Osmoregulation,growth and moulting cycles of the giant freshwater prawn (Macrobrachium rosenbergii) at different salinities

The giant freshwater prawn, Macrobrachium rosenbergii, is a species with a high commercial value in aquaculture. Two experiments were performed to determine the effects of salinities on the osmoregulation, growth and molting cycles of M. rosenbergii during growout. The first experiment was designed to determine whether these animals are capable of adapting to the changes in salinity seen in salinity intrusions in tropical deltas, with an incremental increase in salinity of 3‰ per day from 0‰ to 30‰ Haemolymph osmolality was rapidly regulated up to salinities of 15‰ , whereas animals conformed at higher salinities. The second experiment determined the growth, moulting cycle, osmolality, muscle water content and mortality during a 4‐month experiment at 0‰, 15‰ or 25‰ salinity. The weight gains in 0‰ and 15‰ were not significantly different and were comparable to the growth rates achieved in production farms with body mass increases of 2.6 and 2.3‐fold their initial body mass, respectively, after 4 months. The 25‰ group suffered from low growth, high mortality and a significantly lower moulting frequency. These data show that this species can be reared in brackish water up to 15‰, allowing for farming in the large areas impacted by salt water intrusions in tropical deltas.     

Water and nutrient budgets of ponds in integrated agriculture–aquaculture systems in the Mekong Delta, Vietnam

A participatory on-farm study analysed water and nutrient budgets of six low and four high water-exchange ponds of integrated agriculture–aquaculture (IAA) farms in the Mekong delta. Water, nitrogen (N), organic carbon (OC) and phosphorus (P) flows through the ponds were monitored, and data on fish production and nutrient accumulation in sediments were collected during a fish culture cycle. Results showed that, on average, only 5–6% of total N, OC or P inputs introduced into ponds were recovered in the harvested fish. About 29% N, 81% OC and 51% P accumulated in the sediments. The remaining fractions were lost through pond water discharges into adjacent canals. Fish yields and nutrient accumulation rates in the sediments increased with increasing food inputs applied to the pond at the cost of increased nutrient discharges. High water-exchange ponds received two to three times more on-farm nutrients (N, OC and P) while requiring nine times more water and discharging 10–14 times more nutrients than the low water-exchange ponds. Water and nutrient flows between the pond and the other IAA-farm components need to be considered when optimizing productivity and profitability from IAA systems.     

The effect of DL-methionine, N-hydroxymethyl-DL-methionine calcium salt (Mepron) and DL-methionine hydroxy analog calcium salt (MHA) on the N-deposits of calves

Digestibility and N balance experiments with calves showed that the methionine requirement of the host animal is covered by microbial protein synthesis even in the already ruminant animal. A supplement of the ration with DL methionine is only effective when it is provided in milk replacer. The MHA substitution of the ration has only little influence on N retention, independent of its supply in milk replacer or concentrated feed. MEPRON proved to be the most effective methionine derivative. As supplement both with the fluid feed and with the concentrated feed this compound shows exclusively positive results even in already ruminant calves with regard to live weight gain, N retention and the content of free methionine in the blood serum of the test animals.     

A comparative evaluation of parasitological tests and a PCR for Trypanosoma evansi diagnosis in experimentally infected water buffaloes

