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Notes: The effect of changing feeds on individual feed intake and feeding and dominance ranks in groups of African catfish Clarias gariepinus was investigated. Following feeding on a commercial feed groups (n = 3) of six African catfish were either fed fish meal (FM42) or maize gluten (MG35) based feeds for 5 days before being switched to the other feed for 5 days. Energy intake was significantly lower on FM42 than on MG35, dry matter intake and protein intake were significantly lower on FM42 than on commercial feed and this occurred whether FM42 was fed first or second. There were no significant differences between intake of MG35 and commercial feed. Thus, the action of changing the feed on its own did not affect feed intake since the decrease was shown to be feed-specific to FM42. Six types of agonistic behaviours were identified and used to assign dominance rank. There were no correlations between dominance and feeding ranks. This was due to non-linear hierarchies with one dominant fish in each group. Feeding ranks were more stable when feeding MG35 than FM42. Feeding rank stability (Kendall's coefficient of concordance) was significant in five out of six groups fed MG35 (compared with three out of six fed FM42). Feeding rank stability was higher in five out of the six groups when they were fed MG35 than when the same group was fed FM42. The experiment provided evidence that the introduction of a novel feed can, but does not necessarily, alter feed intake and that feed can influence the stability of feeding ranks.

Notes: Abstract The Joggins Formation was deposited in the Cumberland Basin, which experienced rapid mid-Carboniferous subsidence on bounding faults. A 600 m measured section of coastal and alluvial plain strata comprises cycles tens to hundreds of metres thick. The cycles commence with coal and fossiliferous limestone/siltstone intervals, interpreted as widespread flooding events. These intervals are overlain by coarsening-upward successions capped by planar-based sandstone mounds, up to 100 m in width that represent the progradation of small, river-generated delta lobes into a standing body of open water developed during transgression. The overlying strata contain sand-rich heterolithic packages, 1–8 m thick, that are associated with channel bodies 2–3 m thick and 10–50 m wide. Drifted plant debris, Calamites groves and erect lycopsid trees are preserved within these predominantly green-grey heterolithic sediments, which were deposited on a coastal wetland or deltaic plain traversed by channel systems. The cycles conclude with red siltstones, containing calcareous nodules, that are interbedded with thin sandstones and associated with both single-storey channel bodies (1–1·5 m thick and 2–3 m wide) and larger, multistorey channels (3–6 m thick) with incised margins. Numerous channel bodies at the same level suggest that multiple-channel, anastomosed river systems were developed on a well-drained floodplain. Many minor flooding surfaces divide the strata into parasequences with dominantly progradational and aggradational stacking patterns. Multistorey channel bodies are relatively thin, fine grained and modestly incised, and palaeosols are immature and cumulative. The abundance and prominence of flooding surfaces suggests that base-level rise was enhanced, whereas the lack of evidence for abrupt basinward stepping of facies belts, coupled with the absence of strong fluvial incision and mature palaeosols, suggests that base-level fall was suppressed. These architectural features are considered to reflect a tectonic architectural signature, in accordance with the high-subsidence basinal setting. Evidence for restricted marine influence and variation in floral assemblages suggests modulation by eustatic and climatic effects, although their relative importance is uncertain.

Notes: We have described a method for the microtransplantation of a suspension of a few thousand cells from mid to late embryonic mouse hippocampi into the fimbria of immunosuppressed adult rat hosts. There was close graft-to-host contact, across a non-scarred interface. The transplanted cells included CA3 type pyramids, and were enclosed within the host myelinated fibre tract, whose glial framework was largely undisturbed. Immunohistochemistry of two species-specific markers (M6 and Thy-1.2) showed that the donor mouse neurons grew fine (〈0.5 μm diameter) axons which extended singly or in fascicles through the rat host fimbria for a maximum distance of at least 10 mm. The donor axons were intimately integrated among and closely aligned to the host tract axons and to the interfascicular glial rows of the host tract. The axons travelled (i) laterally through the ipsilateral fimbria, (ii) medially across the midline in the ventral hippocampal commissure to reach the contralateral fimbria and alveus, and (iii) rostro-medially to the septum. On approaching the terminal fields appropriate to hippocampal CA3 pyramidal cell axons, the transplant axons gave rise to fine preterminal branches which were continuous with a reticular or amorphous immunoreactivity in the stratum oriens and stratum pyramidale of the ipsilateral hippocampus, and in the lateral and triangular septal nuclei. The donor axons extended along the host fimbria at a rate of ∼ 1 mm per day, reaching their terminal field destinations by ∼1–2 weeks. At 7 weeks the projections were maintained, but with little further extension. These observations indicate that the microenvironment of myelinated adult fibre tracts is permissive for an abundant and rapid growth of axons from transplanted embryonic cell suspensions. These axons can leave host tracts to invade appropriate terminal fields.

