The effects of dietary treatment on the morphometrics and haematological characteristics in Clarias gariepinus

Fingerling of Clarias gariepinus have been reported to have an optimal protein requirement of 40%. Not much is known about the effect that varying this protein level has in the haematological characteristics (i.e packed cell volume, red blood cell count, haemoglobin concentration and mean corpuscular haemoglobin concentration) and on some landmarks measured along the fish's body. The haematological parameter are useful in assessing the effect of dietary treatment on leanness or robustness in the fish. The results of these experiment reveals that of the 17 landmarks measured on the bodies of the fish species fed dietary protein levels of no protein 11% (low protein), 29% (sub optimal) and 40% (optimal), only four of the landmarks show significant difference. Also, analysis of the haematological characteristics show significant difference in haematoant (PCV) and erthroycte count (RBC) in all the treatments

Biochemical aspects of the spoilage of prawns

Certain features characterise spoilage of sea foods, as distinct from spoilage of protein foods in general. Among sea foods spoilage differs in the crustaceans, teleosts, or elasmobranchs respectively. High levels of free amino acids concentrations are characteristic of prawns and other crustacean muscle. Changes occurring in these influence pattern of spoilage. Differences also exist in the sea prawns and prawns taken from the backwaters. Melanosis is a characteristic feature of spoilage in prawns. Observations have shown that prawns are very susceptible to spoilage at ordinary temperature, the period of absolute freshness not exceeding 4 hours, while prompt icing extends the period to 3-5 days.

Effect of mixed feeding schedule on growth and nutrient utilisation in Rohu, Labeo rohita (Ham.) fingerlings

Studies on nutrient utilisation and growth of rohu (Labeo rohita) fingerlings (3.13-4.09 g) raised on seven feeding schedules under laboratory conditions (26.3-33.5°C) showed that two days regular feeding on Diet B (high protein, 38.90%) resulted in maximum growth and protein retention efficiency. While regular feeding on low protein diet (Diet A) resulted in poor nutrient utilisation and growth of fish, high protein diet (Diet B) did not show any significant difference in growth from the mixed 2A-3B schedules but exhibited comparatively low protein retention efficiency. The other feeding schedules were 1A-2B, 1A-3B, 2A-2B and 2A-4B, where the numerical value refers to the number of days for continuous feeding of a particular diet. The diets A and B served as the controls which contained 3.40 and 3.67 kcal/g gross energy respectively. The 2A-3B feeding schedule was also found to be highly economic as an expenditure of Rs.11/- only was required for raising the body weight by one kilo as against Rs.17/- with high protein diet (Diet B) as calculated

Building climate-resilient food systems for Pacific Islands

The countries and territories of the Pacific Islands face many challenges in building the three main pillars of food security: availability, access and appropriate use of nutritious food. These challenges arise from factors including rapid population growth and urbanization, shortages of arable land for farming and the availability of cheap, low-quality foods. As a result, many are now highly dependent on imported food, and the incidence of non-communicable diseases in the region is among the highest in the world. This report summarizes: 1) the projected effects of climate change on agriculture, fisheries and aquaculture in the Pacific region; 2) adaptations and supporting policies needed to reduce risks to food production; 3) gaps in knowledge that must be filled in order to implement the adaptations effectively; 4) recommendations to fill these knowledge gaps.

Identification and culture of common diatoms as possible feed for Penaeus monodon

Diatoms were collected from Buyuan Bay, and from the hatchery tanks at Tigbauan, to determine the commonly occurring species, the feasibility of culturing these species, and the potential of these selected species as food for larval P. monodon. The commonly occurring diatoms were identified as Chaetoceros calcitrans, Navicula grimmei, Nitzchia seriata, Nitzchia closterium and Amphiprora sp. These diatoms were isolated and unialgal cultures prepared. Protein content analysis using the micro-Kjildahl method gave the following result: C. calcitrans, 11 . 78%; Nitzchia seriata, 25%; Nitzchia closterium, 30 . 5%; Navicula grimmei, 9 . 06% and Amphiprora sp. 8 . 96%. Feeding experiments were conducted to determine acceptability of the different diatom species and percentage survival of larval stages Z SUB-1 -M SUB-2 . Larvae were placed in 4-l capacity plastic containers with a stocking density of 10/l. The results of several feeding trials using the different mass-produced diatoms are summarized. From the data gathered, C. calcitrans appears to be the most promising candidate as feed for zoea and mysis stages of P. monodon. The average percentage survival of C. calcitrans was 63 . 76% for the 3 trials, and as high as 82 . 22% in the third trial. Comparatively high percentage survival of larvae was also recorded when Nitzchia seriata (48 . 17%) and Nitzchia closterium (67 . 6%) were given as feed, while both Amphiprora sp. and Navicula grimmei gave 0% survival. The poor results with Amphiprora sp. and Navicula grimmei may be due to their low protein content (8 . 96% and 9 . 06%, respectively) and the inability of the larvae to ingest them. Navicula and Amphiprora were observed to cling to the appendages of the larvae and to settle down in the medium making them unavailable to the larvae. Low survival was also noted when frozen C. calcitrans was used (14 . 25%). This may be due partly to the effect of the floculating agent (ALSO SUB-4 . 25 g/l) used in concentrating the diatoms. When protein contents of C. calcitrans, N. seriata and N. closterium are compared, the 2 Nitzchia species have relatively higher protein contents than C. calcitrans and, therefore, could be the more desirable feed candidates. However, few feeding trials were made using Nitzchia so that additional investigations will have to be done on this aspect.

