Sustainability of agriculture extension services in the face of COVID-19: a study on gender-specific market systems

In the fourth industrial revolution, achieving sustainable agricultural development while feeding a growing world population and maintaining a balanced interrelationship between the economy, society, and the environment has been a significant challenge. However, COVID-19 disrupted agricultural extension and advisory systems, affecting all market participants. The complexity of the pandemic has impacted the private sector, public sector, extension staff, donor funding, education, and research systems, subsequently affecting human nutrition. This paper aims to expertly review COVID-19’s effects on the sustainability of gender-specific agricultural extension service systems. Demand and supply market stakeholders in the extension system are thematically discussed. The findings reveal various consequences of COVID-19 for market actors on both the demand and supply sides of the extension system. Private-sector players often support expansion directly or indirectly, with multi-sectorial support and funding strategies existing for sustainability. In many developing nations, the comprehensive extension system was disrupted by COVID-19, impacting household incomes and nutrition. The pandemic accelerated the adoption of digital technologies in many developing nations, transitioning from a centralized to a decentralized and pluralistic extension model. Multi-sector coordination and execution, especially from health and other sectors, are crucial in managing complex crises that disrupt the market system

Repellent effects of some plant oils on Dermestes maculatus larvae in Smoke-dried West African lungfish (Protopterus annectens)

AbstractDermestes maculatus accounts for about 71.5% of dried fish infestation in most of the producing areas with a substantial loss in both dry weight and nutritional value. The study aimed to evaluate the repellent effect of oils extracted from Garlic (Allium sativum), Coconut (Cocos nucifera), Ginger (Zingiber officinale), Jatropha (Jatropha curcas), and Neema (Azadirachta indica) on Dermestes maculatus larvae in smoke-dried Protopterus annectens. The extracted oils from each plant were applied to the fish at varying concentrations of 0.001, 0.004, 0.016, 0.064, and 0.256 ml/g fish in triplicates. Late instar larvae of D. maculatus were introduced into Kilner jars containing fish treated with these oils and repellency was monitored for 24 hrs. Repellency was highest (87%) in A. sativum oil and lowest (59%) in A. indica oil at the highest concentration (0.256 ml/g of fish) within 24 hrs. of exposure. Furthermore, an increasing trend in repellency was observed with increasing concentrations of oils from all the plants used. The order of repellency performance was A. sativum > C. nucifera > Z. officinale > J. curcas > A. indica, starting with the highest to the lowest. Therefore, this study demonstrates the repellent properties of the oils in offering effective protection against infestation and damage by D. maculatus, suggesting that the oils can be utilized in post-harvest preservation of smoke-dried fish

Embracing nanotechnology for selenium application in aquafeeds

Selenium (Se) is an important micronutrient that has been used in aquafeeds for the normal growth, welfare and health of aquatic animals. Through nanotechnology, Se can be converted into nanoparticles that are more bioavailable, utilized and absorbed by aquatic animals. However, this is still a new and emerging area of research in aquafeeds. This paper aims to review the effect of Se and Se nanoparticles (Se-NPs) application in aquafeeds on aquatic animals. Specifically, different compounds of Se, requirement levels by different species, effects on animal growth, physiology, antioxidant capacity and immune response have been highlighted. The review shows that the application of Se in aquafeeds could improve the growth performance, physiology, antioxidant enzymes, immunity and disease resistance in aquatic animals. However, the effectiveness could be highly influenced by the source of Se, aquaculture species and administration quantity. Through nanotechnology, the utilization and absorption of Se could be improved while reducing its toxicity. Therefore, Se-NPs present an efficient way to utilize nutrients in aquafeeds. Important gaps, however, exist in the current knowledge, particularly with regard to the response of shrimps and crustaceans to dietary supplementation of Se and Se-NPs as most of the existing studies have focused on fish species. Also, some species of economic importance and life stages have not been investigated, which hinders the embracement of nanotechnology in aquafeeds production

Dietary tea polyphenol supplementation and its impacts on growth performance, plasma parameters, and antioxidant capacity of juvenile genetically improved farmed tilapia (GIFT: Oreochromis niloticus)

