Open-design Recirculating Systems for Zebrafish Culture

The zebrafish is an established vertebrate-animal model in biomedical research. Currently, their mass culture is mainly done using systems provided by commercial suppliers. Commercial systems are compact, recirculating, and use auto-cleaning tanks. These features minimize space use, labour cost, and water wastage; thus, facilitating maintenance of a large number of zebrafish using minimal resources. However, the often considered costs associated with these systems often impose a barrier to current and prospective researchers, especially those with limited funds or working in labs with no access to institutional centralized zebrafish culture facilities. In contrast to commercial systems, custom-made zebrafish maintenance systems are also described in the literature. To distinguish custom-made system from commercial systems, we termed them as “open-design” systems. Open-design systems are cost-effective, modular, and frequently being improved by zebrafish researchers. However, for further development and to present them as a viable option for zebrafish researchers around the world, a review of their current status and technical understanding is required. Here, we compile the disparate data on the purpose and technological development of the open-design systems. We believe this review will be a valuable resource for all zebrafish users and help streamline the open-design technology for zebrafish culture.     

Experimental investigation on the transport of different fish species in a jet fish pump

A jet fish pump with a throat of ø60 mm was designed to study its performance in the transport of different fish species and the physiological changes in fish thereafter. Experiments were conducted to investigate the fish transport rate and energy required to transport each ton of fish when transporting Carassius auratus, commonly known as the Chinese goldfish, Megalobrama amblycephala, or Wuchang bream, and Ctenopharyngodon idella, the grass carp. Fish were examined for external injuries as well as for several important enzymes and hormones which are indicators of tissue injury and stress. The results showed that the transport rate for all three species of fish rose dramatically with an increase in the primary stream rate. In this experiment, the transport rates of C. auratus, M. amblycephala and C. idella reached 2357 ± 37.2 kg ∙ h⁻¹, 2888 ± 41.6 kg ∙ h⁻¹, and 2060 ± 40.2 kg ∙ h⁻¹, respectively. However, both injury rate and energy required to transport each ton of fish increased no matter whether the primary stream rate was too low or too high. Considering both transport rate and injury rate, the mean primary stream rate of 80 m³ ∙ h⁻¹ was determined to be the optimal operating condition in this experiment. Fish were stressed and most likely some of their organs were damaged. However, most physiological indexes almost fully recovered after several hours.     

高蛋白料精等量替代鱼粉饲喂肥育猪对比试验

应用高蛋白料精等量替代鱼粉饲喂肥育猪 ,其结果在 42d试验期内高蛋白料精组头均增重 19.0 6kg ,比鱼粉组多增重 2 .12kg ,增重率提高 12 .5 2 %,头均多增收益 2 1.2 1元 ,差异显著 (P <0 .0 5 )。     

A computer vision system for oocyte counting using images captured by smartphone

This work proposes a computer vision procedure for counting Twospot astyanax (Astyanax bimaculatus) oocytes in Petri dishes using images captured by smartphone. First, the proposed procedure uses simple linear iterative clustering (SLIC) to divide the images into groups of pixels (superpixels). Then, based on their color and space characteristics, the images are classified into light background, dark background, dirt, or oocyte by a machine learning algorithm. Five different types of machine learning algorithms were tested: support vector machines (SVM), decision trees using the algorithm J48 and random forest, k-nearest neighbors (k-NN), and Naive Bayes. To train the algorithms, 8.578 superpixels were classified by an expert into oocyte (n = 354), dirtiness (n = 651), dark background (n = 3.622), and light background (n = 3.951). Of the five learning algorithms, SVM obtained the best result with 97% correct oocyte recognition. Given the wide availability of smartphones, we therefore conclude that the presented procedure can be a valuable tool in future experiments and studies on fertilization and hatching success in Twospot astyanax.     

Monitoring shrimp growth with control charts in aquaculture

This work proposes a method for the statistical monitoring of the weekly weight of shrimp in a fish farm. The design of control charts for shrimp growth presents several challenges, the main ones being the presence of trend and autocorrelation. Several control charts are proposed, the most efficient being a chart based on the residuals of a second order autoregression whose parameters vary with the week. A control chart with less computational complexity is also provided. It is simply based on growth rates and works well at detecting negative weight changes. Real data from a large shrimp farm has been used for both the design and the evaluation.     

