Growth and mortality of the narrowbarred Spanish Mackerel, Scomberomorus commerson (Lacepède), in Omani waters

Length composition data from quarterly catches of Omani narrowband Spanish mackerel, Scomberomorus commerson (Lacepède), landed between 1987 and 1995 were used to estimate the growth, mortality and exploitation parameters of the stock. Non-linear least square fitting provided a complete set of von Bertalanffy growth estimates: L _∞ = 173.6 cm fork length; K  = 0.28; and t ₀ = −0.86 years. There were no seasonal differences among the growth estimates. The instantaneous natural mortalities determined by three independent methods based on life-history parameters were 0.35, 0.64 and 0.77. Seasonal total mortalities were calculated by the length converted catch curve method for evaluating seasonal exploitation ratios ( E ). The E -values exceeded 0.4, indicating overexploitation during almost all the seasons studied. This was supported by the large reduction in the total landings of S . commerson from 27 762 t in 1988 to 3265 t in 1993.     

Cage culture of the Pacific white shrimp Litopenaeus vannamei (Boone, 1931) at different stocking densities in a shallow eutrophic lake

Postlarvae of Litopenaeus vannamei were acclimated and stocked in lake-based cages at the following stocking densities: 10, 20, 30 and 40 shrimp m⁻². Another set of shrimp was stocked in concrete tanks as reference samples at 30 shrimp m⁻². Significant differences were observed among stocking densities throughout the 95-day culture. The final weight at harvest decreased with increasing stocking density: mean weights of 23.3, 15.8, 13.0, 10.9 and 14.6 g for the 10, 20, 30, 40 shrimp m⁻² and reference tanks were observed respectively. There were no significant differences in survival throughout the culture period, ranging between 69% and 77%. Daily growth rates (range: 0.11–0.24 g day⁻¹) and specific growth rates (range: 3.54–4.34%) also differed significantly among stocking densities, both increasing with decreasing stocking density. The feed conversion ratio in the cages did not differ among the stocking densities, ranging from 1.53 to 1.65. The relationship between stocking density and mean individual weight at harvest followed the equation y =81.06 x ^−0.54 ( R ²=0.938) and that of stocking density and production (in g m⁻²) is y =58.01 x ^−0.46 ( R ²=0.834).     

Dietary organic acids blend alone or in combination with an essential oil on the survival,growth, gut/liver structure and de hemato‐immunological in Nile tilapia Oreochromis niloticus

This study evaluated the effects of dietary supplementation of organic acids blend (OAB) alone or in combination with essential oil, Lippia origanoides (OAE) for Nile tilapia fed supplemented diets for 30 days. Fish (1.1 ± 0.04 g) were fed control (Control), or OAB 0.5% or OAB 0.5% + essential oil 0.125% (OAE) respectively. At the end of the experiment, samples were collected for de hemato‐immunological, histological analysis of the intestine and liver, as well as microbiology of the intestine. The pH of the diets supplemented with OAB and OAE reduced 0.92 and 0.19 respectively. The growth and FCR were unaffected by the treatments, but survival was significantly higher in the OAB treatment. Fish fed the OAB diet showed reduced concentration of total heterotrophic bacteria and Pseudomonas sp. in the intestine. Increased glucose in fish fed OAB and high number of circulating monocytes in fish fed OAE diet were observed. The anterior intestine of fish fed OAE diet showed larger number of goblet cells and increased villi height. The diet supplemented with OAB, mainly, improved the intestinal health and survival of tilapia juveniles and can be used in juvenile production.     

铁皮石斛复合饮料的研制

以铁皮石斛鲜条为主料,枳椇、葛根、枸杞等为辅料,通过单因素和正交试验筛选铁皮石斛复合饮料的配方,并对复合饮料的多糖、氨基酸及矿质元素含量进行测定。结果表明,铁皮石斛复合饮料的最佳配方为:每400 m L铁皮石斛提取液,添加枳椇提取液20 m L、葛根提取液20 m L、枸杞提取液30 m L、白砂糖70 g·L-1、柠檬酸0.3 g·L-1、黄原胶0.02 g·L-1,在25 MPa压力条件下先后均质2次,8 min/次,蒸汽杀菌20 min。制得的复合饮料多糖含量达3 770 mg·L-1,氨基酸总含量达384.39 mg·L-1,矿质元素总含量达184.93 mg·L-1,色泽呈青绿色,具有铁皮石斛和枳椇的清香,口感顺滑细腻,是一款风味独特、成分丰富的新型复合饮料。     

Replacement of de‐oiled rice bran by soaked and fermented sweet potato leaf meal: Effect on growth performance,body composition and expression of insulin‐like growth factor 1 in Labeo rohita (Hamilton), fingerlings

A 60‐day feeding trial was conducted to determine the growth performance and expression of insulin‐like growth factor 1 gene (IGF‐I gene) in Labeo rohita fingerlings fed with either raw, soaked or fermented sweet potato leaf meal (SPLM) by completely replacing de‐oiled rice bran (DORB), following a completely randomized design. Seven isonitrogenous (30%) and isocaloric (1.8 MJ/100 g) diets were prepared by replacing DORB with 50% and 100% raw, soaked and fermented sweet potato leaf meal, maintaining DORB‐containing diets as a control. Weight gain %, SGR (specific growth rate) and PER (protein efficiency ratio) were significantly (p < 0.05) higher when 100% DORB was replaced by fermented SPLM in comparison to other treatment groups. The fermented and soaked SPLM‐fed groups had registered with lower FCR value. The expression of growth regulating gene IGF‐I mRNA and RNA/DNA ratio was found to be significantly higher (p < 0.05) in soaked and fermented SPLM‐fed groups. In this study, the body protein and lipid composition did not vary significantly (p > 0.05). Hence, the study concludes that the fermented sweet potato leaf meal using Chaetomium globosum can replace 100% DORB in the diet of Labeo rohita without any detrimental effect on growth performance.     

