Feed intake and growth of Atlantic salmon, Salmo salar L., fed diets supplemented with oxytetracycline and squid extract

This study examined the long-term effects of a feeding deterrent, oxytetracycline (OTC), and a feeding stimulant, squid extract, on feed intake, growth and dry matter (DM) digestibility in Atlantic salmon, Salmo salar L. Fish were fed one of four diets for 9 weeks: 1. commercial feed formulation (basic); 2. BM (basic plus 20 g kg⁻¹ OTC); 3. BMS (BM plus 10 g kg⁻¹ squid extract); 4. BS (basic plus 10 g kg⁻¹ squid extract). OTC initially reduced the palatability of the feed, but the fish seemed to become accustomed to the taste of OTC over time. Addition of squid extract to the medicated feed (BMS) seemed to mask the aversive taste of OTC, but the effect on feed consumption was of short duration. Addition of squid extract to the basic feed (BS) had no significant effect on feed intake, growth or feed digestibility. The growth of fish fed medicated diets (BM and BMS) was depressed, probably as a consequence of reduced feed digestibility. The two additives led only to temporary changes in feed acceptability, but both growth and DM digestibility were affected by OTC. Thus, we suggest that short-term studies may be inadequate to test whether deterrent or stimulant properties of feed ingredients are of practical importance in feed formulation.     

含土霉素土壤添加不同基质后对玉米生理特性的影响

为了解兽用抗生素污染对作物生长的潜在影响,选择四环素类抗生素土霉素作为目标污染物,通过玉米盆栽试验探讨含土霉素土壤(50mg/kg)施用不同基质(菌剂、蚯蚓粪、生物质炭等单施及其配施菌肥)对玉米生育期生物量、光合参数和酶活性的影响。结果表明:土霉素对玉米根的抑制作用大于植株,菌糠(JK)、菌剂+蚯蚓粪(JQ)和菌剂+生物质炭(JS)处理比OTC处理的玉米根长和根干重分别提高9.1%,9.4%,13.7%和66.46%,183.4%,46.72%;不同基质处理可有效减少土霉素对玉米的净光合速率、气孔导度和蒸腾速率的抑制作用;与OTC处理相比,菌剂(JK)处理均能显著提高玉米3个时期的叶绿素含量,幼苗期、拔节期和成熟期升幅依次为7.78%,33.33%和12.03%。成熟期菌剂+生物质炭(JS)处理比OTC处理分别提高玉米CAT活性48%和POD活性43.2%;幼苗期、拔节期和成熟期生物质炭(S)、菌剂+蚯蚓粪(JQ)和菌剂(JK)处理比OTC处理分别减少脯氨酸59%,16.5%和55.4%。总趋势为土霉素对玉米生长有明显抑制作用,但添加不同基质均能不同程度缓解土霉素对玉米生理特性的影响,菌糠(JK)、菌剂+生物质炭(JS)、生物质炭(S)和菌剂+蚯蚓粪(JQ)等处理优为明显。研究可为筛选减少抗生素对植物生长的基质提供理论依据,也可为土霉素对农作物的风险评价提供科学意义。     

Scale pattern analysis is preferable to OTC marking of otoliths for differentiating between stocked and wild dusky flathead, Platycephalus fuscus, and sand whiting, Sillago ciliata

A pilot programme to evaluate the effect of stocking dusky flathead, Platycephalus fuscus (Cuv. & Val.), and sand whiting, Sillago ciliata (Cuv. & Val.), began in the Maroochy River estuary in 1995. Two possible methods of mass marking; oxytetracycline (OTC) marking of otoliths, and scale pattern analysis (SPA) were investigated. A range of OTC trials was conducted, with limited success. High concentrations (1000 mg L^?1) of OTC and low salinities (≤9°/₀₀) produced acceptable marks on the otoliths of both species, but at the expense of fingerling survival and environmental health risks. SPA provided better results, with wild to hatchery misclassification rates of 25 and 11%, respectively, for P. fuscus and S. ciliata. The reverse misclassification rate of hatchery to wild was equal or better for both species. Field trials demonstrated that SPA was able to differentiate between the two sources of fingerlings (wild and hatchery). These results indicated that OTC was impractical, while SPA was acceptable for this pilot programme. The implications of these results are discussed.     

Radiological examination of the spinal column in farmed rainbow trout Oncorhynchus mykiss (Walbaum): experiments with Flavobacterium psychrophilum and oxytetracycline

Flavobacterium psychrophilum and oxytetracycline have both been associated with spinal deformities in salmonids. Experiments were carried out to investigate whether infection with F. psychrophilum or medication with oxytetracycline (OTC) at the fry stage would result in an increased occurrence of vertebral column deformities in rainbow trout, Oncorhynchus mykiss (Walbaum). Fish were on‐grown for 9 months and examined by radiology at the end of the experiments. There was a relationship between infection by F. psychrophilum and deformities of the spinal column, if fish with more than 10 affected vertebrae were classified as deformed. The deformities found among infected fish were often visible externally and were more severe than those seen among control fish (most deformities foun among controls were only seen on X‐ray photographs). Deformities were evenly spread along the vertebral column of infected fish. OTC treatments of up to 200 mg of OTC (kg fish)^?1 day^?1 for 10 days and repeated three times did not result in increased spinal deformities relative to untreated control groups; therefore, medication of rainbow trout with oxytetracycline did not cause deformities of the spinal column under our treatment conditions.     

