were 0.011 U/mg protein and 0.003 U/mg protein at day 7, respectively; then the specific activities feed with dry food reached a maximum level at 33 dph (0.028 U/mg protein and 0.028 U/mg protein, respectively) (P<0.05) compared to live prey. The elevated alkaline proteases activity can be related to adaptation of larvae to digest protein content in the food. Specific lipase activity was 0.0006 U/mg protein at 7 dph; then the activity feed with dry food reached a maximum level at 15 dph (0.0011 U/mg protein) (P<0.05) compared to live prey. Specific α-amylase activity feed with rotifer was 85.86 U/mg protein on the 7 dph; consequently, its specific activity reached a maximum level at 15 dph (128.77 U/mg protein) (P<0.05). Specific alkaline phosphatase and aminopeptidase N activities feed with rotifer were 6 U/mg protein and 0.0106 U/mg protein at day 7, respectively; then the specific activities feed with dry food reached a maximum level at 33 dph (28.66 U/mg protein and 0.58 U/mg protein, respectively) (P<0.05) compared to live prey

Changes in growth and amino acid composition of Rutilus frisii kutum during larval development

The present study investigated changes in growth and amino acid composition Kutum Rutilus frisii kutum during larval development. For this purpose, the periodic sampling from larvae obtained from breeders propagation was carried out at the fish aquaculture center of Shahid Rajaee in Sari. The samples were obtained at 1, 3, 7, 10, 15, 20, 25, 30, 35, 40 and 50 days after hatching (DAH). The result of larvae growth showed that mean initial and final length of Kutum (1 DAH, 50 DAH) were 8.47±0.02mm and 35.34±0.41mm, respectively. Initial and final weights were 4.02±0.01mg and 483.33±1.11mg, respectively. The composition of total amino acids of Kutum larvae changed significantly during ontogeny. High correlations were found between rotifers and dry food but correlations dry food was higher than that rotifer. No major imbalance was found in essential amino acids profile of the diet of fish larvae. Nevertheless, low correlation of rotifer to dry food in rotifer AA nutritional balances was less than dry food. During this study, methionine, lysine, arginine, threonine and histidine appeared to be limiting amino acids. These fatty acids showed the significant difference between the amino acid profile in larva and the diet

Histology of intestine and fatty acid profile of Pacific white shrimp (Litopenaeus vannamei) effected by dietary inulin

The effects of inulin were studied on the growth indices, intestinal morphology as well as fatty acid profile of the Pacific white shrimp, Litopenaeus vannamei with average weight 3.21±0.03 g for 5 weeks. The experiment was carried in triplicate, was conducted in circular PVC tanks of 300 L capacity with 25 shrimp per tank at the Aquaculture Center (Delvar, Bushehr province). Inulin was added to the diets at a 2 levels (0 and 2 percent). The shrimp were fed the experimental diets to visual satiety five times a day at 08:00, 12:00, 16:00, 20:00 and 24:00 h. No significant differences in growth performances (such as survival, feed conversion ratio (FCR), specific growth rate (SGR), Protein efficiency ratio (PER)) was observed, however, Dietary inulin brought about significantly improved 20:3n3 fatty acid content between the two treatments (P>0.05). Intestine epithelium cells height in the abdominal sections significantly (P< 0.05) were higher in shrimp fed by dietary inulin. The results of this study showed that supplement of 2% of inulin has positive effects on fatty acid profile and intestinal morphology in Litopenaeus vannamei