Vitamin A deficiency and hepatic retinol levels in sea otters, Enhydra lutris

Vitamin A deficiency has rarely been reported in captive or free-ranging wildlife species. Necropsy findings in two captively housed southern sea otters (Enhydra lutris nereis) included irregular thickening of the calvaria characterized by diffuse hyperostoses on the internal surface. One animal also had moderate squamous metaplasia of the seromucinous glands of the nose. There was no measurable retinol in the liver of either sea otter. For comparison, hepatic retinol concentration was determined for 23 deceased free-ranging southern and northern (Enhydra lutris kenyoni) sea otters from California and Alaska. Free-ranging otters were found to have similar hepatic retinol concentrations (316 +/- 245 mg/kg wet weight) regardless of their location and subspecies. All of these values were significantly higher than the levels in the affected animals. Consumption of a diet with very low vitamin A concentrations and noncompliance in daily supplementation are hypothesized as the causes of vitamin A deficiency in these two sea otters.     

林业发展所面临的形势及国民经济发展对林业的需求分析

文章着重分析了内蒙古当前林业发展形势及国民经济发展对林业的需求 ,并客观的论述了自治区林业发展的有利条件和制约因素 ,希望能够对今后的林业建设有所帮助 ,从而把握机遇 ,加快环境建设步伐 ,早日改善环境状况。     

Angular distribution of radiation beneath forest canopies using a CCD-radiometer

An astronomical digital camera is equipped with a fish-eye lens and exchangeable filters to study the fine angular structure of radiation field in forests in the red and near infrared (NIR) spectral bands. A few examples of the angular distribution of downward radiances in conifer and broadleaf forests are given. The results of field measurements are compared with the spectral flux measurements by a field radiometer and with the calculations of radiance by a combined geometric-optical/radiative transfer (RT) model. The test measurements demonstrated that the hemispheric-view imaging radiometer is a good tool to validate canopy RT models.     

Influence of Inseminate Components on Porcine Leucocyte Migration In Vitro and In Vivo after Pre- and Post-Ovulatory Insemination

A post‐breeding migration of leucocytes (PMN) into the uterus is considered to be an important reason for sperm losses. Minimizing such effects may be necessary for successful insemination with low sperm numbers, as required with sex‐sorted spermatozoa. We examined the magnitude of PMN influx 3 h after pre‐ or post‐ovulatory insemination with various combinations of seminal plasma (SP), semen extender Androhep? (AH; Minitüb, Tiefenbach, Germany) and sperm preparations (S). Pre‐ovulatory inseminations with preparations containing 98% AH caused a massive influx of PMN, independent of whether spermatozoa were present (628 ± 189 × 10⁶ leucocytes/uterine horn) or not (580 ± 153 × 10⁶). Post‐ovulatory, 98% AH caused a comparable immigration only in the absence of sperm cells (AH: 569 ± 198 × 10⁶, AH+S: 162 ± 102 × 10⁶). The presence of SP significantly dampened the numbers of recruited uterine leucocytes. The reaction to all inseminates containing 98% SP both with and without spermatozoa, used before ovulation (SP: 14 ± 6 × 10⁶, SP+S: 73 ± 27 × 10⁶) and after ovulation (SP: 60 ± 32 × 10⁶, SP+S: 51 ± 33 × 10⁶) did not differ significantly from controls using phosphate buffered saline (PBS) (pre‐ovulatory: 1 ± 1 × 10⁶, post‐ovulatory: 11 ± 9 × 10⁶). Quantitative in vitro transmigration assays with blood‐derived PMN proved that AH‐induced leucocyte migration into the uterus to be not as a result of direct chemotaxis, because, on account of the chelator citrate, AH significantly inhibited the transmigration towards recombinant human Interleukin‐8 (rhCXCL8) (AH: 14 ± 5% migration rate vs controls: 37 ± 6%, p < 0.05). Supernatants of spermatozoa incubated in PBS for 1, 12 or 24 h showed neither chemoattractive nor chemotaxis‐inhibiting properties. SP at ≥0.1% [v/v] significantly inhibited the in vitro transmigration of PMN. With respect to in vivo migration of neutrophils, the striking difference in the results between semen extender and seminal plasma suggests that adaptation of extender composition is needed to reflect more closely the in vivo regulatory potential of natural seminal plasma.     

Hatching and rearing lobster larvae (Homarus americanus) in a disease situation

Lobster rearing facilities in the United States suffered severe losses of larval stages during the summer of 1974 hatching season. The organisms responsible for losses at the Bodega Marine Laboratory were the fungus Lagenidium sp. and epiphytic contaminants. Various systems and treatments were used in attempts to overcome the problems encountered. Postlarval lobsters were produced successfully in a semi-closed system using ultraviolet-irradiated sea water and a malachite green dip for eggs and larvae.     

Selection of new sweet potato genotypes based on production parameters,physical root characteristics and resistance to Euscepes postfasciatus

Journal of Crop Science and Biotechnology - Sweet potato (Ipomoea batatas L.) is a root that allows healthy eating and combats malnutrition. There is a need for more productive sweet potato...     

Simulation of statistical characteristics of gap distribution in forest stands

An estimate of the required amount of LAI-2000 or digital hemispheric image measurements to ensure the desired accuracy of the leaf area index value derived from optical analyser measurements by inversion of gap fraction data is given. The estimate is based on a theoretical model of the second order statistics of gap occurrence in forest canopies. The main attention is paid to gap fractions averaged over the angular rings similar to the LAI-2000 instrument. Nilson's (1999) forest gap fraction model is first extended to simulate the bidirectional gap fraction and next the approximate equations for the standard deviation of gap fraction, correlation matrix of gap readings in different LAI-2000 angular rings, standard deviation of the LAI value as determined by the inversion of gap fraction data are derived. The results of simulation are compared with those obtained by LAI-2000 instrument and digital hemispheric photographs in three mature forests from Järvselja, Estonia. The comparison shows an acceptable agreement between the simulated and measured second order statistical characteristics. The distance from the observation height to the crowns and crown dimensions appear to be important in determining the magnitude of variance. When the LAI-2000 instrument is used together with a view-cap, the angular size of the view-cap has an effect on the second order statistics and on the value of apparent clumping index. A computer program has been written to calculate the second-order gap statistics.     

两种饲喂方式对哺乳母猪生产性能的影响研究

选取年龄、胎次、品种基本一致的哺乳母猪20头,随机分成对照组和试验组,试验分两批进行,每批10头。在相同的环境条件下,母猪自由饮水,饲喂同一哺乳母猪料。母猪分娩后4d内,采用原场饲养制度,逐步增加哺乳母猪采食量,第5天开始,对照组采用不限量饲喂,试验组采用限量和添加哺乳母猪补充料的饲喂方式,仔猪21日龄断奶。结果显示:两组仔猪21日龄的断奶窝重、母猪断奶后再发情时间和母猪哺乳失重等差异均不显著(P>0.05)。     

人兽共患病原菌－猪链球菌2型的发病特点与防治对策

猪链球菌病是我国规定的二类动物传染病，其2型菌对人和猪均有很强的致病性，对公共卫生安全构成威胁。结合国内外10多年来对猪链球菌2型的病原特点、流行病学、临床症状和毒力因子的相关研究情况，总结了猪链球菌2型的发病特点，提出了针对该病的防治对策，为有效预防和控制人兽共患病的发生提供参考意见。