Evaluation of growth performance and nutritional quality of diets using digestive enzyme markers and in vitro digestibility in Siamese fighting fish (Betta splendens Regan, 1910)

Digestive enzymes and their effects on in vitro digestibility of feeds and feedstuffs, as well as on growth performance quality were studied in Siamese fighting fish (Betta splendens Regan, 1910). The specific activities of total protease, amylase, trypsin and chymotrypsin increased during development and were higher in females than in males at maturation (P < 0.05). The activity ratio of trypsin to chymotrypsin corresponded to fish growth, and showed lower values in females than in males. White muscle levels of RNA decreased during development, with females having higher levels than males, while the protein levels increased with no difference between sexes. In the oocytes, trypsin-like and chymotrypsin-like specific activities were very low, and the concentrations of RNA, protein and protein/lipid ratio were higher than in the muscle. For in vitro digestibility, wheat gluten, soybean meal and fish meal were among good protein sources while the meals from peanut, fish and soybean were good carbohydrate sources. Golden apple snail meat was a good source for both protein and carbohydrate. The crude enzyme extracts from different growth stages and sexes had different abilities to digest the same feeds and feedstuffs. This will make it possible to preliminarily study the authenticated nutritional quality of raw materials for future feed formulations for B. splendens.Keywords: Betta splendens, digestive enzymes, feedstuff, in vitro digestibility, muscle quality, oocyte quality, Siamese fighting fishAfrican Journal of Biotechnology Vol. 12(14), pp. 1689-170

Intermittent feeding induces compensatory growth of juvenile yellow mystus (

Cyclical starvation and refeeding in order to induce compensatory growth were investigated in juvenile yellow mystus (Hemibagrus nemurus). The fish (7.12 ± 0.14 g initial body weight and 8.87 ± 0.04 cm initial length) were starved for one (1DPW), two (2DPW), three (3DPW) or four (4DPW) days per week and otherwise fed ad libitum, while the control group was fed every day (no starvation, 0DPW). The indoor experiments lasted six weeks and followed a completely randomized design (5 treatments × 3 replications × 10 fish per replication). Growth performance, feed utilization, specific activity of digestive enzymes, carcass composition and muscle quality were used to compare the treatment effects. The fish in the 3DPW group exhibited clear compensation for the reduced number of feeding days and had increased body weight towards the end of the experiment. However, this compensation was insufficient to match the specific growth rate in the control group that was fed to satiation daily. The 3DPW treatment also maintained feed utilization parameters, specific activities of protein-, carbohydrate- and lipid-digesting enzymes, carcass composition and muscle quality, relative to the 0DPW control group. The remaining treatments gave some inferior characteristics when compared to 3DPW and 0DPW; the ranking of these feeding treatments was unexpected within the studied period. These findings suggest that cyclical starvation for three days per week (3DPW treatment) and refeeding could be used for rearing juvenile yellow mystus. The intermittent feeding schedule scheme is useful for labor management in the aquaculture production of yellow mystus. However, since partial compensatory growth was observed in the 2DPW and 4DPW groups, as indicated by the compensation coefficient, prolonged experiments on the accelerated growth rate should be conducted in further studies

Characterization and expression levels of protease enzymes at different developmental stages of Siamese fighting fish (Betta splendens Regan, 1910)

Characterization of total proteases, trypsin and chymotrypsin were performed at pH 2 12 and temperatures 20-80°C in three life stages of Siamese fighting fish (Betta splendens Regan, 1910). At least fourteen protease activities were detected, including seven acidic (pH levels 2, 4 and 5-6), one neutral (pH 7), and six alkaline (pH levels 8-12) activities in the optimal temperature range of 30-60°C. The neutral and alkaline pH profiles were different between sexes during the on-growing stage (1.5 month-old). The acidic proteases played a major role in digestion in the early life stage (10-day-old), while the alkaline proteases became more important toward older stages. Trypsin and chymotrypsin showed similar characteristics with at least five activities observed. For trypsin, activity was detected with pH 7 and 8 at 50°C, and pH 10 at 30, 50 and 60°C. For chymotrypsin, activity was found at pH levels 7 and 8 at 50°C, and pH 10 at 30, 40 and 50°C. Regardless of sex and age, the most suitable conditions for studying digestive enzyme activities in general were at pH 8 and 50°C for total proteases, pH 7-8 and 50°C or pH 10 and 30-35°C for trypsin and pH 7-8 and 50°C or pH 10 and 40°C for chymotrypsin. Trypsin and chymotrypsin are important proteases showing similar general optimal conditions to that of total proteases. This information provides elementary knowledge for studying protein digestibility by in vitro techniques and for determining growth performance quality using digestive enzyme markers in Siamese fighting fish

