Optimising codend configuration in a multispecies demersal trawl fishery

Abstract The relative efficiencies and selectivities of conventional and modified codends were examined in a demersal trawl fishery targeting several species, including eastern king prawns, Penaeus plebejus (Hess), whiting, Sillago spp. and cephalopods. The modifications to codends included: (i) reducing the circumference; (ii) increasing the mesh size in conventional diamond‐mesh designs; and (iii) orientating meshes on the bar so that they were square shaped. The codends were tested against a fine‐meshed control in paired comparisons onboard three commercial trawlers. The conventional codend comprised 41‐mm diamond‐shaped mesh attached to an anterior extension section at a ratio of 150 to 100 meshes and was demonstrated to be non‐selective for the targeted species. Reducing codend circumference to 100 meshes and increasing the size of mesh to 45 mm both improved selection for eastern king prawns, but the lateral mesh openings were estimated to be insufficient to allow juveniles of the other key species to escape. By contrast, codends made from 35‐ and 41‐mm mesh hung on the bar improved the size selection for eastern king prawns and selected stout whiting, Sillago robusta (Stead) (the smallest commercial‐sized fish) across narrow selection ranges and at 50% sizes of retention (L₅₀s) that were closely correlated to the transverse morphology of fish and the maximum mesh opening. With the exception of a reduction in catches of octopus, Octopus spp., by the 41‐square codend, there were no other impacts on commercial catches by the square‐mesh designs. It was concluded that diamond‐mesh codends are inappropriate for use throughout this multispecies fishery and that a modified design comprising at least 35‐mm mesh hung on the bar is required to minimise the fishing mortality of unwanted sizes of the key target species. The results are discussed in terms of the utility of these types of modifications for closely regulating selection in penaeid‐shrimp trawls.     

Non-specific immunity parameters and the formation of advanced glycosylation end-products (AGE) in rainbow trout, Oncorhynchus mykiss (Walbaum), fed high levels of dietary carbohydrates

The effects of long-term hyperglycaemia (5 months), through feeding high levels of dietary carbohydrates, on the non-specific immunity parameters of rainbow trout, Oncorhynchus mykiss (Walbaum), was assessed. Fish were fed one of three diets composed of a basal diet containing ≈ 14% digestible carbohydrate which was progressively diluted with gelatinized potato starch in the following ratios of basal diet to supplemental carbohydrate (gelatinized potato starch): 65:00, 65:20, 65:35. The three diets were pair-fed based on the feed intake of the fish fed the diet containing the highest level of starch (65:35) and representing 100% intake. The other diets were then fed at different levels in a manner that allowed all the groups of fish in the same block to receive the same amount of the basal diet [e.g. the basal diet (undiluted, 65:00) was fed at 65% of the dietary intake of the 65:35 diet]. Blood glucose concentrations and relative liver-to-body size increased with increased dietary carbohydrate intake. Feeding supplemental carbohydrates resulted in a small increase in weight gain of the fish at both supplemental levels. Pronephros tissue lysozyme activity and pronephros macrophage superoxide production were not affected by the dietary treatments. The results suggest the presence of advanced glycosylation end-products in muscle tissue collagen, but were not significantly different between treatments. No substantial effect of long-term feeding of a high carbohydrate diet on the non-specific immunity of rainbow trout was observed. However, the results suggest that dietary carbohydrates may have a slight stimulatory effect on phagocytosis at low–moderate levels.     

Fucose-Rich Sulfated Polysaccharides from Two Vietnamese Sea Cucumbers Bohadschia argus and Holothuria (Theelothuria) spinifera: Structures and Anticoagulant Activity

Fucosylated chondroitin sulfates (FCSs) FCS-BA and FCS-HS, as well as fucan sulfates (FSs) FS-BA-AT and FS-HS-AT were isolated from the sea cucumbers Bohadschia argus and Holothuria (Theelothuria) spinifera, respectively. Purification of the polysaccharides was carried out by anion-exchange chromatography on DEAE-Sephacel column. Structural characterization of polysaccharides was performed in terms of monosaccharide and sulfate content, as well as using a series of non-destructive NMR spectroscopic methods. Both FCSs were shown to contain a chondroitin core [→3)-β-d-GalNAc-(1→4)-β-d-GlcA-(1→]_n bearing sulfated fucosyl branches at O-3 of every GlcA residue in the chain. These fucosyl residues were different in pattern of sulfation: FCS-BA contained Fuc2S4S, Fuc3S4S and Fuc4S at a ratio of 1:8:2, while FCS-HS contained these residues at a ratio of 2:2:1. Polysaccharides differed also in content of GalNAc4S6S and GalNAc4S units, the ratios being 14:1 for FCS-BA and 4:1 for FCS-HS. Both FCSs demonstrated significant anticoagulant activity in clotting time assay and potentiated inhibition of thrombin, but not of factor Xa. FS-BA-AT was shown to be a regular linear polymer of 4-linked α-L-fucopyranose 3-sulfate, the structure being confirmed by NMR spectra of desulfated polysaccharide. In spite of considerable sulfate content, FS-BA-AT was practically devoid of anticoagulant activity. FS-HS-AT cannot be purified completely from contamination of some FCS. Its structure was tentatively represented as a mixture of chains identical with FS-BA-AT and other chains built up of randomly sulfated alternating 4- and 3-linked α-L-fucopyranose residues.     

