Partial substitution of fishmeal with soybean meal products and derivatives in diets for the gilthead sea bream Sparus aurata (L.)

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).     

The degree of carotenoid esterification influences the absorption of astaxanthin in rainbow trout, Oncorhynchus mykiss (Walbaum)

The absorption of astaxanthin from diets (30 mg kg^?1 inclusion) supplemented with either unesterified astaxanthin; isolated astaxanthin monoesters, diesters or a cell‐free carotenoid extract from Haematococcus pluvialis were studied in rainbow trout (>200 g). No significant differences (P > 0.05) were recorded in the apparent digestibility coefficients (ADC) (≈60–65%) between astaxanthin sources. However, following consumption of a single meal, peak serum astaxanthin levels at 32 h (≈1.0–1.6 μg mL^?1) were significantly higher (P < 0.05) in fish fed unesterified astaxanthin and astaxanthin monoester, compared to fish fed astaxanthin diester and the cell free extract. However, no significant differences (P > 0.05) were recorded in serum astaxanthin uptake rates between sources of astaxanthin. Results suggest that the extent of carotenoid esterification negatively influences the peak serum levels of astaxanthin in rainbow trout.     

Analysis of Stress-Induced Gene Expression in Trout Red Blood cells following Tributyltinchloride Exposure

Submicromolar concentrations of tributyltinchloride (TBTC), an organotin compound, is able to impair mitochondrial activity in trout erythrocytes, as detected by ultrastructural transmission electron microscopy investigations and exhibits pro apoptotic activity in a variety of cells including nucleated red blood cells. Here we show that TBTC is able to induce the expression of hsp70 in rainbow trout (Onchorynchus mykiss) erythrocytes in a time- and dose-dependent manner. This induction was demonstrated by quantification of the relative abundance of mRNA, and the synthesis of hsp70 was detected by means of an immunological test. This study could provide a practical assay of environmental stress at sublethal toxicant concentrations.     

Efficacy of egg surface disinfectants in captive spawning Atlantic cod Gadus morhua L. and haddock Melanogrammus aeglefinus L.

In an effort to optimize the efficiency of high‐density incubation of Atlantic cod Gadus morhua and haddock Melanogrammus aeglefinus eggs, the per cent hatch of eggs treated with four disinfectants (3% hydrogen peroxide, 1% polyvinylpyrrolidone iodine, 0.1% sodium hypochlorite and a 0.005% antibiotic solution – penicillin/streptomycin) was compared in both species. The per cent hatch of eggs of each species was greatest after a 24 h treatment with the antibiotic solution. The hatching success of eggs treated within the different disinfectant treatments depended upon the embryonic developmental stage in both species. The sodium hypochlorite treatment had the lowest % coverage of colony growth after disinfected haddock eggs were plated onto sterile agar media, highest survival rates to the end of the embryonic period, but the lowest per cent hatch.     

The response of thick-lipped grey mullet, Chelon labrosus (Risso), to diets of varied protein-to-energy ratio

Six experimental diets were designed containing two lipid levels (approximately 12% and 24%) and three protein levels (approximately 38%, 49% and 59%) with protein-to-energy ratios ranging from 19.72 to 29.83 mg protein kJ^-1 gross energy. At both lipid levels, an increase in the protein content of the diet was achieved by decreasing the carbohydrate input. After 84 days of feeding to appetite, the fish (juvenile thick-lipped grey mullet, Chelon labrosus (Risso)) fed the high-oil diets of low and medium protein content were significantly larger than those fed low-lipid diets containing similar amounts of protein. The greatest weight gain and optimum apparent net protein utilization (ANPU) were recorded for the fish fed the diet with a P:E ratio of 19.72 mg protein kJ^-1 gross energy. At both lipid levels, increasing dietary protein supplementation led to a decrease in voluntary feed consumption and ANPU. Whole-body lipid appeared to increase in response to a higher dietary oil component. At low levels of dietary lipid, the carcass protein content increased in response to elevated protein supply. This trend was less obvious at the higher level of lipid supplementation. Hepatic glycogen deposition was significantly lower amongst the fish fed the low-carbohydrate diets at both levels of supplemental oil. A significant increase in hepatosomatic index was also recorded which was not directly correlated with either dietary carbohydrate or protein:energy level. It can be concluded from the present experiment that the optimum protein-to-energy ratio for C. labrosus juveniles is in the order of 19.72 mg protein kJ^-1 gross energy when fed the present diets containing 37.9% crude protein and 22.8% lipid. Additionally, for this species, lipid was seen as a more effective source of non-protein energy than a corn starch/dextrin mixture.     

