Ontogenic development of digestive enzymes in bigfin reef squid (Sepioteuthis lessoniana)

Bigfin reef squid (Sepioteuthis lessoniana) is an economically important exported aquatic animal in Thailand, but little is known about its husbandry, which needs to be clarified. In this study, the ontogenic development of the main digestive enzymes (pepsin, trypsin, chymotrypsin, lipase and amylase) was investigated within 30 days after hatching (DAH). Fertilized eggs of the wild cuttlefish were hatched and then distributed into four replicate aquaria assigned to varying collection times (0, 5, 10, 15, 20, 25 and 30 DAH). The development of pepsin suggests acidic digestion functionality at 5 DAH, and its specific activity was maintained over the studied period. Specific activities of the serine proteases, trypsin and chymotrypsin, fluctuated significantly with similar pattern, and appear to be the key enzymes contributing ontogenic changes in protein catabolism. The specific activity of lipase was relatively high at 0 DAH, dramatically increased by 5 DAH, and then appeared constant until the end of observations, suggesting important role in utilizing the lipid from yolk at hatching, as well as probably in sparing protein utilization. Dramatic increase in amylase specific activity occurred by 10 DAH after which the activity was constant until 30 DAH, suggesting the utilization of carbohydrate as energy evolves comparatively late. Findings from the current study could be used to manage nutritional protocols according to the digestive enzyme patterns, as well as to develop artificial diets for rearing S. lessoniana.     

Pre‐soaking of the feed pellets: a trick for successful feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758)

Pre‐soaking of the feed pellets in water can improve feed utilization in juvenile green turtles (Chelonia mydas Linnaeus, 1758), but the pre‐soaking has not previously been optimized. This study aimed to optimize the water amount used for pre‐soaking the pellets. The experiments followed a completely randomized design with three replications of each dietary treatment group. Initially 10‐day‐old green turtles (20–22 g body weight) were treated in an indoor aquaculture system for 3 months. The dietary treatment pellets were pre‐soaked with 0.3, 0.5 or 0.7 (v/w) relative amounts of water that are here termed soaking ratios. At the end of experiment, there were no significant differences in survival (96% on average) and growth (average body weight 75.34 g and specific growth rate 2%/day, on average) of turtles in three dietary treatments (p > 0.05). Feed utilization was the best in turtles fed with 0.7 pre‐soaked ratio, as indicated by significant reductions (p < 0.05) in the feeding rate (7.44% body weight/day) and the feed conversion ratio (1.12 g feed/g gain). Digestion was also improved by the induction of faecal digestive enzymes as well as the faecal thermal properties. The rapid growth did not negatively affect the general haematological parameters of reared turtles. These findings indicate that the pre‐soaking of feed pellets at the optimal soaking ratio (1:0.7 w/v of pellet to water) can contribute through improved feed utilization of green turtles.     

槟榔叶片和花序的体细胞胚胎发生及植株再生

本研究以不同槟榔品种的幼嫩叶片及花序为外植体成功实现体细胞胚胎发生及植株再生.试验结果显示,不同品种及外植体均以毒莠定为最佳愈伤组织诱导剂.诱导所获愈伤组织需连续用生长素浓度由高到低的一系列培养基进行继代培养才能不断生长并诱导体细胞胚胎.当愈伤组织最终转移入无激素MS配养基后可观察到体细胞胚胎发生.胚胎萌发以附加20 ...     

Pigment deposition and in vitro screening of natural pigment sources for enhancing pigmentation in male Siamese fighting fish (Betta splendens Regan, 1910)

Distribution in pigment deposition was studied in male Siamese fighting fish (Betta splendens Regan, 1910) of solid Blue and solid Red phenotypes. Growths were similar, and also indicated by similar activity ratio of trypsin to chymotrypsin. Growth strategy was different at maturing stage, whereas trypsin expression decreased in solid Blue while chymotrypsin expression decreased in solid Red (P ≤ 0.05). Ranking of total pigment contents was muscle > skin > caudal fin > anal fin > dorsal fin > pelvic fin > pectoral fin. Immature fish had similar total contents and concentrations of pigments, except solid Blue had higher total contents in dorsal fin than solid Red. At maturing stage, solid Blue showed higher total pigment contents than solid Red due to higher contents in the fins. Solid blue had higher concentration in pelvic fin, while solid Red had higher in pectoral and dorsal fins. Age, phenotype and their interaction influenced pigment deposition. Determinations of pigment levels, high temperature tolerant of pigments and in vitro digestibilities of pigments, protein and carbohydrate from twenty natural sources indicated that fermented red rice was the most suitable pigment source, following with Chlorococcum sp.     