Protein and amino acid requirements of warm-water fishes: a tool to efficient and low-cost fish feed production in Nigeria

Numerous investigations have utilized various semi-purified and purified diets to estimate the protein and amino acid requirements of several temperate fishes. The vast literature on the protein and amino acid requirements of fishes has continued to omit that of the tropical warm water species. The net effect is that fish feed formulation in Nigeria have relied on the requirement for temperate species. This paper attempts to review the state of knowledge on the protein amino acid requirements of fishes with emphasis on the warm water species, the methods of protein and amino acid requirement determinations and the influence of various factors on nutritional requirement studies. Finally evidence are presented with specific examples on how requirements of warm water fishes are different from the temperate species and used this to justify why fish feed formulation in Nigeria are far from being efficient

Nutritional evaluation of an indigenous low cost protein food

A study of supplementary feeding was conducted on children with a protein food (edible fish powder in the form of 'chutney') for 35 days and the effect assessed periodically. The most noticeable effect was gain in weight and mid arm circumference in children. 35% children showed a weight gain of 1 kg, 27% 0.5 kg, 21% 1.5 kg and 2.5% 2.5 kg. 48% children registered an increase in their mid-arm circumference by 0.5 cm, 16% 1 cm and 2.5% 1.5 cm. 10% children did not gain weight. However, these children had intercurrent infections like measles, whooping cough and asthma.

Soluble protein isolated from low cost fish and fish wastes

The method of preparation, composition, amino acid content, protein efficiency ratio and areas of possible application of water soluble protein isolates from low cost fish and fish wastes are discussed in detail in this communication.

Improved utilization and increased availability of fishery products as an effective control of aggravated animal protein deficiency - induced malnutrition in Nigeria

The estimated potential of Nigerian fish resources is 1,830,994 tonnes(t) whereas the demand based on per capita consumption of 12.0kg and a population of 88.5 million is 1.085 million tonnes. Supply is presently less than 500,000 tons. The gap between demand and supply have to be met through improved utilization and increased availability of fish and fishery products. The role of fish in nutrition is recognized, since it supplies a good balance of protein, vitamins and minerals and a relatively low caloric content. This paper appraises the consumption and utilisation pattern of fish in Nigeria, the spoilage of fish and prevention of losses as a means of increasing the availability of fish for human consumption and consequent control of aggravated animal protein deficiency - induced malnutrition. The paper further highlights the point that without increased landings, increased supply of fish can be achieved through reduction of postharvest loss of what is presently caught. The use of newly designed smoke - drying equipment to achieve such goal is highlighted. The paper also emphasises the need to put into human food chain those non-conventional fishery resources and by-catch of shrimp and demersal trawl fishes by conversion into high value protein products like fish cakes, fish pies and salted dried cakes

Dietary Phytase: an ideal approach for a cost effective and low-polluting aquafeed

Global fishmeal production from wild-catch sources cannot continue to increase indefinitely; suitable alternatives have to be found for sustainable aquaculture. Plant-based aquafeed seems to be the ideal alternative to this, but has its own limitations. Plant ingredients are rich in phytic acid, which reduces the bioavailability of nutrients like minerals and protein to the fish, thereby causing aquaculture pollution. Dietary phytase treatment reduces the aquaculture pollution by improving the bioavailability of nutrients, and reduces the feed cost as evident from poultry and piggery. Phytase activity is highly dependent upon the pH of the gut. Unlike mammals, fish are either gastric or agastric, and hence, the action of dietary phytase varies from species to species. In this article, the authors attempt to summarise various effects of phytase on nutrient utilization, growth of fish and aquatic pollution.

Preservation of Otolithus argenteus at low temperature

The studies provided data on the spoilage pattern of Otolithus argenteus during low temperature preservation. Changes in the total volatile bases, hypoxanthine, tyrosine, salt soluble nitrogen, non-protein nitrogen, pH, peroxide value, free fatty acids and thiobarbituric acid number along with organoleptic score have been reported. Organoleptically, fish stored at +20 degree C remained in acceptable condition upto 12 days while for those stored at 0 degree C in ice upto 19 days. Of the various indices tested Hypoxanthine, salt soluble nitrogen and total volatile bases nitrogen, in the order of merit can be used as freshness tests for refrigerated fish.