In this study five parasitological methods and a polymerase chain reaction (PCR) were compared for the diagnostic sensitivity for Trypanosoma evansi in experimentally infected water buffaloes over a period of 15 weeks. The combined estimates of sensitivity (CE(se)) of the PCR proved to be highest at 78.2%, closely followed by the mouse inoculation (MI), the micro-haematocrite centrifugation technique (MHCT) and the mini-anion-exchange centrifugation technique (MAECT) with CE(se) of, respectively, 74.0, 69.6 and 62.4%. The CE(se) of the buffy-coat technique (BCT) at 38.6% and the sodium dodecyl sulfate (SDS) clarification technique at 25.1% were considerably lower. PCR detected consistently all buffaloes infected from week 3 post-infection (PI) onwards. For MI this occurred after 5 weeks PI while for MHCT and MAECT these sustainable high levels were reached in the 7th week PI. BCT and SDS never detected all buffaloes infected. The influence of time and temperature on the viability of T. evansi in heparinized blood from water buffalo was also studied. In general we observed that the survival time tends to be longer when blood is kept at 4 degrees C. In samples kept in direct sunlight parasites became undetectable with the MHCT after 30min. After treatment of the water buffaloes with diminazene aceturate, the PCR signal disappeared within 24h.     

Evaluation of Diagnostic Tests for <Emphasis Type="Italic">Trypanosoma evansi</Emphasis> in Experimentally Infected Pigs and Subsequent Use in Field Surveys in North Vietnam and Thailand

This study is concerned with the evaluation of established diagnostic tests for diagnosis of Trypanosoma evansi in pigs. The immune trypanolysis test (TL), card agglutination test (CATT), latex agglutination test (LATEX), enzyme-linked immunosorbent assay (ELISA), microhaematocrit centrifugation technique (MHCT) and mouse inoculation (MI) tests were initially evaluated in experimentally infected fattening pigs. All infected pigs were confirmed parasitologically positive with both MHCT and MI. Results of the serological assays indicated that the TL could be a reference test for the presence of RoTat 1.2 antibodies in pigs. The results of the CATT and LATEX were inconsistent with the TL while the ELISA results correlated with the TL results. The four serological assays were subsequently used in two field surveys in Vietnam and Thailand. Results of the two agglutination assays (CATT and LATEX) were not consistent and did not correlate with TL results. The ELISA at percentage positivity of 22 appeared to have good ability to discriminate between seropositive and seronegative animals. Of the 437 samples collected at smallholder pig premises in northern Vietnam, no positive pigs were detected with the TL test. In Thailand, 77 samples were collected from five farrowing farms with a history of surra. Two parasitologically positive sows were found and on each farm seropositive sows were detected.     

Short Communication Prevalence of Trypanosoma evansi in Water Buffaloes in Remote Areas in Northern Vietnam Using PCR and Serological Methods

Tropical Animal Health and Production -     

固态发酵酶制剂充分释放水产饲料中潜在的营养物质

1 前言 亚太地区的水产养殖业面临许多挑战．饲料是人们关注的重点之一。饲料原料价格上涨．某些原料供应短缺以及质量降低已导致饲料原料市场的动荡和变化不定：植物蛋白原料已不再是笃定的饲料蛋白来源：生物燃料的乙醇工业与动物养殖业竞争原料．已大大改变了饲料原料的成本结构。寻求可替代的饲料原料．饲料利用最佳化和动物生产最佳化的技术．以及减少营养物质排泄和减少饲料浪费的技术在当今的水产养殖和水产饲料配方中起着越来越重要的作用。     

羊驼皮肤结构基因（原）胶原的表达特点

为了揭示羊驼皮肤胶原蛋白（Collagen）在皮肤结构发生中的分子机制,本研究通过构建羊驼皮肤cD—NA文库并进行大规模测序分析,结果表明：在羊驼皮肤内发现只有纤维类胶原表达,即typeⅠ,typeⅢ,typeⅤ collagen,其中typeⅠ表达最高,typeⅢ和typeⅤ表达低;然而,在羊驼皮肤内未发现各类collagen相对应的原胶原（procollagen）,其成员procollagentype Ⅰ,typeⅢ,typeⅣ,typeⅥ,typeⅦ,typeⅩⅧ在表达,且typeⅠ远远高于其他家族成员的表达,由此推断collagen和procollagentypeⅠ在羊驼皮肤结构发生中起主要作用,羊驼皮肤内的蛋白水解机制可能使procollagen产生不同类型的collagen。