Screening of in vitro nutrient digestibility coefficients of selected insect meals in broiler chickens,black-meat chickens and quails

The objective of this study is to identify potential insect species comparing with commonly used protein sources based on efficiency of the in vitro digestibility on dry matter (DMd), organic matter (OMd) and crude protein (CPd) in broiler chickens, black-meat chickens (Native breed) and quails. Each of gastric mucosa, pancreas and duodenal mucosa were obtained from proventriculus, pancreas and duodenum, respectively. Crude digestive enzyme extracts (CTE) were extracted from these organs to perform in vitro digestibility. Eighteen insect samples and six commonly used protein sources were served as substrates which were evaluated on DMd, OMd and CPd in triplicate for each substrate. The CTE from gastric mucosa was used to simulate proventriculus, whereas small intestine was simulation by adding the CTE from pancreas and duodenum. The large variation of chemical composition between insect meals was presented. For commonly used protein sources, animal proteins were higher on digestibility than plant proteins (p < .001). Quails represented a great potential to digest insect meals comparing other animals. Based on CPd results, there were potential insect species for broiler chickens (Achroia grisella: AG, Tenebrio molitor: TM and Musca domestica), black-meat chickens (Patanga succincta, TM and AG) and quails (Hermetia illucens, Acheta domesticus and Locusta migratoria; p < .001). The evidences from this study suggest that these insect species contain a great potential to use as alternative protein sources promoting an animal production with sustainability. However, the in vivo experimentation must be performed to confirm in further study.     

Minimal water volume for intensively producing male Siamese fighting fish (<Emphasis Type="Italic">Betta splendens</Emphasis> Regan, 1910)

Water volume is a key parameter affecting the individual rearing of male Siamese fighting fish (Betta splendens Regan, 1910). In this study, minimization of water volume was pursued by assessing growth, feed utilization, digestive enzyme activities, color coordinates, muscle quality, and carcass composition. One-month-old solid-red male fish (0.97?±?0.01 g initial body weight) were distributed individually into glass aquaria with five alternative water volumes (100, 150, 200, 250, and 300 mL), comprising 15 fish per treatment (n?=?15), over 8 weeks duration. No mortality of the reared fish was found during the study. Growth performance and feed utilization of the fish reared in 150 mL water were superior to the other treatments. The water volume significantly affected specific activities of the digestive enzymes (P ? 0.05), except for amylase, and no differences in enzyme activities were observed between fish reared in 150 and in 300 mL water. The preferred treatment maintained skin lightness (L*) and had the highest redness (a* and a*/b*) among the treatments. Protein synthesis (RNA concentration) and its turnover rate (RNA/protein ratio) and myosin and actin in muscle also benefited from this treatment. Carcass composition, in terms of moisture, crude protein, and crude ash, was maintained, but the amount of crude lipid fluctuated with water volume. Based on our experiments, the preferred minimal water volume for individual rearing of male Siamese fighting fish should be about 150 mL.     

Fish condensate as effective replacer of fish meal protein in diet for striped snakehead, <Emphasis Type="Italic">Channa striata</Emphasis> (Bloch)

The optimal protein replacement of fish meal (FM) by fish condensate (FC) was investigated in striped snakehead, Channa striata (Bloch) (1.78 ± 0.02 g initial weight). The FM-based diet (0FC) was replaced by substituting protein from FC for 100 (100FC), 200 (200FC), 300 (300FC), 400 (400FC), 500 (500FC) or 600 (600FC) g kg^?1 of the FM, and a commercial diet (CD) for carnivorous fish was included for comparison. The experiment was conducted indoors under completely randomized design (8 treatments × 3 replications × 60 fish per pond) over a 6-month trial. There were no significant differences in water quality during the experiment. The fish fed with 500FC had superior growth performance and feed utilization. This dietary treatment gave similar levels to all observed specific activities of digestive enzymes as did baseline 0FC. Survival, carcass composition, hematological parameters and liver histopathology were not negatively impacted by this protein replacement level. Economic analysis also supports the use of this by-product as a potent protein replacer in striped snakehead diet. Findings from the current study indicate that a 500 g kg^?1 protein replacement of FM by FC is near optimal for striped snakehead, and similar use of it in the aquafeed of other species appears worth further studies.     

Optimal background colour for rearing Asian seabass (Lates calcarifer)

Background colour influences the growth performance and feed utilization of various fish species. In the current study, the effects of different aquarium backgrounds (transparent, white, black, red, green and blue) on growth performance, feed utilization, digestive enzyme activities, flesh quality, carcass composition and haematological parameters were investigated in Asian seabass (Lates calcarifer). The fish (16.17 ± 0.02 g initial body weight) were distributed into eighteen glass aquaria (6 treatments × 3 replications) with the various background colours and reared for 10 weeks. At the end of the experiment, positive growth performance and feed utilization were observed in fish reared against transparent, white, black or green backgrounds, while negative effects were noted for fish reared on the remaining treatments (p < .05). Modulation of the main digestive enzymes was observed across the six treatments, indicating different strategies for utilizing nutrients by the fish. The activity ratio of trypsin to chymotrypsin was highest in the fish reared against a black background, followed by a white background. Flesh quality, in terms of protein synthesis capacity and protein turnover rate, indicated a significant improvement in the fish reared against white, black and green backgrounds, while the contents of myosin and actin were similar across the six colour treatments. Carcass composition and haematological parameters showed no negative effects in either of the preferred treatments. These findings indicate that the most suitable background colours for rearing Asian seabass are black, followed by white and green, while transparent, red or blue backgrounds are unsuitable.