Temperature and pH Characteristics of Amylase and Lipase at different developmental stages of Siamese fighting fish (Betta splendens Regan, 1910)

Temperature (20-80°C) and pH (2-12) profiles of amylase and lipase at three stages (10-dayold, 1.5-month-old and 3-month-old) in Siamese fighting fish Betta splendens Regan, 1910) were studied. At least nine amylase activities were observed during development: pH 7 at 40°C, pH 9 at 30°C and 50° C, pH 8 and pH 11 at 50°C in females and pH 8 and pH 11 at 40°C and 60°C in males. At the younger stage (≤ 1.5 month old), activity at pH 7 and 40°C, and at pH 9 and 30°C and 50°C was observed. At the older stage (≥ 1.5 month old), amylase activity at pH 8 and pH 11 in the temperature range of 40-60°C was found. Lipase had at least five levels of activity: pH 7 at 20°C and 40°C, pH 8 at 20-40°C and 60°C, and at pH 11, where the activity peak disappeared in the maturing stage (3 month old) in both sexes. Amylase had very low specific activity at the 10-day-old stage, while lipase had a high specific activity, similar to older stages. The most suitable pH to determine amylase and lipase activity in Siamese fighting fish was pH 8, whereas a temperature of 50°C was appropriate for amylase and 40°C was suitable for lipase, regardless of sex and age. This information is a prerequisite for future studies of the in vitro digestibility evaluation of nutrient utilization in Siamese fighting fish

Effects of different modified diets on growth, digestive enzyme activities and muscle compositions in juvenile Siamese fighting fish (Betta splendens Regan, 1910)

The effects of four modified diets (gamma-irradiated, microwave-irradiated, probiotic-supplemented and carbohydrase-supplemented diets) were studied on digestive enzyme specific activities and growth performance quality of juvenile Siamese fighting fish (Betta splendens Regan, 1910) during 2 weeks of critical and intensive rearing period. The modified procedures did not change biochemical compositions and gross energy of diets, but generally resulted in relatively higher in vitro digestibilities of protein and carbohydrate and fish survival rate, albeit insignificant. Only gamma irradiation significantly increased in vitro protein digestibility of the diet, and microwave irradiation increased starch gelatinization and water solubility (Pb0.05). Fish fed microwave-treated diet showed highest values in all studied growth indicators and digestive enzyme specific activities (except lipase), with significantly higher amylase specific activity and activity ratio of amylase to trypsin (A/T ratio). Correlation analysis indicated significant relationships (Pb0.05) among the levels of total protease, amylase and trypsin, and between SGR and A/T ratio. Muscle and body compositions of juveniles fed on microwave- or gamma-irradiated diets were similar to the control, while the juveniles fed on probiotic- or carbohydrase-supplemented diets showed lower protein depositions (Pb0.05). Similar levels of RNA, RNA/Protein ratio, and Protein/Lipid ratio in body andmuscle in all dietary groups fed ad libitumsuggested that the improved growth performance in juvenile Siamese fighting fish fed on microwave-irradiated diet may not be only due to improved physicochemical properties of the diet but also improved fish consumption rate

Ontogenetic development of digestive enzymes and in vitro digestibility of spotted Babylon (Babylonia areolata) veligers