Notes: Gilthead seabream, Sparus aurata L., fed diets of equal vitamin C content were exposed to three different stressors–hyposalinity, shallow water and handling–and the effect of each on the internal homeostasis of the fish was evaluated. The individuals subjected to hyposaline stress exhibited no significant changes in plasma osmolality. Na+. Cl- K+, glucose, protein and triglyceride concentrations. Hepatic glycogen content was significantly lower in the fish subjected to the lower salinity (12%o), while the red muscle glycogen was unaltered. Amongst the challenged individuals, tissue ascorbate content was not significantly altered. Shallow water stress significantly diminished the liver and red muscle glycogen content, and lowered the liver. kidney and spleen vitamin C concentrations in the stressed fish. No significant changes were recorded in the plasma glucose, protein and triglyceride concentrations. In response to handling stress, no significant differences were detected in any of the measured parameters, with the exception of plasma glucose levels and the splenic L-ascorbic acid and ascorbate-2-sulphate (vitamin C2) contents. The lack of existing standardization of both experimental designs and analytical methods made comparisons of the present data with the work of other authors difficult, thus highlighting the necessity of coordinated research in this field.

Notes: Over a 56-day feeding period, during which juvenile African catfish, Clarias gariepinus (Burchell) increased in body weight at least threefold, diets containing fresh or rancid oils (0.352 and 9.133 mmol MDA equivalents per g oil, respectively) at two levels of supplemental vitamin E (20 or 100 mg all-rac-α-tocopheryl acetate kg-1 dry diet) were fed at 3% body weight per day. On termination of the feeding trial, growth performance and food utilization were assessed. Additionally, health criteria such as hepatosomatic index (HSI), haematocrit, plasma haemoglobin and plasma α-tocopherol concentration were determined. Plasma α-tocopherol was seen to increase significantly (P 〈 0.05) concomitant with dietary dose of the vitamin. Oxidation of dietary lipid source was observed to cause significant depletion (P 〈 0.05) of α-tocopherol from the plasma pool on consumption of the rancid test-diets. Final body weights of the catfish revealed that vitamin E supplementation in rancid diets significantly improved growth (P 〈 0.05), although supplementation into fresh-oil diets did not result in appreciable benefits in terms of final attained weight (P 〉 0.05). Values of other growth parameters and nutrient utilization indices were seen to respond positively to increased vitamin E levels and fresher dietary oils. With respect to other health indices, HSI was strongly correlated (P 〈 0.05) to dietary vitamin E dose and not oil oxidation state, with catfish fed lower α-tocopherol doses exhibiting larger livers proportional to somatic mass. Haematocrit values were significantly (P 〈 0.05) lower in fish fed low-tocopherol/fresh-oil diets. Although no measurably significant differences were found between treatments with respect to plasma-haemoglobin concentration, higher mean values for the fish fed rancid oils at the lower α-tocopherol inclusion level may indicate heightened Spontaneous haemolysis in this group. Mechanisms to account for dietary modulation of health indices in catfish under the present dietary regime are postulated. It was concluded that supplemental α-tocopheryl acetate in diets likely to undergo oxidation, would protect catfish from the nutritional stress imposed by rancid oils and increase growth above levels associated with unsupplemented dietary treatments.

Notes: Histological examination of liver tissue originating from juvenile European sea bass (Dicentrarchus labrax L.), fed experimental diets with a varying starch source displayed significant changes in general morphology and glycogen distribution. Fish fed diets containing a graded inclusion of a pea seed meal showed clear evidence of enhanced glycogen deposition in the liver compared to fish receiving a semi-purified starch source in the control diet. Lipid accumulation was also more evident in this group and the general architecture of the livers was noticeably different between the control fish and those fed diets with the pea seed meal at both levels. This was particularly relevant to the density and profile of hepatic sinusoids. The comparative features between the cultured seabass under laboratory conditions and the livers of wild fish are discussed.

