Molecular ecology of two commercially important crustacean species, Nephrops norvegicus and Macrobrachium rosenbergii: Implications for the management of fisheries and aquaculture

Molecular ecology is one of the most important branches of evolutionary biology, and it uses the advantages of molecular techniques such as PCR-RFLP, sequencing, microsatellite analysis, and most recently the introduction of next generation sequencing, to address outstanding issues in the fields of population genetics and phylogeny. The genomic approach has been influential in providing new information relevant to traditional questions in ecology, such as genetic differentiation, speciation, species adaptation and others. The rationale of the present thesis was to incorporate the advantages of both the PCR-RFLP and sequencing techniques to gain information on the genetic variability of two commercially-important crustacean species, namely the Norway lobster Nephrops norvegicus and the giant freshwater prawn Macrobrachium rosenbergii. Nephrops norvegicus exhibits large morphological variability even between adjacent populations. The first objective of this thesis was to investigate the genetic variability of N. norvegicus from three localities, the Clyde Sea area and North Minch (North Sea) as well as Icelandic waters. The phylogeographic study found no significant differentiation between populations from the studied areas (FST: 0.01819). This finding is consistent with outcomes from previous studies that N. norvegicus populations were not geographically structured. Outcomes from the present study strongly suggest that environmental factors, rather than genetic factors, are more likely to play a more significant role in the high morphological differentiation observed in this species. A study of the most important freshwater crustacean species, Macrobrachium rosenbergii was then undertaken as a contribution to understanding the most complex biogeography in the world, the Indo Australian Archipelago (IAA). The IAA has incredible species richness and endemism and is the location of 4 out of 25 world’s biodiversity hotspots, namely the Sundaland, the Philippines, Indonesia and Wallacea. Within the IAA is the location of Wallace’s line and Huxley’s line, the most abrupt faunal transition in the world that lies between the Sunda and Sahul shelves. The studied species used in the present thesis, M. rosenbergii is an ideal model species as it has a wide geographical distribution across the IAA. The present phylogeographic study screened the COI segment using the sequencing technique to study M. rosenbergii populations collected from eight locations in Malaysia in the peninsular and east of Malaysia. These populations exhibited high genetic differentiation (FST: 0.62503) mainly due to the sample from Sabah. However, the adjacent population (Sarawak) was similar to that in Peninsular Malaysia, even though Northern Sarawak showed sub-population differentiation from the main cluster (cluster I) indicating that the genetic diversity of Northern Sarawak was more restricted. Beside, cluster II observed in the study indicated and confirmed the recent aquaculture activities of restocking the Kedah, Perak and Sarawak populations. Knowledge of the levels of genetic differentiation in N. norvegicus and M. rosenbergii could assist in the management of the species. N. norvegicus could be managed as one stock and conservation and recovery programme could be carried out based on the knowledge that all studied populations exhibited lack genetic differentiation within and between populations. In contrast, M. rosenbergii that possessed high level of genetic differentiation have to be managed separately, especially for a unique population such as the one in Sabah. The outcomes of this study could also be useful for future research in the conservation of wild population, as well as aquaculture management and product improvement purposes. The finding of Sabah as a unique population could potentially be useful for aquaculture improvement programmes. One of the most important aspects is to see whether Sabah population possessed high resistant to the disease infection. A preliminary study was conducted to investigate the susceptibility of a Malaysian wild population of M. rosenbergii to infection by the human food-poisoning bacterium V. parahaemolyticus. Nonetheless, the virulence stage of the bacterial strain, the status of the immune system of the host, the size and age of the experimental animals as well as the dose of injected bacteria might all have contributed to the inconclusiveness of the results. However, the principle of screening wild populations for disease resistance is sound, and may lead to improvements in the quality of the broodstock used in the Malaysian aquaculture industry

The effect of physical and biological pre-treatments of oil palm fronds on in vitro ruminal degradability