Probiotics-induced Changes in Intestinal Structure and Gut Microbiota Are Associated with Reduced Rate of Pimpled Eggs in the Late Laying Period of Hens

Production of pimpled or sandpaper-shelled eggs (SE) is a major problem in aged hens. Probiotics can improve eggshell quality; however, the relationship between SE production and gut bacteria remains unclear. Here, 1200 450-d-old Hy-line hens were assigned to four groups (300 hens each), with the control group fed basal diet and treatment groups fed basal diet plus 500, 1000, and 1500 mg/kg of Clostridium butyricum and Bacillus subtilis, respectively. After 4 weeks, probiotics significantly decreased the SE rate from 42.51% to 28.02%. To address why probiotics reduced SE rate, the hens that only produced normal eggs (NE) or SE based on a 2-week assessment were assigned to three groups (NE, SE, and SEP groups; 10 hens each), with the NE and SE groups fed a basal diet and SEP group fed a basal diet plus 1000 mg/kg probiotics. After 4 weeks, ileal tissues from eight birds/group were collected for histomorphological and gene expression analyses, and the ileal content was collected from five birds/group for 16S rDNA sequencing analysis. The data showed that probiotics significantly increased the villus length and ratio of villus length to crypt depth. Quantitative PCR analysis indicated that there were no significant differences in the expression of genes related to tight junctions, nutrient transport, and calcium absorption among the groups (except TRPV6, P<0.001). The 16S rDNA sequencing analysis indicated that the alpha-diversity of gut bacteria in the SEP group was the highest among the groups. The Firmicutes phylum was dominant in the NE and SEP groups, whereas the Proteobacteria phylum was dominant in the SE group. Together, these results suggest that probiotics can significantly influence the intestinal structure and composition of the intestinal microbiota, which may lead to a reduction in the SE rate in aged hens.     

向镰刀菌毒素污染的谷物添加葡甘露聚糖对初产母猪生产性能和血液生化指标的影响

研究表明,镰刀菌毒素会导致泌乳母猪的采食量和日增重下降,具有延长母猪从断奶至发情间隔时间的倾向;葡甘露聚糖能够防止由镰刀菌毒素毒性作用引起的血清尿素和总蛋白浓度的下降。     

植酸酶对不同类型的断乳仔猪日粮粗蛋白、氨基酸和能量的消化率的影响

通过对4个安装了简易T型瘘管的断奶仔猪研究表明,添加植酸酶并没有提高玉米-豆粕型日粮(试验组1)、小麦-豆粕型日粮(试验组2)和大麦-豌豆-菜籽粕型日粮(试验组4)粗蛋白和氨基酸的回肠表观消化率(AID),而使小麦-豆粕-菜粕型日粮的粗蛋白和氨基酸回肠表观消化率或粗蛋白和消化能的总消化道表观消化率(ATTD)得到了显著的提高(P<0.05)或呈提高的势态(P<0.10)。这些结果表明,氨基酸对细菌性植酸酶的反应因子取决于日粮的组成。     

印度Leh地区沙棘叶中脂肪酸的含量

本文用气相色谱仪分析了印度Leh地区沙棘叶油中种脂肪酸的含量,结果显示：该地区沙棘叶油中富含硬脂酸,其值可以达到13．853％,山嵛酸13．938％,亚油酸7．579％,掬焦油酸6．638％,十八稀酸4．622％。     

A test method for resistance to stem mottle in potatoes

In breeding for resistance to stem mottle in potatoes there is a need for a rapid testing and selection method. Following the method normally used with X- and Y-virus, seedlings in the cotyledon stage and young plants of potatoes were inoculated with the stem mottle virus (= rattle virus). In this way it seems possible to test and to select young seedlings for resistance. In addition it is possible to establish rapidly the resistance of known potato varieties and progenitors with the air of young plants.