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Utilization of live feeds in fish larviculture: A review
103-116Views:18This review examines the significance of live feeds in commercial aquaculture industry for production of fish and shrimp larvae, along with various challenges and prospects. Live feeds are an essential food source in larviculture, especially for marine fish, which depend on them for nutrition during the initial days of exogenous feeding. They are palatable, highly digestible, and their movement stimulates natural hunting and foraging instincts, promoting better development, lowering captivity stress, and increasing survival rates. Artemia is the most commonly used live feed in larviculture; however, it has low levels of omega-3 HUFA. Copepods are the most nutritionally rich live feed, containing high levels of DHA and EPA. Despite these benefits, they are less frequently used in larviculture due to technical challenges associated with large-scale cultivation at high densities. The use of live feed is labour-intensive and costly. The feeding period for fish larvae can be shortened using a co-feeding strategy. Microalgae rich in DHA have been utilized to enrich live feeds. Further research is needed to determine the most effective approach to significantly reduce the weaning time of fish larvae from live feed. This will lead to gradual and eventual complete replacement of life feed in the near future.
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Effect of different weaning time on the growth and survival ofCommon carp (Cyprinus carpio L.) larvae
55-59Views:736Within our experiment, we studied the combined effect of live food application and feed training on the production parameters of carp larvae. In addition, we examined whether there is a difference in the growth rate and survival rate of the specimens of Szeged mirror landrace reared in similar stocking density but with different treatments.
Specimens of Szeged mirror landrace from induced propagation were placed into 12 pieces of 40-liter aquaria. For the 4 different treatments, (K, A3, A6, A9), live food (Artemia salina) was fed, as well as feed training was applied.
We also sought to find an answer as to how our feeding and rearing conditions can affect the production parameters of common carp fries and what impact these conditions may have on their survival rates. At the end of the 2-week experiment we determined the individual weight gain of the carp fries, their survival rate and the biomass growth. The purpose of the study is to examine the optimum timing of shifting from live food to feed for carp larvae.
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Preliminary results on Siberian sterlet (Acipenser ruthenus marsiglii) fries rearing under intensive conditions
27-31Views:212In our experiments production performances of Siberian sterlet were tested under intensive tank conditions. During the 25 days long experiment effectiveness of weaning to artificial diet of the fish was investigated. Production performances of fish fed on exclusively dry diet from the beginnings were lower than the other two groups. Between the values of sterlets fed on live food also then suddenly vs. continuously were weaned to dry diet there were no significant differences. Based on our results live food feeding could be suggested for the Siberian sterlet larvae for some days but the method of the weaning to dry diet has no significant influence to the production performances.
In 21 days long experiment four different feeding frequencies were tested in Siberian sterlet (~13 g) fingerlings. Dry feed was offered for the fish continuously, 2, 3 and 4 times per day. There were no significant differences between the values of the four treatments. Based on our results there is no high influence of feeding frequency in case of this size group of Siberian sterlet.
During the nursing in two different size groups of Siberian sterlet the optimal daily amounts of feed were aimed to determine. In case of growth values of the group fed at 7% of the total biomass were higher than the other two groups (3 and 5%). Feeding performances of fish fed at 5% were significantly better than fish fed at 7%. Based on our results for ~20 g size of the subspecies at least 5% of total body weight could be suggested.
In case of ~150 g size of the fish the production performances of fish fed at 1% were lower than the other two groups (2 and 3%). Between the values of stocks fed at 2 and 3% there were no significant differences. Based on these results 2% of total body weight of dry feed could be suggested for the Siberian sterlet with ~150 g body weight.
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A review on fish in vitro digestion studies
55-63Views:4(1) Background: In vitro experiments in fish have been developed to search for dietary substitutes of fish meal in aquafeeds by measuring the digestibility of various feedstuffs by simply simulating the conditions of the stomach or portions of the digestive tract. In vitro digestion studies involving mainly commercial fish species have been conducted to determine the digestibility of conventional and alternative ingredients in fish diets using diverse digestion models. However, there remains a significant knowledge gap, particularly regarding the enzyme functionality, digestion mechanisms in many fish species, and the factors influencing enzymatic activity. This review article is focused on the importance of the use of different enzyme sources in the in vitro digestion model to predict protein hydrolysis.;(2) Methods: For this review, a comprehensive analysis of articles was conducted to gain insights into diverse enzyme interactions and feed evaluation assessments, from the nutritional science and biotechnology sector.; (3) Results: A total of 36 peer-review papers, which include original, and review articles were selected.; (4) Conclusions: In vitro digestion studies offer a valuable tool for evaluating the digestibility of conventional and alternative feed ingredients, helping to identify sustainable dietary substitutes for fish meal while reducing dependence on live animal trials.
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Awareness and adoption of a nurse sow management system among small-scale pig farmers in Nakuru County, Kenya
113-120Views:327This study aimed to assess the level of awareness and adoption of nurse sow management strategies among small-scale pig farmers in Nakuru County, Kenya. The research included a survey of pig farmers who visited the Nakuru Agricultural Show in July 2023. A total of 139 farmers were interviewed within 5 days of the show. The corresponding author interviewed the respondents in a face-to-face engagement, where questions on nurse sow management were initially drafted in English and translated into Kiswahili, i.e. the second language in Kenya. The obtained results indicated that farmers came from two main regions of the county: the northern part (54.7%, 76/139) and the southern part (45.3%, 63/139). Levels of awareness and adoption were insignificant between the two groups (χ2, p<0.05). A major obstacle to the adoption of this strategy was identified as feed challenge at 77.7%; (108/139) and market issue at 59.7%; (83/139). This study identified important aspects and limitations that should be considered when developing sustainable productivity development strategies for Kenyan pig farmers. To assist the sustainable growth of small-scale pig production, the authors suggest government measures that shield farmers against exploitation of feed and marketing components, as well as advocating for effective breeding to increase live born.
