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In the discourse about the development of farmed animal production (terrestrial livestock production and aquaculture) in the tropics, two important food system outcomes emerge: (1) to supply animal-sourced food (ASF) at a level that suffices healthy future diets, including for poor people, and (2) to contribute to climate change mitigation and minimize pollution with nitrogen and phosphorus. Livestock production and aquaculture contribute to food security directly by increasing producers’ food diversity and availability, but also that of urban consumers, and indirectly through income generation and increased farm resilience. Recently, circularity has come to the fore as an integrated approach to food system development. Circularity has four cornerstones: (1) food crops have highest priority (which implies no food-feed competition), (2) avoid losses, (3) recycle waste and (4) use animals to unlock biomass that humans cannot eat. In this review, the role of farmed animals in circular food systems in the tropics is presented in four case studies and the impacts of circularity on food security and environmental impact mitigation are discussed. The cases are ruminants in grazing systems in West Africa and in Colombia, fish in pond aquaculture in general, and land-limited dairy production in Indonesia. Additionally, options for novel protein sources for use in livestock and fish feeding are presented. It is concluded that farmed animals are important in circular food systems because of their use of land unsuited for crop production, their upgrading of crop residues, and their supply of manure to crop production. Nevertheless, the increasing demand for ASF puts pressure on important characteristics of circularity, such as minimizing food-feed competition, maximization of use of waste streams in feed, and the value of manure for fertilization. Hence, in line with conclusions for Western countries, maximum circularity and sustainability of food systems can only be achieved by optimizing the population size of animals. Thus, a sustainable contribution of ASF production to global food security is complex and in not only a technical matter or outcome of an economic process balancing supply and demand. It requires governance for which public, private, and social actors need to partner.

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Although a stenohaline freshwater fish, the stinging catfish Heteropneustes fossilis, is also available in the freshwater fringes of the coastal areas of Bangladesh, the tolerance of this species to variable environmental salinity has not been thoroughly investigated. Based on median lethal salinity (MLS-50 96 h), three sublethal salinity levels (3 ppt, 6 ppt and 9 ppt) and a control (0 ppt), each with three replications were selected to observe the effects of mildly brackish conditions on the fish for a period of 90-day exposure. Better growth and survival were found up to 6 ppt compared with control. Salinity more than 6 ppt appeared unsuitable for H. fossilis fingerling due to increased mortality and reduced growth. To determine biochemical alterations, a few important physiological parameters were observed after 90 days of exposure. Glycogen level of liver and muscle in the fish reared at 9 ppt salinity decreased significantly (P

This study tested the effect of two diets differing in carbohydrate to lipid (CHO:LIP) ratio (4.7 vs. 19.5 g/g) on the contribution of natural food and the total fish production in tilapia ponds. Eight ponds, each divided into three equally sized compartments, were assigned to one of the two diets, which differed in CHO:LIP ratio but had the same digestible protein to digestible energy (DP:DE) ratio (15.5 and 15.6 g/MJ). Ponds were fed equal amounts of crude protein. Three feeding levels (no, low and high) were nested in each pond in a split plot design. Average body weight of fish at stocking was 90 g, and the duration of the experiment was 42 days. Increasing the CHO:LIP ratio had no impact on tilapia production. However, the feeding level influenced both biomass gain, specific growth rate and survival. The apparent digestibility coefficient (ADC) for fat and carbohydrate was influenced by dietary CHO:LIP ratio but ADC for energy was unaffected. Proximate analysis of fish body composition showed no effect of diet except for levels of ash. Diet had no effect on the organic matter composition of the faeces, and the contribution of natural food to fish nitrogen gain. Therefore, we postulate that changing the dietary non-protein energy source from lipid to carbohydrate does not have any impact on tilapia culture in semi-intensive ponds.

Dietary non-starch polysaccharides (NSP) changes the nutrient digestibility and faecal characteristics in fish. This study assessed the effect of the type of dietary NSPs on fish production and the contribution of natural food to the total fish production in semi-intensively managed tilapia ponds. Twelve ponds, each divided into three equally-sized compartments, were assigned to test the effect of the type of dietary NSPs (i.e. “PecHem-Diet”, a diet with easily fermentable NSP, vs “LigCel-Diet”, a diet with slowly fermentable NSP). Fish were restrictively fed, based on the crude protein content of the feed. Three feeding levels (“no = 0”, “low = 9 g.kg-0.8.d−1” and “high= 18 g.kg-0.8.d-1”) nested in pond were analysed in a split plot design. Initial fish biomass was 3084 g.compartment−1 and the experiment lasted 56 days. With the “LigCel-Diet” biomass gain was higher (2599 vs 2192 g.compartment−1) and feed conversion ratio (FCR) was lower (1.4 vs 1.9; P < .001) than with the “PecHem-Diet”. Diet had no effect on fish survival and specific growth rate (SGR). For both diets, increasing feeding level increased (P < .001) biomass gain, fish survival, FCR and SGR. There was a significant interaction effect (P < .05) between diet and feeding level on FCR. Fish body composition was the same in both diets. With the “LigCel-Diet”, the apparent digestibility coefficient (ADC) was higher (P < .001) for crude protein, fat, phosphorus and calcium and lower (P < .05) for ash compared to the other diet. Neither feeding level nor the interaction between diet and feeding level influenced the apparent digestibility coefficient (ADC) of any nutrient. Diet composition did not alter the organic matter (OM) composition of the faeces. δ13C and δ15N from the stable isotope analysis revealed that N gain in fish originated from both feed and natural food of the pond. Natural food abundance in the pond increased over time for both diets. Chlorophyll-a was higher in the pond fed with “LigCel-Diet”. Fish gut content and calculated N gain indicated an enhanced contribution of natural food to fish growth in ponds fed with “LigCel-Diet”. In conclusion, the type of dietary NSP determines tilapia productivity in semi-intensive managed ponds by altering food web productivity.