The term ‘tea polyphenols’ (TPs) comprises a broad range of polyphenol compounds present in tea, demonstrating positive health effects such as antioxidant activity, etc. in animals. This study investigated the effects of TPs supplementation in juvenile genetically improved farmed tilapia (GIFT); Oreochromis niloticus). Fifteen fish (weight: 13.46 ± 1.25 g) were distributed in six tanks and randomly assigned with diets containing graded levels of TPs (mg/kg): 0.00 (control), 100, 200, 300, 400 and 500 in quadruplicate for 8 weeks. After the trial, the fish fed 500 mg/kg TPs exhibited a significant reduction (p < 0.05) in final body weight (FBW) compared with the control. Whole-body moisture content was elevated, while crude protein was lowered significantly (p < 0.05) by a 100 mg/kg TPs diet compared with the control. Plasma low-density lipoprotein (LDL) was significantly elevated (p < 0.05) at over 200 mg/kg; triglyceride (TG) content was lowered (p < 0.05) by the TPs diet compared with the control diet. Catalase (CAT) was significantly enhanced (p < 0.05) by TPs except at 300 mg/kg; superoxide dismutase (SOD) was increased (p < 0.05) by 200, 400 and 500 mg/kg; total antioxidant capacity (T-AOC) was enhanced (p < 0.05) by 400–500 mg/kg; glutathione (GSH) was improved (p < 0.05) by 500 mg/kg; and malondialdehyde (MDA) level was elevated (p < 0.05) in the 100–200 mg/kg TPs diet compared with the control. TPs can be utilized as a feed supplement to improve the plasma biochemical parameters and AOC of GIFT juveniles

Nutritional requirements and effect of culture conditions on the performance of the African catfish (Clarias gariepinus): a review

AbstractAquaculture is crucial for global food and nutrition security due to the inability of wild harvests to meet increasing demand. Africa’s contribution to aquaculture is generally low, despite its potential for economic development, food security, and reduced unemployment. The study focuses on the African catfish (Clarias gariepinus) a freshwater fish species that is widely farmed for food in Africa and other parts of the world. Proper nutrition is essential for the growth and development of the fish, and understanding their nutritional requirements is critical for producing healthy and high-quality fish. This review article provides an overview of the knowledge on the nutritional requirement of the African catfish, including protein, lipids, carbohydrates, vitamins, minerals, and amino acids. The recommended protein content for juvenile fish is between 40 and 50% and for adult fish is between 30 and 40%. Based on the reviewed studies, the recommended amount of methionine in C. gariepinus diets ranges from 18.7 to 29.7 g/kg of protein while the lysine requirement ranges from 44.9 to 62.2 g/kg protein). The recommended lipid content in the diet is between 5–15% for juvenile fish and 5–10% for adult fish. The African catfish requires a low-carbohydrate diet, with recommended carbohydrate content between 26 and 32%. They require a variety of vitamins, including vitamin A, vitamin D, vitamin E, and vitamin C, as well as minerals, such as calcium, phosphorus, and potassium. Clarias gariepinus also require a variety of essential and non-essential amino acids. Besides the nutritional requirements, culture conditions also have a significant effect on the feed performance. The recommended conditions include temperature ranging from 28 to 32 °C, Light intensity of 150 Lx, 12D:12L photoperiod, and stocking density in earthen of 7 fish m−3. Overall, understanding the nutritional requirements of C. gariepinus is crucial for the successful fish farming and sustainable aquaculture. Information in this review will be built to further guide the development of feeds for C. gariepinus

Application of anaesthetics in fish hatcheries to promote broodstock and fish seed welfare in Zambia

AbstractThis study investigated the application of anaesthetics in 23 private and government-owned hatcheries in 10 provinces of Zambia. The study employed both qualitative and quantitative research designs and used a structured questionnaire to collect data from the respondents. The results showed that most hatcheries (65%) were not using anaesthetics in handling fish and all (100%) that were using anaesthetics (35%) used clove powder as the only type. Most respondents (61%) were not sure or did not have information about the availability of the anaesthetic substances in their localities while only 26% reported wider availability but 13% had a divergent claim. The mortality rate for fingerlings in hatcheries that applied anaesthetics ranged between 15–30% with consistently high demand while those that did not use anaesthetics reported mortality rates of more than 50% and had low demand. The majority of the respondents (53%) had received training up to certificate level, followed by those who had attained up to a diploma qualification (27%) while those that attained up to a degree (13%) and general skills (7%) levels were in the minority. Furthermore, most respondents (35%) did not know the importance of fish anaesthetics. We conclude that the use of fish anaesthetics in Zambian hatcheries is very low and could partly be the cause of high fingerling mortalities, and there is an urgent need to address the situation

Morphometric, Histochemical, and Ultrastructural Analysis of the Reproductive System and Spermatogenic Stages of Male Blue Crab (Callinectessapidus Rathbun, 1896)

