主要养殖鲟鱼的生物学及养殖前景   总被引：10，自引：0，他引：10  

卢迈新  黄樟翰  肖学铮  吴锐全 《大连水产学院学报》2000,15(4):280-287

鲟鱼是世界上最古老的鱼类之一,现存鲟鱼种数有２５～２６种。由于多年的酷渔滥捕和生态环境恶化,鲟鱼资源日益衰退。１９９０年世界鲟鱼产量为２万ｙ,１９９３年下降到１万ｔ。本文作者综述了鲟鱼类的起源、地理分布、生态习性和生物学特性,分析和讨论了开展鲟鱼养殖应注意的问题及鲟鱼的养殖前景。  相似文献   

京西山地棕壤和淋溶褐土饱和导水率的分析   总被引：13，自引：0，他引：13  

马履一  翟明普  王勇 《林业科学》1999,35(3):109-112

导水率Ｋ（ｈｙｄｒａｕｌｉｃｃｏｎｄｕｃｔｉｖｉｔｙ）是表示孔隙介质透水性能的综合比例系数,即单位水力势梯度下水的通量密度或渗透流速。Ｋ值是土壤颗粒大小分布、固体物质的化学组成和土壤紧实度的函数。因此,对于不同的土壤或同一土壤的不同层次Ｋ值亦可能有差...  相似文献   

三亚市10年间景观格局变化分析          下载免费PDF全文

林宁  关学彬  麦全法 《农学学报》2017,7(2):68-73

为了充分了解热带滨海城市发展过程中景观变化特征及其影响因素,利用基于SPOT的影像数据,应用RS、GIS 软件和景观生态学方法,以海南省三亚市作为研究对象,分析了2002—2012 年三亚市土地利用及景观格局的动态变化情况。结果表明：（1）三亚市仍以耕地和阔叶林为主,建设用地大幅度增加,各土地利用类型有相互转移表现,2002—2012 年,水田面积减少了25.75%,水库/坑塘减少6.21%;草丛、建设用地和旱地面积分别增加143.16%、86.89%和10.20%;（2）运用景观格局指数和转移矩阵分析,得出研究区域景观斑块总体数量减少,说明这期间三亚景观破碎化趋势降低,主要由于人类活动的干扰不断加强,城市化进程加快使原来分散的乡镇村落等居民集中地聚集成片,转变为城市化建筑群,从而导致了研究区域景观破碎化程度的下降。  相似文献   

Molecular cloning and characterization of taurine transporter from turbot (Psetta maxima) and its expression analysis regulated by taurine in vitro          下载免费PDF全文

Xuan Wang  Gen He  Kangsen Mai  Wei Xu  Huihui Zhou 《Aquaculture Research》2017,48(4):1724-1734

  相似文献   

Replacement of fish meal by meat and bone meal in diets for large yellow croaker, Pseudosciaena crocea     

Qinghui Ai  Kangsen Mai  Beiping Tan  Wei Xu  Qingyuan Duan  Hongming Ma  Lu Zhang 《Aquaculture (Amsterdam, Netherlands)》2006,260(1-4):255-263

A growth experiment was conducted to investigate the effects of replacement of fish meal (FM) by meat and bone meal (MBM) in diets on the growth and body composition of large yellow croaker (Pseudosciaena crocea). Six isonitrogenous (43% crude protein) and isoenergetic (20 kJ g^− 1) diets replacing 0, 15, 30, 45, 60 and 75% FM protein by MBM protein were formulated. Each diet was randomly allocated to triplicate groups of fish in sea floating cages (1.0 × 1.0 × 1.5 m), and each cage was stocked with 180 fish (initial average weight of 1.88 ± 0.02 g). Fish were fed twice daily (05:00 and 17:30) to apparent satiation for 8 weeks. The water temperature ranged from 26.5 to 32.5 °C, salinity from 32 to 36‰, and dissolved oxygen content was approximately 7 mg l^− 1 during the experimental period. Survival decreased with increasing dietary MBM and the survival in the fish fed the diet with 75% protein from MBM was significantly lower than other groups (P < 0.05). There were no significant differences in specific growth rate (SGR) among the fish fed the diets with 0 (the control group), 15, 30 and 45% protein from MBM. However, SGR in the fish fed the diets with 60 and 75% protein from MBM were significantly lower than other groups (P < 0.05). No significant differences in feeding rate were observed among dietary treatments. The digestibility experiment showed that the apparent digestibility coefficients (ADC) of dry matter, protein, lipid and energy of MBM were significantly lower compared with those of FM (P < 0.05). Essential amino acid index was found to be correlated positively with SGR in the present study, suggesting that essential amino acid balance was important. Body composition analysis showed that the carcass protein and essential amino acids were not significantly affected by dietary MBM. The lipid and n-3 highly unsaturated fatty acid (n-3 HUFA) in fish muscle, however, significantly decreased with increasing dietary MBM. These results showed that 45% of FM protein could be replaced by MBM protein in diets of large yellow croaker without significantly reducing growth. It was suggested that the reduced growth with higher MBM was due to lower digestibility and imbalance of essential amino acids.  相似文献   