Estuarine aquatic systems and braided rivers in and adjacent to the Sundarbans and the vast area of the Ganges tidal floodplain next to the core forest area in Bangladesh holds rice aquatic faunal diversity and provides plenty of opportunities to grow fish, shrimps and crabs. Currently these systems provide direct employment opportunity for 1.2 million people and indirect or seasonal livelihood for more than 10 million people across the southwest coast. Hilsa is the largest fishery in this region and shrimp brings the highest cash and export earnings. Proper implementation of fisheries regulation is critical to ensure conservation of the rich fish diversity of this region as well as to continue to support livelihood of millions of people living on fisheries. While aquaculture is the major contributor to national fish production, agricultural GDP and export earning, it requires planned advancement from the current state to continue to grow in harmony with environment. Integration with rice and other crops, and with mangrove wherever possible can bring long-term sustainability of these systems. Change in the river flow due to siltation and reduced upstream flow, climate change, sea level rise, outbreak of disease in fish and crustaceans are major challenges for future growth and sustainability of both aquaculture and fisheries in this region. Collaborative and multi-disciplinary research should be undertaken to address these challenges. In addition, there should be mechanism to bring research outputs into use and make impact on sustainability.

When fish have only access to formulated feed, the optimal dietary protein to energy ratio (P:E) for tilapia ranges between 18 and 23 g.MJ−1. In pond culture, where natural foods complement administrated feed, increasing the carbon:nitrogen (C:N) ratio stimulates the natural food productivity. This study assessed if lowering the dietary P:E ratio (and thus increasing the C:N ratio of the feed input in the pond) below the optimal P:E ratio affects fish productivity, food web dynamics and nitrogen balances in semi-intensively managed tilapia ponds. Twelve ponds, each divided into three equally-sized compartments, were assigned to test the effect of two diets, which differed in P:E ratio (19 vs. 14 g.MJ−1). Three feeding levels (no, “low” and “high”) were nested in each pond in a split plot design. Initial fish biomass was 1166 (±16) g.compartment−1 and the experiment lasted 60 days. Decreasing P:E ratio enhanced tilapia production and specific growth rate (P

This study presents an overview of the existence and effects of six heavy metals, chromium (Cr), lead (Pb), cadmium (Cd), mercury (Hg), manganese (Mn), and aluminum (Al), in tannery effluents released to the Buriganga River in Dhaka, Bangladesh. The pollutants were found in three different sources, such as effluents from tanneries, contaminated river water and three species of fish—climbing perch ( Anabas testudineus), spotted snakehead ( Channa punctata), and Black tilapia ( Oreochromis mossambicus) caught from the river. Tannery effluents, water, and fish samples were collected from three different factories, five sample stations, and three different harvesting points, respectively. Effluents from all three factories contained significant amounts of heavy metals, especially Cr (374.19 ppm in average), whereas lesser amounts were found in the tissues of the three fish species studied. The trends in tissue elemental concentrations of fish were Cr > Pb > Al > Hg > Mn > Cd. In most cases (Cr, Cd, Mn, and Al), heavy metal concentrations were found to be greater in climbing perch than in Black tilapia and spotted snakehead. Although the river water contained high concentrations of harmful heavy metals, the fish species under study had concentrations well below the permissible Food and Agriculture Organization/World Health Organization levels for those metals and seemed to be safe for human consumption.