Physical pre-treatment of the oil palm frond (OPF) is known to loosen the lignocellulose while the biological pre-treatment is capable in degrading the lignin, making the substrates more accessible for rumen microbes. This study aimed at assessing the efficacy of physical, biological and combination of both pre-treatments of OPF on the in vitro ruminal degradability. Five different samples of OPF pre-treatments were used in this study; OPF was subjected to the physical pre-treatment (POPF), OPF to the biological pre-treatments using an enzyme extract of each Ganoderma lucidum (BGL) and Lentinula edodes (BLE), respectively. Another two samples were subjected to a combination of physical and biological pre-treatments of G. lucidum (CGL) and L. edodes (CLE) respectively. The control was non-treated OPF. Two fistulated Katjang goats consuming 440 g/kg OPF and 897 g/ kg commercial pellet daily on dry matter basis were used as rumen fluid donors. In vitro incubation was carried out at 39°C for 24 hours. Proportions of volatile fatty acid were measured at the end of incubation by gas chromatography. Results showed that concentrations of lignin following all pre-treatment methods were significantly lower (p<0.05) at 150(POPF), 90(BGL), 119(BLE), 100(CGL) and 120(CLE) g/ kg DM as compared to the FOPF (190 g/kg). After 24 hours of incubation, the cumulative gas of all treatment groups differed significantly from FOPF. Both BGL and CGL showed significantly higher propionate and butyrate concentrations as well as apparent rumen degradable carbohydrate with 6.57 mg and 6.54 mg, respectively as compared to the FOPF. It appeared that BGL and CGL resulted in higher lignin degradation that increased the in vitro rumen degradability. In conclusion, biological pre-treatment with enzyme extract of WRF, either alone or in combination are promising to improve the quality of OPF

Palm date meal as a non-traditional ingredient for feeding aquatic animals: A review

Protein ingredients in aquafeed are one of the most important factors responsible for the development and sustainability of aquaculture. Currently, because of high costs and fluctuating production, some animal and plant protein sources are unable to satiate the increasing demand from the fish feed manufacturers. Aquatic animals’ nutritional requirements have been accorded particular focus with less costly feedstuff in aqua feed given extra weightage. There has been increasing attention in recent years on finding methods to recycle the animal and plant by-products for feed preparation. Due to its vital amino acid content as well as high protein composition, palm date meal (PDM) which is a renewable and sustainable resource is expected to be a viable raw material option for replacing protein ingredients (e.g., fish meal and soybean meal) or as a supplement in fish feed. PDM is an agro-industry by-product which left from dates as waste in several countries. This article reviewed the current research including the source, derivatives, and the potential of PDM as a possible alternative to the conventional plant and animal protein sources. Also, the added value of using PDM waste in aquafeed to reduce the feed cost, enhance this e growth rate of fish, improve the health and well-being of fish, and subsequently sustain the aquaculture industry. Therefore, this review paper will illuminate the possibility of PDM as a promising feed source and also the present knowledge and future perspectives about the application of PDM in aquaculture

Feed Intake and Apparent Nutrient Digestibility of Growing Rabbits Fed Asystasia gangetica with Different Levels of Corn

This study investigated the effect of different corn levels on intake and digestibility in rabbits. The rabbits were divided into four groups and given Asystasia gangetica ad libitum as a basal diet and supplemented with either 80 g (T1), 60 g (T2), 40 g (T3), or 0 g (T4) corn/head/day. Rabbits fed with the T4 diet demonstrated a higher intake/kg metabolic weight than the other treatments. Nevertheless, rabbits fed with T4 and T1 diets depicted the lowest and highest digestibility, respectively. In conclusion, apparent nutrient digestibility was significantly improved in growing rabbits following supplemental feeding with a diet containing 60-80 g of corn

Fermented Soybean Meal (FSBM) in African Catfish (<i>Clarias gariepinus</i>) Diets: Effects on Growth Performance, Fish Gut Microbiota Analysis, Blood Haematology, and Liver Morphology