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Use of essential trace elements enriched Artemia in the larval rearing of barramundi (Lates calcarifer)
11-16Views:343Artemia is a vital nutriment in the rearing of barramundi (Lates carcarifer), however it’s mineral trace element content does not cover the requirements of the larvae. In our experiment the assumption was wether the cobalt, zinc and manganese concentration of Artemia could be increased during a 24 hours of enrichment period, as well as we wanted to investigate the resulted interactions between the elements. For this purpose 50, 100 and 1000 mg l-1 cobalt-chloride treatements (Co50, Co100, Co1000) were applied while in the case of 50 and 100 mg l-1 treatments the enrichment was also complemented with zink-sulphate and manganese-chloride in the same concentrations. According to the results the zooplankton were able to accumulate cobalt in higher amount, and yet zinc and manganese had no significant effect on each other, a strong synergistic effect occurred between cobalt and manganese. After the enrichment period the impact of essential trace element supplemented live feed on the survival and growth of barramundi larvae was also studied. The experiment was carried out by using 15 days-old larvae applying a total of 9 treatments for two weeks (Control, Co50, Co100, Mn50, Mn100, CoZn50, CoZn100, CoMn50, CoMn100), in duplicates. Considering the per cent of survivals, no significant difference was observed between the treatements (P>0.05). In the case of CoMn50 and CoMn100, the loss statistically increased (P<0.05) compared to the Control (80.5±4.95%) group. Our results show, that the Mn100 and CoMn100 treatements resulted in ignificantly higher (P<0.05 ) in divid ual bod y w eight s, how ever taki ng the survival also into consideration the Mn100 treatements proved to be the most
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The effect of feeding different glycerol sources on the performance of lactating sows
99-103Views:248Glycerol is a by-product of the biodiesel industry and it might be a good alternative to moderate the energy deficiency of sows during the lactation period. Preliminary experiments were carried out to test the effect of a powder, solid based “food grade” glycerol source with 72.9% glycerol content (Trial 1) and a liquid “feed grade” glycerol source with 86% glycerol content (Trial 2) on the performance of lactating sows and their litters. Trial 1 was conducted with 5 Hungarian Large White×Hungarian Landrace sows/treatment (313±24.9 kg) and Trial 2 with 12–12 DanAvl (323±17.0 kg) sows and their litters/treatment. Neither the solid, powder based glycerol (Trial 1), nor the liquid glycerol source (Trial 2) had significant effect on the feed intake, reduction in live weight and back-fat thickness, and weaning-tooestrus interval (p>0.05) of lactating sows. In Trial 2, on the 14th, 21st and 27th days of lactation the milk samples were collected and it was found that 50 kg/t glycerol decreased the protein content of milk samples (p<0.05). Glycerol supplementation had no effect on dry matter, fat, lactose content of milk samples (p>0.05). In Trial 2, no significant difference was found between control and experimental sow groups in triglyceride concentration of blood samples and in the activity of liver enzymes (ALT, AST, GGT; p>0.05), but the concentration of plasma glucose and cholesterol increased tendentiously (p<0.10).
Based on our preliminary results, it can be concluded that additional dose trials are needed to perform in order to study the effect of glycerol supplement on milk production and on metabolic processes of lactating sows.
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New Possibilities of Brown Bullhead (Ictalurus nebulosus) Farming
55-57Views:163The brown bullhead (Ictalurus nebulosus) has been settled in Europe at the end of Century XIX from North America. In Hungary it has been brought in 1902. The naturalization of this species was successful because the brown bullhead found adequate conditions for its life and reproduction in Hungary. But it was unsuccessful because lost its excellent growth.
In inland water habitats-and that’s why also fishponds-extraordinarily multiplied, but because of its slight growth this species is undesirable for the native farmers. The brown bullhead is concurrent for domestic fish species, on the other hand its weight not more than 150-200 g. Occasionally it was exterminated, but multiplied again and again.
In 1999 we placed out black bullhead offspring in a pool of a new intensive fish farm, in order to breed at least 300-350 g weight for the customers. The accidental trial was surprisingly successful. Consequently, the black bullhead prefers the artificial food, and produces excellent growth parameters and specific feed-live weight conversation ratio.
On the 20th of September 1999 there was placed 23 300 pieces of brown bullhead offspring, with 28 g average weight and 625 kg gross weight. When we sold them on the 22nd of February 2000, the gross weight was 3387 and the live weight gain was 2735 kg. The gross weight of the feed was 3041,8 kg, and the feed-live weight conversation ratio was 1,11 kg/kg.
Because of this successful trial the managers of the farm wanted to start systematic experiments to work out the details of the intensive farming of brown bullhead. We undertook to help to find the right place of the species in the Hungarian fish processing because of the increasing native and foreign demand.