Effect of menhaden fish oil supplementation and lipopolysaccharide exposure on nursery pigs. II. Effects on the immune axis when fed simple or complex diets containing no spray-dried plasma

A trial using 64 weanling pigs (TR4×PIC C22) was conducted to determine the effects of menhaden fish oil supplementation and diet complexity on performance and immune response of nursery pigs. Pigs (17 days and 6.27±1.16 kg) were weaned into a segregated early wean facility and given free access to a complex diet for 7 days post-weaning. At day 0 (day 7 post-weaning), pigs were blocked by weight and allotted to 64 pens. Treatments (Trt) were arranged as a 2×2×2 factorial arrangement. Main effects included diet (complex versus simple), oil (menhaden fish (MFO) versus corn (CO)), and immunogen (saline versus lipopolysaccharide (LPS)). Experimental diets contained 6% oil (6% CO or 5% MFO+1% CO) and were fed for 14 days. On day 12, i.v. injections of either LPS (150 μg/kg) or saline were given, followed by blood collection at 30 min intervals for 6 h. After the immune challenge (day 14), pigs were placed onto a common corn-soybean meal fortified diet and growth performance was evaluated until termination of the study (day 28). Pigs were weighed and feed intakes recorded at 7, 14, and 28 days. Prior to immune challenge (day 12), there were differences in BW for pigs fed complex versus simple diets (P<0.01; 13.1 and 12.1 kg, respectively) and pigs fed CO versus MFO diets (P<0.05; 12.9 and 12.3 kg, respectively). During the challenge period, for pigs treated with LPS there was a Time×Immunogen×Oil effect (P<0.001) for serum cortisol with MFO fed pigs having lower serum cortisol as compared to CO fed pigs. Also, during the challenge period, for pigs treated with LPS there was a Time×Diet×Immunogen×Oil effect (P<0.001) for serum tumor necrosis factor- (TNF-) with pigs fed complex diets supplemented with CO having higher serum TNF- as compared with pigs fed complex diets supplemented with MFO. At days 14 and 28, LPS-treated pigs had lower BW than saline injected controls (P<0.001 and 0.01, respectively). In addition, pigs fed simplified diets continued to have lower BW after challenge compared to pigs fed a complex diet. Interestingly, there were no differences (P>0.10) in BW after challenge in pigs fed MFO. This study suggests that MFO supplementation alters the immune response during LPS challenge and that simplified diets may compromise nursery performance.     

Tissue-specific antioxidative and neurotoxic responses to diazinon in Oreochromis niloticus

The purpose of this study was to evaluate oxidative stress and neurotoxic potential of organophosphorus (OP) insecticide diazinon in the sentinel freshwater fish, Oreochromis niloticus. Antioxidant and acetylcholinesterase (AChE) enzyme activities and malondialdehyde (MDA) and protein levels were measured spectrophotometrically in gill, kidney, alimentary tract, and muscle tissues of fish treated with sub-lethal diazinon concentrations for 1, 7, 15, and 30 days. Dose-dependent inhibitions of AChE were observed in all the experimental fish. On the contrary of alimentary tract, MDA levels were elevated in kidney and muscle and gill was not affected. AChE and MDA levels intercorrelated in kidney and muscle tissues. Diazinon had increased superoxide dismutase (SOD) activities in all the tissues, while kidney was the most affected tissue. Tissue-specific alterations were observed on catalase (CAT) and glutathione peroxidase (GPx) activities; however, the activities were not changed in gill and muscle tissues for GPx and in gill, muscle, and kidney tissues for CAT. Protein levels decreased in kidney, muscle, and alimentary tract, while increased in gill and alimentary tract in 15 days. With respect to these results, diazinon has oxidative and neurotoxic potentials in O. niloticus. Observed changes with diazinon treatment were generally tissue-specific and dose-dependent.