The study revealed the potential of fermented soybean meal (FSBM) as a fish meal (FM) replacement in African catfish (Clarias gariepinus) feed formulation. Five isonitrogenous diets (32% crude protein) were prepared with five different levels of FSBM as FM replacement, namely 0% FSBM (T1), 40% FSBM (T2), 50% FSBM (T3), 60% FSBM (T4), and 70% (T5). The experimental fish was given the formulated diet for eight consecutive weeks. At the end of the feeding trial, the fish were subjected to growth performance, blood parameters, blood chemical, liver histology, and gut microbiota assessment. The study findings demonstrated that the experimental fish that received the T2 diet exhibited significantly higher (p p p p Akkermansia muciniphila in the experimental fish that received the T2 diet. The gut microbiota indicates that the experimental fish is in a healthy condition. In conclusion, replacing 40% FSBM with FM in aquafeed could enhance C. gariepinus growth performance and health conditions

Olive oil by-products in aquafeeds: opportunities and challenges

The increment in world population has led to the increasing demands for fish supply as principal source of animal protein that represents about 17% of animal protein consumption globally. The world aquaculture industry has expanding remarkably but limited source of fishmeal and fish oil which known as important ingredients in fish feed has led to seeking of alternative sources for their replacement in aquafeed formulation. Many potential and cheaper ingredients derived from vegetable oils or agricultural by-products have been investigated to replace fish meal and fish oil which shown promising results in fish productivity and fish health status including olive oil by- products. Varies depending on its type, olive oil composes of antioxidants, healthy type of fats such as MUFA and PUFA, and high in vitamins that provide human health benefits for heart and liver, help in many diseases and reducing the risk of cancer. In agriculture industry, olive and olive oil production processes have resulted to by- products such as olive mill wastewater (OMW), olive leaf and olive pomace. The inclusion of these by-products in animal feeds is the solution for agricultural waste management. The first report of utilization of olive oil by- products in fish feed was documented in 2004 and since then, many researches has been conducted to investigate fish health benefits that showed improvement in fish carcass composition and fish immunity depending on type of by-products used and fish species. Additionally, antioxidant contents in olive oil extract were reported could provide antimicrobial, antifungal and antioxygenic characteristics which potentially improve the fish health. This review discussed the opportunities and challenges in application of olive oil by-products in aquafeed which provides significant prospects in fish growth performance that could boost aquaculture industry development

Coconut Palm: Food, Feed, and Nutraceutical Properties

The price of traditional sources of nutrients used in animal feed rations is increasing steeply in developed countries due to their scarcity, high demand from humans for the same food items, and expensive costs of raw materials. Thus, one of the alternative sources is coconut parts or coconut as a whole fruit. Coconut is known as the &lsquo;tree of abundance&rsquo;, &lsquo;tree of heaven&rsquo;, and &lsquo;tree of life&rsquo; owing to its numerous uses, becoming a very important tree in tropical areas for its provision of food, employment, and business opportunities to millions of people. Coconut contains a rich profile of macro and micronutrients that vary depending on the parts and how they are used. It is frequently chosen as an alternative source of protein and fiber. Its uses as an antibacterial agent, immunomodulant, and antioxidant further increase its importance. Using coconut oil in ruminant feed helps to minimize methane gas emissions by 18&ndash;30%, and to reduce dry matter intake up to 4.2 kg/d. The aquaculture sectors also use coconut palm as an alternative source because it significantly improves the digestion, growth, lipid metabolism, health, and antioxidative responses. However, coconut is not widely used in poultry diets although it has adequate amount of protein and carbohydrate due to anti-nutritional factors such cellulose (13%), galactomannan (61%), and mannan (26%). This review considered the importance and potential of coconut usage as an alternative ingredient in feed and supplements in various livestock sectors as it has plentiful nutrients and functional qualities, simultaneously leading to reduced feed cost and enhanced production