Notes: Semi-purified diets containing 39% crude protein and 5% lipid were used to identify the qualitative requirement of African cattish, Clarias gariepinus (Burchell), for niacin and to characterize the pathologies associated with a deficiency of this vitamin. After 48 days of feeding, C. gariepinus supplied with the unsupplemented diet had developed severe deficiency symptoms and were subsequently withdrawn from the growth study. Niacin deficiency was characterized by feed refusal, listlessness, weight loss, poor feed utilization and high mortality. The skin overlaying the lateral line of the deficient fish became haemorrhagic and this clinical sign was accompanied by severe anaemia. After 126 days of feeding, fish fed diets containing 17.0 mg niacin kg−1 had also developed a dermopathy. but without anaemia or high mortality. The feeding of diets containing less than 33.1 mg niacin kg−1 resulted in suboptimal feed efficiency and poor protein utilisation. Allometric analysis of proximate composition indicated that carcass moisture, protein and ash were influenced by fish size, and not by dietary niacin content. However, significantly more lipid per unit of weight gain was deposited in the carcasses of fish fed the unsupplemented diet than in fish fed diets containing 17.0mgkg−1. The indicators used in the present study could not be applied to accurately determine a value for niacin requirement. However, until a more accurate assessment is performed, it is recommended that diets for C. gariepinus contain not less than 33.1 mg nicotinic acid kg−1 feed.

Notes: A 65-day study was undertaken to evaluate the utilization of lysine-supplemented wheat gluten meal as a protein source for rainbow trout, Oncorhynchus mykiss (Walbaum). The performance of the trout fed wheat gluten was compared to that of trout where protein was principally supplied using fish meal and full-fat soyabean meal. Six isonitrogenous diets (approximately 45% crude protein) were formulated. Thus, the reference diet (FS) was based on fish meal and full-fat soya bean meal while a further five diets were formulated with a mixture of wheat gluten and wheat middlings used to isonitrogenously replace approximately 75% and 57% of the full-fat soya and fish meal respectively. Crystalline l-lysine representing 0.00%, 0.29%, 0.58%, 0.87% and 1.16% of the complete diet was then added to the wheat-gluten-based diets. Optimal performance in terms of weight gain and apparent net protein utilization was achieved by the fish fed a wheat-gluten-based diet supplemented with lysine (0.58%) yielding a digestible lysine level of 1.9% of the complete feed. Within the range of supplements provided, lysine digestibility was high. However, at the highest levels of supplemental lysine the relationship between uptake and supplement level was not linear. Additionally, arginine digestibility was not affected by the level of lysine supplementation. However, amongst the wheat-gluten-based diets, optimal performance was associated with a lysine: arginine ratio of 1.1: 1.Despite a lysine: arginine ratio of approximately 1.1: 1, the overall performance of the fish fed the fish-meal-soya-based reference diet was poorer than expected. The results are discussed with respect to optimal patterns of gross and digestible amino acids, lysine-arginine antagonism and the possible relationship between antinutritional factors and the poor performance of the fish fed the fish-meal-soya-based reference diet.

Notes: This study examined the full and partial replacement of the fish meal component of practical diets with commercial poultry by-product meal (PBM) for juvenile African catfish Clarias gariepinus (Burchell 1822). Six test diet formulations were based on a low temperature Norwegian fish meal (LT94) as the reference protein source. Dietary inclusion levels of PBM at 20%, 40%, 60%, 80% and 100% substitution of total protein content were compared with the fish meal-based control diet (100% fish meal). All diets were iso-nitrogenous and isocaloric in gross terms. The results showed that there were significant differences (P 〈 0.05) between the final average weights of fish at the end of a 10-week feeding trial. Growth performance, feed intake, feed conversion ratio, protein efficiency ratio and specific growth rate were all depressed for catfish fed the highest levels of PBM diets compared with the fish meal group. It was inferred that amino acid profile and digestibility of protein were mainly responsible for these effects, together with reduced palatability. PBM may successfully replace up to 40% of the protein component in practical feeds for this species. Histological examination of liver tissue showed alterations in hepatic structure of those fish fed diets with higher levels of PBM.

Notes: Two growth trials were conducted to evaluate the nutritional quality of several soybean products as constituents in diets for the gilthead sea bream, Sparus aurata (L.). In a preliminary experiment, the fish were fed six diets containing different levels of solvent extracted soybean meal as a replacement for white fishmeal at four substitution levels: 10, 20, 30 and 40% of the fishmeal protein component. The diets supported less growth as the inclusion of soybean meal increased. However, significant reductions in growth were apparent at the 30% substitution level. All growth parameters followed the same trend. In the second experiment, six diets with 35% of the total protein contributed from differently processed soybean meals were tested. The products included three industrial full-fat meals heat processed for different periods, a solvent extracted meal and a soya protein concentrate. Protein digestibility coefficients were measured for all the experimental diets. All growth parameters of the fish fed the underheated full-fat meal, solvent extracted meal and soya concentrate were significantly lower than the control group. Protein digestibility coefficients were similar with no statistical differences (P 〈 0.05).