The blue crab, Callinectes sapidus Rathbun, 1896, is considered to be a luxury meal, especially in touristic cities. It contains more than 20 types of amino acids and provides all the needed amounts for human growth. This study describes the morphology and complex differentiation in the gonadosomatic index, morphological and ultrastructure features of the reproductive system, spermatogenesis, and spermatophores structure; this is due to the need to maintain natural and fishing stocks. Mature adult male crabs (carapace length 59 ± 7.12; width 126 ± 18.8 mm) were obtained from Abu-Qir Bay from November 2018 to October 2019 and transported alive in seawater to the laboratory. The reproductive system was dissected and weighed to the nearest 0.001g using the electronic balance, and the gonadosomatic index was subsequently calculated. The morphological analysis showed the developing testes with highly compacted seminiferous tubules. Using Periodic acid–Schiff stain, the spermatophore appeared with a zigzag-shaped wall that indicates its carbohydrate constituents. Each Spermatophore consisted of an inner spermatozoal mass embedded in a matrix, whose main components were secretions 1 and 2, and an outer thin acellular layer composed of secretions 3 and 4 from the anterior vas deferens (AVD). Secretions 5 and 6 (S5 and S6) also appeared with carbohydrate constituents using Mallory triple stain. The transverse section of the middle vas deferens (MVD) showed spermatophores with rod-shaped secretion S6 and granular secretions 7 (S7), forming a complex matrix between spermatophores. The secretion found in the MVD was granular, strongly acidophilic, and secreted by its highly columnar epithelium (S7). The ultrastructure showed that the testes were surrounded by a monolayer of myoid cells with an elongated nucleus, which also contained the following stages: spermatogonia, primary spermatocyte, secondary spermatocytes, and spermatids as well as spermatozoa. On the other hand, scanning electron microscope studies for fully formed spermatophore taken from the middle part of the vas deferens indicated that it is ellipsoidal in its outline with terminal stalk. Furthermore, the spermatophore was surrounded by a thick capsule of non-cellular substances and contained mature spermatozoa

Effect of fishmeal replacement with dried red wigglers (Eisenia fetida) worm meal on growth and feed utilization, production efficiency, and serum biochemistry in Nile tilapia (Oreochromis niloticus) fingerlings

This study investigated the effect of replacing fishmeal with red wigglers (Eisenia fetida) worm meal (RWWM) in the diet of Nile tilapia (Oreochromis niloticus) fingerlings. Red wigglers worms (RWW) were culture on a vegetable by-product medium, harvested and dried to obtain red wigglers worm meal. The fish (average weight ± SE: 7.70 ± 0.06 g) were fed with seven diets (30% crude protein and 7.5% crude lipid), in which fishmeal was replaced with 0%, 5%, 10%, 15%, 20%, 25%, and 30% RWWM. The fish was reared in 1000 L fiberglass tanks in a recirculating aquaculture system and were hand-fed twice daily for 90 days. At the end of the experiment, the growth, feed conversion ratio, and energy utilization improved when feeding 15% and 20% RWWM compared with the control diet (P < 0.05). Using broken line regression between growth efficiency and feed utilization, showed the optimum level of RWWM replacing FM in Nile tilapia fingerlings diet was around 21 – 22% of the diet. The whole-body crude protein and ash content were elevated in the fish fed with 10–25% RWWM, while crude lipid and energy contents were elevated in the fish fed with 5–25% RWWM compared with the control group (P < 0.05). The essential and non-essential amino acids profiles of the fish were improved by 15% and 20% RWWM compared with the control (P < 0.05). The plasma glucose was decreased by 15–20% and significantly enhanced in fish fed with 25–30% RWWM diets compared with the control (P < 0.05). The total protein, albumin and globulin increased in the fish fed 15–20% diets and decreased in fish fed the 30% RWWM (P < 0.05). Therefore, this study demonstrates that RWWM could replace 20% fishmeal in the diets of Nile tilapia fingerlings without negatively affecting fish growth and physiological performance

Sustainability of agriculture extension services in the face of COVID-19: A study on gender-specific market systems

In the fourth industrial revolution, achieving sustainable agricultural development while feeding a growing world population and maintaining a balanced interrelationship between the economy, society, and the environment has been a significant challenge. However, COVID-19 disrupted agricultural extension and advisory systems, affecting all market participants. The complexity of the pandemic has impacted the private sector, public sector, extension staff, donor funding, education, and research systems, subsequently affecting human nutrition. This paper aims to expertly review COVID-19’s effects on the sustainability of gender-specific agricultural extension service systems. Demand and supply market stakeholders in the extension system are thematically discussed. The findings reveal various consequences of COVID-19 for market actors on both the demand and supply sides of the extension system. Private-sector players often support expansion directly or indirectly, with multi-sectorial support and funding strategies existing for sustainability. In many developing nations, the comprehensive extension system was disrupted by COVID-19, impacting household incomes and nutrition. The pandemic accelerated the adoption of digital technologies in many developing nations, transitioning from a centralized to a decentralized and pluralistic extension model. Multi-sector coordination and execution, especially from health and other sectors, are crucial in managing complex crises that disrupt the market system.</p