Pathological and phylogenetic features of prevalent canine distemper viruses in wild masked palm civets in Japan

Ten wild masked palm civets infected with canine distemper virus (CDV), captured in Japan from 2005 to 2007, were histopathologically and phylogenetically analyzed. Phylogenetic analysis based on the amino acid sequences of the H protein of two CDV isolates from masked palm civets revealed that the two isolates were classified into the clade of recent isolates in Japan. Histopathologically marked lesions of virus encephalitis were present in the brain, whereas gastrointestinal lesions were absent or at a mild degree. The distribution of the lesions resembles that of recent CDV cases in dogs. Therefore, recent CDV infections in masked palm civets could be caused by recently prevalent CDV in dogs. The possibility of the masked palm civet as a spreader of CDV among wildlife is also discussed.     

Origin of Clostridium perfringens isolates determines the ability to induce necrotic enteritis in broilers

Since the ban on growth-promoting antibiotics in animal feed in the European Union, necrotic enteritis has become a major cause of mortality in broiler chickens. Despite the importance of the disease, the pathogenesis is still not completely understood. In the current study, Clostridium perfringens strains isolated from healthy flocks and isolates from outbreaks of necrotic enteritis were evaluated for the ability to cause gut necrosis in an intestinal loop model in laying hens and in an experimental infection model in broilers. High, intermediate and low alpha toxin producing strains were chosen from each isolation source. Only the isolates from field outbreaks induced necrotic gut lesions, independent of the amount of alpha toxin produced in vitro. It was also shown that alpha toxin producing isolates from calf hemorrhagic enteritis cases were not able to induce necrotic enteritis in poultry. These results suggest the presence of host specific virulence factors in C. perfringens strains, isolated from chickens with intestinal necrotic enteritis lesions.     

Cloning, nucleotide sequence and phylogenetic analyses, and tissue-specific expression of the transferrin gene in Cirrhinus mrigala infected with Aeromonas hydrophila

Transferrin partial complementary DNAs were cloned from the livers of five species in four genera of Indian carps (Indian major carp species: Labeo rohita, Catla catla and Cirrhinus mrigala; medium carp: Puntius sarana; minor carp: Labeo bata) subsequent to polymerase chain reaction amplification with published heterologous primers or self-designed primers derived from conserved regions of transferrin cDNA sequences. The partial transferrin cDNAs of the five species of carps had sizes from 624 to 633 bp (487 bp for L. rohita) and encoded an open reading frame consisting of 206–211 (162 for L. rohita) amino acids. The alignments of carp cDNA sequences showed 85–97% homology and 71–93% homology in deduced amino acid sequences. A phylogenetic tree of amino acid sequences of transferrin cDNAs from carps showed that the relationship among the four genera of Indian carps is well correlated with that derived from classic morphologic analyses. The hypothesized cleavage site and interdomain bridge of transferrin molecule were predicted for the above carp species and interestingly the cleavage site amino acid sequence was found to be conserved among all the carps. To study the tissue-specific expression of the transferrin gene, various tissues (liver, kidney, spleen, brain, muscle, testis, heart, intestine, gill and fin) from apparently healthy (control), moribund and survived C. mrigala experimentally infected with Aeromonas hydrophila infection were analyzed. Transferrin mRNA was detected only in liver RNA and to lesser extent in brain tissue out of the 10 tissues analyzed irrespective of bacterial infection.     

Short-Term Dinoflagellate Bloom in a Shrimp Pond in Bahía de La Paz,Gulf of California

From mid-August to mid-September 1998, a dinoflagellate bloom in a shrimp pond near La Paz, Baja California Sur, was studied. Daily samples were taken of phytoplankton, dissolved oxygen, nutrient concentrations, photosynthetic pigments and proteins. The bloom occurred at temperatures of 29.7 to 33.2?°C. High densities of a Scrippsiella-like dinoflagellate (15.9?×?10⁶ cells/L) occurred on the first day of sampling, reaching a peak of 249?×?10⁶ cells/L on Day 13, and declining to 4 to 7?×?10⁶ cells/L by Day 26. Chlorophyll a varied from 8.63 mg/m³ on Day 4 to 141.38 mg/m³ on Day 13. Total nitrogen varied widely (0.2–11.50 μM) while phosphates peaked only once on Day 13 (4.14 μM). Proteins ranged from 523 to 6387 μg/L; the latter value occurred two days after the maximal peak of nitrates and coinciding with the highest level of phosphates. Fertilizers added to the ponds increased nutrient concentration and stimulated phytoplankton growth. In turn, the food supply to cultured shrimp noticeably increased throughout the bloom.     

3种木质素降解菌的筛选及对构树降解的研究

[目的]筛选高效降解木质素的菌种。[方法]通过马铃薯琼脂平板培养、马铃薯液体摇瓶培养和变色反应,对采自吉文山枯木中的木质素降解菌进行了筛选,并对其降解构树的卡伯值和纤维素进行了测定。[结果]共筛选出3种对木质素降解能力较强的菌种,分别为JWS-1、JWS-2和向日葵菌核病菌。[结论]为进一步研究生物制浆奠定了基础。