A review of the official sampling of flocks of laying hens in the Salmonella National Control Programme in Great Britain

1. In line with European legislation and the UK National Control Programme for Salmonella, poultry farms are sampled to establish their Salmonella status. Regular samples are collected by the farmer (operator), with annual routine (official) samples being collected by the competent authority to verify achievement of the Salmonella programme reduction target.

2. To confirm sampling was being carried out effectively, a questionnaire-based survey was conducted. The aim was to identify any complicating factors the samplers encountered and the decisions made in these circumstances.

3. There was good compliance with the official sampling visits, with few delays reported. However, farm-specific clothing/separate boots for non-caged houses were rarely provided by the operator, whereas boot dips and hand washing facilities were usually available. The collection of dust was often a problem for official samplers, operator boot swabs were not always moistened before sampling and both sampler groups did not always follow the recommended method for the collection of faeces from belts and scrapers.

4. Overall, there was a good application of the sampling protocol, although a few areas for improvement were identified.     

Detection of the Matrix Metalloproteinases MMP‐2 and MMP‐9 and Tissue Inhibitors of Metalloproteinases TIMP‐1 and TIMP‐2 in Llama (Lama glama) Oviduct

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) are involved in several reproductive events like oocyte–spermatozoa interaction and semen liquefaction. In order to study their role in the llama oviductal reproductive process, MMP activity in oviductal fluid (OF) was assayed. Considering that llama genome sequences are partially known, a strategy to procure cDNA sequences of MMP‐2, MMP‐9, TIMP‐1 and TIMP‐2 was designed. Afterwards, their expression patterns in the different llama oviductal segments were assayed. Gelatine zymograms detected 62 and 94 kDa protease activities that matched MMP‐2 and pro‐MMP‐9, respectively. Expression pattern analysis showed that MMP and TIMP mRNAs were present in ampulla, isthmus, utero‐tubal junction (UTJ) and papilla. Altogether, these findings support the argument that MMPs/TIMPs are produced in the oviduct and secreted into the oviductal lumen. Our results encourage further studies to elucidate the role of these proteins in reproductive oviductal events.     

Environmental DNA reveals the temporal and spatial extent of spawning migrations of European shad in a highly fragmented river basin

1. Artificial barriers on lowland rivers impede the spawning migrations of anadromous fishes, preventing access to historical spawning areas. In the cryptic European shads Alosa alosa and Alosa fallax (‘shad’ hereafter), this has resulted in population declines across their range. Conservation programmes aim to facilitate the passage of migrators over these barriers and so require baseline information on the spatial and temporal extent of current migrations.
2. Here, a shad-specific environmental DNA (eDNA) assay was used to quantify the spatial extent of shad spawning migrations in the River Severn basin, western England. This basin is characterized by the presence of multiple barriers in the lower catchment. In 2017, the eDNA assay was piloted in the River Teme, an important shad spawning tributary, and then applied in 2018 and 2019 across the lower Severn basin.
3. In all years, shad DNA was detected between mid-May and mid-June, with the maximum spatial extent of shad distribution being in early June when shad eDNA was detected upstream of weirs that were generally considered as impassable. In 2018, this included the detection of shad above the most upstream weir on the main River Severn that required individual fish to have passed six weirs.
4. Although barriers inhibit the spawning migrations of shad, this eDNA assay showed that some highly vagile individuals might be able to ascend these barriers and migrate considerable distances upstream. This suggests that efforts to increase the permeability of these barriers could result in relatively high numbers of migrating shad reaching upstream spawning areas. These results demonstrate that this eDNA assay could also be used across their range, to further quantify the spatial extent of their spawning, including in highly fragmented rivers and those where shad are believed to spawn only occasionally and are rarely observed.

     

Genetics of genetic conservation. I. Sample size when collecting germplasm

Summary A sample of about 172 plants, drawn at random from a population of a target species, is of sufficient size to conserve at a very high probability, all or very nearly all of the polymorphic genes that are segregating in the population, provided that their frequency is not less than 0.05, irrespective of whether the individuals of the species set all of their seed by self-or by cross-fertilisation or a mixture of both. When samples are taken from a number of populations, the size of the sample drawn from each need be no larger than 172 divided by the number of populations visited. It is pointed out that implementation of this conclusion could lead to very considerable saving of resources in both the collection and storage of material in gene banks.