There is growing interest to understand the dietary P:E requirements for the supplemental feed used in tilapia pond culture where natural food contributes to production. In an on-farm trial, we tested the effect of lowering dietary P:E ratio on fish performance, pond nutrient utilization and economic benefit under two stocking densities and feeding levels. Forty ponds, (average size 234 ± 112 m2), were assigned to test the effect of two diets, which differed in P:E ratio (18 vs 14 g.MJ−1), two feeding levels (14 vs 18 g.kg-0.8.d−1) and two stocking densities (2 vs 3 fish.m−2). Initial fish biomass was 45(±21) vs 67(±38) g.m−2 at 2 vs 3 fish.m−2, respectively. The experiment lasted 82 days. Decreasing P:E ratio enhanced tilapia production (P < 0.05; 459 vs 399 g.m−2). Increasing stocking density of tilapia from 2 to 3 m−2 increased biomass gain 43% (P < 0.001; 354 vs 505 g.m−2). Averaged over both diets and stocking densities, growth and feed conversion ratio increased with increasing feeding level (P < 0.001). Fish survival was unaffected by diet, stocking density and feeding level. Dissolved oxygen increased with increased stocking density with low P:E diet. The opposite happened for high P:E diet (P < 0.05). Increasing the feeding level also increased the DO concentration (P < 0.001). N retention efficiency was higher with the low P:E ratio diet (P < 0.001; 71 vs 52%) and decreased with increasing feeding level (P < 0.001). The data on N gain and N balance at the pond level suggest that the food web productivity was stimulated by reducing the dietary P:E ratio. The low P:E diet increased the gross margin by 95% (P < 0.001; 2076 vs 1067 USD.ha−1) and benefit cost ratio by 22% (P < 0.05; 1.57 vs 1.29). The P:E ratio of the low P:E diet is less than the presently advised. Lowering the P:E ratio from 18 to 14 g.MJ−1 in pond feeds for tilapia will increase the economic viability of pond aquaculture.

Biodiversity conservation is one of the important ecosystem services that has been negatively impacted by anthropogenic activities. Natural forests (NF) harbor some of the highest species diversity around the world. However, deforestation and degradation have resulted in reduced forest land cover and loss of diversity. Homegarden agroforestry (AF) systems have been proven to be an intermediary for biodiversity conservation. In this study, we evaluate the effectiveness of home garden AF practices to conserve tree species diversity in Bangladesh and compare them with tree species diversity in NF. A total of nine locations were selected for this synthesis from published literature which comprised of five AF sites and four NFs. Shannon–Weiner Diversity Index (H) was similar for home-garden AF (3.50) and NF (2.99), with no statistical difference between them. Based on non-metric multi-dimensional scaling (NMDS) ordination analysis, the AF and NF plots showed distinct separation. However, Bray–Curtis dissimilarity index ranged from 0.95 to 0.70 indicating nearly no overlap in species composition to significant overlap between AF and NF. Based on our results, we conclude that AF can serve as an important ecological tool in conserving tree species diversity, particularly on landscapes where NF fragments represent only a small fraction of the total land area. Creating and maintaining AF habitats in such human dominated landscapes should be part of the biodiversity conservation strategy.

This proximate study was carried out to determine the nutrient content of six commercially important molluscs. The selected molluscan species were Pila globosa, Bellamya bengalensis , Melania tuberculata, Lamellidens marginalis, Anisus convexiusculus and Helix sp . These species were assessed for their proximate and mineral compositions designed to establish their nutritive values on the wet weight basis. The analysis of muscles revealed that the composition of crude protein varied from 8.272%±0.05% in Pila globosa to 12.927%±0.57% in Anisus convexiusculus , moisture content varied from 74.6%±0.04% in Melania tuberculata to 85.9%±0.68% in Lamellidens marginalis and in case of ash content it varied from 1.036%±0.02% in Pila globosa to 4.607%±0.01% in Anisus convexiusculus . Carbohydrate content varied from 2.902±0.03% in Pila globosa and 7.566%±0.37% in Melania tuberculata. The fat and crude fiber content was marginally small in all of the species. The concentrations of calcium, phosphorus, iron, sodium and potassium in the flesh and shells of the molluscs were determined. It becomes pretty clear that molluscs are excellent sources of some required trace and minor elements needed for the proper growth and development of human being and can also be used as high-nutrient supplementary feed for domestic animals, birds and even for fish culture. Keywords : Freshwater; Snails; Proximate analysis; Nutrition; Minerals. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i2.3362 J. Sci. Res. 2 (2), 390-396 (2010)

Using the Weinberg Lagrangian for the pion - nucleon interaction, the possibility of pion condensation in neutron matter has been investigated in detail. The constraints imposed by current algebra and the PCAC on the isospin-even, off-shell scattering amplitude have been incorporated in the model. We find that a condensate appears in the s-state at about twice the nuclear saturation density. At a higher density, such a condensation is possible in the s-state as well as in the p-state.

A calculation of the elastic scattering of mesons from /sup 16/O is performed, using a modification of the first-order multiple scattering theory of Kerman, McManus, and Thaler, in which Pauli blocking effects are omitted from the tau operator. The modified tau operator is calculated in a three-body model, in which the struck nucleon is allowed to recoil in a Woods-Saxon nuclear shell model potential exerted by the remainder of the nucleus. The interaction between the meson and the struck nucleon is described by a separable potential. A set of coupled differential equations that describe the elastic and the excited channel wave functions is derived by approximating the shell model binding potential in the excited states of the nucleon as a potential for the meson-nucleon center of mass. This approximation is examined in detail. It is found that in the three-body model the bound states and the single particle resonances of the shell model potential alter the results significantly from those obtained in impulse approximation.