The 66 k-Da protein identified as a light meromyosin is involved in the setting of surimi

The 66 kilo-Dalton (k-Da) protein split off from the cross linked myosin heavy chain (CMHC) formed due to the setting of Alaska pollack surimi, frozen-storage of Pacific cod flesh, and vinegar-curing of Pacific mackerel mince was identified as a light meromyosin (LMM). Puncture and stress-relaxation tests showed that the actomyosin subunits (AMS) of Alaska pollack surimi, upon setting at 30°C, transformed into gel, although the elasticity of this gel was very low when compared to the gels from surimi or actomyosin (AM). Electrophoretic studies showed that the band due to LMM in the gel from AMS gradually disappeared with the progress of setting but higher molecular weight polymer did not form. The intensity of the bands due to other myosin sub-fragments decreased a little. The findings suggest that at setting temperature, LMM of MHC molecule leads to an unfolding resulting in an intramolecular aggregation through non-covalent interactions, and thus plays a significant role in the crosslinking of MHC.

Role of transglutaminase-mediated cross-linking of protein in the temperature-dependent setting of Alaska pollack surimi

During the low temperature setting of fish paste, myosin heavy chain (MHC) is polymerized to cross-linked myosin heavy chain (CMHC), which is considered to occur by the action of endogenous transglutaminase (TGase). In this study the contribution of TGase on the setting of Alaska pollack surimi at different temperatures was studied. Alaska pollack surimi was ground with 3% NaCl, 30% h2o and with or without ethylene glycol bis (β-aminoethylether) N, N, N¹,N¹- tetra acetic acid (EGTA), an inhibitor of TGase. Among the pastes without EGTA, highest TGase activity was observed at 25°C but breaking force of the gel set at 25°C was lower than that set at 30°, 35°, and 40°C. Addition of EGTA (5m mol/kg) to the paste suppressed TGase activity at all setting temperatures from 20° to 40°C. Gelation of the pastes and cross-linking of MHC on addition of EGTA were suppressed completely at 20° and 25°C, partially at 30° and 35°C, and not at all at 40°C. The findings suggested that during the setting of Alaska pollack surimi TGase mediated cross-linking of MHC was strong at around 25°C but the thermal aggregation of MHC by non-covalent bonds was strong at above 35°C. Setting of surimi at 40°C and cross-linking of its MHC did not involve TGase.

Effect of gibbing on protein hydrolysis during the ripening of salted herring at 4°C in polypropylene barrels

Effect of gibbing process on the protein hydrolysis in terms of free alpha amino nitrogen (FAN) content during the ripening of barrel salted herring at low temperature (4°C) was investigated. For this purpose North Sea herring (Clupea harengus) from north-east British coast was salted in polypropylene barrels and allowed to ripen at 4°C. This process of barrel salting was carried out for whole fish in one batch and gibbed fish in another batch. The investigation was performed by using new salt and used salt in separate barrels for each batch of experimental fish. Results of the present study show that protein hydrolysis was significantly higher in the ripened salt-herring produced from whole fish which was found to have more characteristic sensory properties than those produced from gibbed fish. Similar result (proteolysis) was obtained when the investigation was repeated for the spent herring although the spent herring fails to produce a ripened product with the desired characteristic sensory attributes, compared to those of pre-spawning herring.

Development of low-cost feed for culture of giant freshwater prawn (Macrobrachium rosenbergii de Man) in ponds

An experiment was conducted for 105 days in 12 earthen mini ponds of each 30m² size. Five different experimental diets containing 32% protein were formulated and prepared using fishmeal, shrimp meal, soybean meal, mustard oil cake, sesame meal, wheat bran and rice bran. A commercial shrimp diet (SABINCO starter-III) was assigned to treatment six and considered as the control. Prawns were stocked at the rate of 2.5 fry/m² and feed twice daily at the rate of 10% at the beginning and reduced to 8% for the last two months. The results of the experiment showed that prawn fed diets 1, 2, and 6 (control) showed significantly (P<0.05) highest weight gain among the dietary groups, while prawn fed diet 5 showed significantly lowest weight gain. The FCR values of diets ranged between 3.06 to 4.85. Prawns fed diet 1 and 6 showed significantly higher SGR, survival (%) and production among the dietary groups. The survival (%) of the prawns ranged between 46.6 to 66.6% and the production ranged between 304.5 to 563.3 kg/ha/105 days. The result of the study showed that diet containing 30% fishmeal, 5% shrimp meal, 5% soybean meal, 10% mustard oil cake, 10% sesame meal, 20% wheat bran, 18% rice bran, 1% oyster shell and 1% vitamin premix may be recommended for monoculture of M. rosenbergii.