Detection of Oestrus in Bunaji Cows under Field Conditions     

Mai HM  Ogwu D  Eduvie LO  Voh AA 《Tropical animal health and production》2002,34(1):35-47

The objective of this study was to determine the efficacy of some aids for detectiong oestrus in 72 Bunaji cows synchronized using two injections of prostaglandin F₂ (PGF₂) 13 days apart. Blood samples to determine the accuracy of the aids and ovarian activity by radioimmunoassay technique were collected daily from the day of the second PGF₂ injection until oestrus or for 168 hours for `non-responders'. The aids for detecting oestrus, tail painting, KaMar detectors and a chin-ball mating device (CMD) were applied at the time of the second injection.The oestrus response rate was 73.6% and 61.1%, from the serum progesterone concentration and visual observation, respectively. Based on the total number of oestrus events observed, unaided visual observation, tail painting, KaMar and CMD detected 52.2%, 82.6%, 82.6% and 76.8%, respectively. Visual observation of standing oestrus alone failed to detect 47.8% of the occurrence of oestrus as shown by the concentration of progesterone in the serum and 30.4%, 30.4% and 24.6%, respectively, of the oestrus periods recorded by tail painting, KaMar and CMD. Twenty-eight cows showed abnormalities in progesterone concentration.These investigations showed that oestrus may be detected by using the aids in cows that have been regarded as `anoestrous' by visual observation of standing heat.  相似文献   

金钱豹消化试验     

黎绘宏  李婉萍  黄志宏  王兴金  张盈盈  原浩华  任浩斌  麦宴威 《野生动物》2006,27(6):32-34

为探讨金钱豹对含植物性成分的混合日粮的消化情况,采用市售某品牌罐装犬粮(简称罐头组)饲喂7只金钱豹,测定其主要营养成分的表观消化率,同时设牛肉和瘦猪肉组成的纯肉日粮(简称纯肉组)作为对照。结果表明,纯肉组干物质、粗蛋白、脂肪、能量等主要营养成分的表观消化率分别为：(97．37±0．69)％、(98 98±0．32)％、(97．78±0．47)％、(98．30±0 43)％,罐头组干物质、粗蛋白、脂肪、能量等主要营养成分的表观消化率分别为：(74．49±4．18)％、(85．74±1．50)％、(90．45±5．02)％、(94．92±3．27)％。其中干物质和蛋白质的表观消化率组问呈极显著差异(P＜0．01),脂肪的表观消化率组间达显著差异(P＜0．05),而能量的表观消化率组间差异不显著(P＞0．05)。  相似文献   

Superficial digital flexor tendonitis in Thoroughbred race horses: outcome following non-surgical treatment and superior check desmotomy     

KT GIBSON  HM BURBIDGE  DU PFEIFFER 《Australian veterinary journal》1997,75(9):631-635