Beneficial effects of thyme (Thymus vulgaris) extract on oxytetracycline‐induced stress response,immunosuppression, oxidative stress and enzymatic changes in rainbow trout (Oncorhynchus mykiss)

The aim of the present study was to investigate the effects of thyme extract (TE) and oxytetracycline (OTC) on rainbow trout (Oncorhynchus mykiss) stress response, immune parameters, oxidative stress and enzymatic changes. The fish were assigned into eight treatments receiving diets with OTC (0 and 2.5 g/kg) and TE (0, 5, 10 and 20 g/kg) for 2 weeks. Thereafter, serum characteristics and gut oxidative status were evaluated. OTC significantly increased serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities, and cortisol and glucose levels; however, TE significantly suppressed these changes. OTC significantly decreased, but TE significantly increased gut catalase (CAT) and glutathione peroxidase (GPx) activities. OTC significantly decreased gut superoxide dismutase (SOD) and increased gut glutathione‐s‐transferase (GST) activities, malondialdehyde (MDA) content and blood monocyte percentage; TE significantly mitigated these changes. TE significantly increased serum total protein, total Ig, lysozyme and ACH50, and blood WBC; however, OTC significantly decreased serum lysozyme and ACH50 activities and blood WBC and neutrophil percentage. In conclusion, OTC administration causes immunosuppression, which might be related to deterioration of fish health. TE augments trout innate immune and antioxidant status and is capable to counteract OTC‐induced health and immune deterioration.     

兽药土霉素的环境行为研究进展

兽药残留的生态毒理学效应已受到越来越多的关注.土霉素以是养殖业中广泛使用的广谱抗菌药之一,进入畜禽体后,土霉素原形及其体内代谢产物会随粪尿等排泄物进入环境,给环境带来风险.论文首先介绍了土霉素在环境中残留的主要形式及其理化性质,包括土霉素及其体内主要代谢产物4-差向土霉素、α-阿扑土霉素、β-阿扑土霉素和2-乙酞-2-...     

土霉素在奥尼罗非鱼体内的药动学研究

在(21±1)℃的水温条件下,以50 mg/kg的单剂量,分别给奥尼罗非鱼(Oreochromis aureus×O.niloticus)水剂口灌和混饲口灌土霉素,用高效液相色谱法(HPLC)检测给药后各个时间点的血药浓度。结果显示:最低检测限为0.005μg/mL,线性范围为0.005~4μg/mL。水剂口灌组和混饲口灌组的药时数据均符合具时滞的二室开放动力学模型,水剂口灌组的动力学方程为:Ct=0.231e-0.028(t-0.010)+0.353e-0.011(t-0.010)-0.584e-0.468(t-0.010),混饲口灌组动力学方程:Ct=0.839e-0.057(t-0.459)+0.442e-0.013(t-0.459)-1.281e-0.282(t-0.459)。水剂口灌组及混饲口灌组主要药动学参数分别为:吸收半衰期(t1/2ka)为1.481 h,2.458 h;分布半衰期(t1/2α)为24.834 h,12.193 h;消除半衰期(t1/2β)为60.312 h,51.533 h;达峰时间(Tmax)为7.230 h,8.221 h;最大血药浓度(Cmax)为0.494μg/mL,0.796μg/mL;血药浓度-时间曲线下面积(AUC)=37.74μg.h/mL,43.075μg.h/mL。这些参数表明,水剂口灌比混饲口灌吸收快,分布和消除慢,在血液中达到峰浓度的时间更短,但峰浓度值比混饲口灌低。     

四环素类抗菌药物在吉富罗非鱼体内的代谢动力学研究

给吉富罗非鱼一次灌服50mg/kg剂量的四环素和土霉素浑浊液,研究四环素和土霉素在其肌肉、肝脏和血液中的残留与消除规律。12h后四环素、土霉素在肌肉、肝脏和血液中含量分别达最高,四环素含量分别为0.920mg/kg,2 703mg/kg,1 225μg/mL;土霉素含量分别为0 860,2 188mg/kg和1 075μg/mL。鱼肉中四环素的分布半衰期和消除半衰期分别为8 593,23 50h;土霉素的分布半衰期和消除半衰期分别为8 261,22 979h。216h后,鱼肉中四环素和土霉素均低于0 1mg/kg。