The ontogenetic development of the main digestive enzymes and in vitro digestibility were investigated in spotted Babylon (Babylonia areolata) veligers. The collected specimens included fertilized eggs, trochophores, veligers, and settlement stage larvae. The activity of each studied enzyme showed strongly positive pairwise correlations with the activity of every other enzyme studied (r = 0.498–0.847, n = 60, p < 0.01). Pepsin showed the highest specific activity during the development of the veligers (p < 0.05). Pepsin and chymotrypsin specific activity followed broadly similar trends, except in late trochophore and early veliger stages. Trypsin specific activity was highest in early-stage veligers. Amylase specific activity progressively increased in middle-stage veligers, and decreased in older veligers. Cellulase activity started to increase before hatching, exhibiting its highest activity during the first seven days of veliger development. Lipase specific activity increased progressively in early-stage veligers and then decreased and remained constant until the end of observation. The in vitro digestibility assay showed that three mixed rations (75:25, 25:75, and 0:100 w/w) of Chaetoceros sp. and Isochrysis sp., and single components of Spirulina meal, and clam feed were suitable for early-stage veligers, while all mixed rations of Chaetoceros sp. and Tetraselmis sp., and single components of Spirulina meal and herbivorous fish feed were suitable for late-stage veligers. Our findings can be used as a feed management reference for spotted Babylon veligers

Optimal Replacement of Soybean Meal with Fermented Palm Kernel Meal as Protein Source in a Fish Meal-Soybean Meal-Based Diet of Sex Reversed Red Tilapia (Oreochromis niloticus × O. mossambicus)

The solid-state fermentation by effective microorganisms (containing photosynthetic bacteria, lactic acid bacteria, nitrogen-fixing bacteria, yeast and Bacillus sp.) improved the nutritive values of palm kernel meal (PKM). Increased crude protein (20.79%), nitrogen-free extract (40.07%) and gross energy (19.58%) were observed in fermented PKM (FPKM) relative to raw PKM while crude lipid (15.65%), crude fiber (36.45%) and ash (29.54%) were decreased. Replacement of soybean meal (SBM) with FPKM as a protein source was investigated for its effects in sex-reversed red tilapia (Oreochromis niloticus × O. mossambicus). The two-month-old fish (14.85 ± 0.28 g initial weight) were fed fish meal-SBM-based diets with replacement by FPKM at 25% (25FPKM), 50% (50FPKM), 75% (75FPKM) and 100% (100FPKM), while an FPKM-free diet (0FPKM) was used as a control. The five treatments, comprising triplicate cement ponds and forty fish each, were conducted in a recirculating system over 12 weeks. At the end of the feeding trial, fish fed the 50FPKM diet were superior in growth performance, while the feed utilization parameters were similar across all five treatments. Physiological adaptation of the protein-digesting (pepsin and trypsin) and lipid-digesting (lipase) enzymes was detected at all protein replacement levels (except for 25FPKM), as well as of the enzyme for cellulose digestion (cellulase), but not of the carbohydrate-digesting enzymes (amylase). Protein synthesis capacity in flesh was improved in fish fed the 50FPKM diet, while the quality of the main flesh proteins, actin and myosin, showed no significant differences across the five treatments. No differences in carcass composition and no negative effects on hematological parameters or liver histoarchitecture at the 50% replacement level of SBM by FPKM also support this alternative. Findings from the current study indicate the low-cost FPKM-containing diet for tilapia in comparison with control diet

Water depth and feed pellet type effects on growth and feed utilization in the rearing of green turtle (

The rearing of green turtles (Chelonia mydas Linnaeus, 1758) before their release to natural habitats has been practiced in several countries, whereas little information is available for inferring optimal husbandry protocols. This study aimed to improve the growth performance and feed utilization of post-hatching green turtles by varying the water depth (15 or 30 cm) and feed pellet type (sinking or floating pellets). The 20-day-old turtles (23.49 ± 0.02 g initial body weight) were subjected to a 2 × 2 factorial experiment (3 replications with 5 animals per tank) over a two-month duration. Growth, feed utilization, fecal digestive enzymes and hematological parameters were recorded to evaluate the effects of different treatments. No mortality was observed in any treatment group. Turtles reared in 15 cm water depth and fed with floating pellets exhibited superior growth (specific growth rate 2.76% body weight day−1) and feed utilization (feeding rate 1.42% body weight day−1, feed conversion ratio 0.61 g feed g gain−1, protein efficiency ratio 3.76 g gain g protein−1), relative to the other treatments. This treatment improved the utilization of nutrients by modulating trypsin specific activity but had no negative effects on hematological characteristics. Overall these findings indicate that the rearing program of post-hatching green turtles should be run with about 15 cm water depth and the preferred type of feed is floating pellets. These preferred conditions can also be applied in public displays, such as zoos or aquaria