Objective This study documents the results of non-surgical treatment and treatment by superior check desmotomy in Thoroughbred racehorses with superficial digital flexor (SDF) tendonitis. Design A prospective study was made of 124 thoroughbred racehorses with unilateral or bilateral SDF tendonitis. Procedure The flexor tendons were assessed by physical and ultrasonographic examination before treatment, and the lesions detected in affected tendons were characterised according to lesion type, length and cross-sectional area. Ninety three horses were managed non-surgically and 31 by superior check desmotomy. Recurrent or new injuries were defined as injuries affecting a previously injured superficial digital flexor tendon, the contralateral SDF tendon, or the suspensory ligament (interosseous muscle) in either forelimb. Results No statistically significant difference was found in ultrasonographic lesion severity between treatment groups. Horses managed by superior check desmotomy were 1.3 times more likely to complete five or more races than horses managed non-surgically (95% confidence limits 0.93–1.82). Horses treated surgically were 1.2 times more likely to develop recurrent or new injuries after returning to training than horses managed non-surgically (95% CL 0.95–1.55). Horses under-going superior check desmotomy were 5.5 times more likely to develop suspensory desmitis than horses treated non-surgically (95% CL 1.13–26.4). There was no difference in the time to recurrent or new injury between treatment groups. Conclusion There was no statistically significant difference between treatment groups in the proportions of horses able to complete five or more races after an episode of superficial digital flexor tendonitis. Superior check desmotomy did not appear to offer an advantage over non-surgical treatment in preventing recurrent or new injuries in Thoroughbred racehorses. Horses undergoing superior check desmotomy appeared to be at greater risk of developing suspensery ligament injuries than horses managed non-surgically.  相似文献   

ASSOCIATIONS BETWEEN ULTRASOUND AND CLINICAL FINDINGS IN 87 CATS WITH URETHRAL OBSTRUCTION          下载免费PDF全文

Jonathan R. Nevins  Wilfried Mai  Emily Thomas 《Veterinary radiology & ultrasound》2015,56(4):439-447

Urethral obstruction is a life‐threatening form of feline lower urinary tract disease. Ultrasonographic risk factors for reobstruction have not been previously reported. Purposes of this retrospective cross‐sectional study were to describe urinary tract ultrasound findings in cats following acute urethral obstruction and determine whether ultrasound findings were associated with reobstruction. Inclusion criteria were a physical examination and history consistent with urethral obstruction, an abdominal ultrasound including a full evaluation of the urinary system within 24 h of hospitalization, and no cystocentesis prior to ultrasound examination. Medical records for included cats were reviewed and presence of azotemia, hyperkalemia, positive urine culture, and duration of hospitalization were recorded. For medically treated cats with available outcome data, presence of reobstruction was also recorded. Ultrasound images were reviewed and urinary tract characteristics were recorded. A total of 87 cats met inclusion criteria. Common ultrasound findings for the bladder included echogenic urine sediment, bladder wall thickening, pericystic effusion, hyperechoic pericystic fat, and increased urinary echoes; and for the kidneys/ureters included pyelectasia, renomegaly, perirenal effusion, hyperechoic perirenal fat, and ureteral dilation. Six‐month postdischarge outcomes were available for 61 medically treated cats and 21 of these cats had reobstruction. No findings were associated with an increased risk of reobstruction. Ultrasonographic perirenal effusion was associated with severe hyperkalemia (P = 0.009, relative risk 5.75, 95% confidence interval [1.54–21.51]). Findings supported the use of ultrasound as an adjunct for treatment planning in cats presented with urethral obstruction but not as a method for predicting risk of reobstruction.  相似文献   

散体物料孔隙率测定装置设计与试验     

李长友  方壮东  麦智炜 《农业机械学报》2014,45(10):200-206

为了提高散体物料孔隙率检测精度及可靠性,基于理想气体状态方程,按照气体置换法,研制了一种定容型散体物料孔隙率的快速测定装置,开发了自动检测控制系统。在设定的0.1~0.4 MPa测量范围内,采用可精确测得其体积且形态各异的标准不锈钢球体、塑料四棱柱体、鹅卵石以及细石子的试验结果发现,系统的充气压力越高,测量误差相对越小且重复性越好。采用标准不锈钢球体与圆柱体,在孔隙率分别为16.02%、25.14%、35.57%、49.05%、58.42%、67.79%、76.57%、85.36%、94.14%的标准条件下,给出了补偿系数的计算式。在样品填充率分别为25%、50%、75%、100%,充气上限压力为0.4 MPa的试验条件下,检测湿基含水率为13.5%的稻谷的试验结果显示,测量误差极差为0.3%,证实了测量结果的可靠性。  相似文献