不同声音对草鱼幼鱼负趋音性行为反应影响研究

声驱鱼技术作为辅助过鱼措施之一,承担着保证鱼类洄游顺利通过过鱼设施,继而保护鱼类资源和恢复河流连通性的重要作用。本研究采用交替播音的形式,以草鱼(Ctenopharyngodon idellus)幼鱼为研究对象进行负趋音性实验,旨在探究草鱼幼鱼面对不同声音的行为反应。实验水槽(3.6 m×1.1 m×1.0 m)布置于下牢溪周围水域,平均水深为0.5 m,平均流速为0.06 m/s。实验使用1种单频音(1 000 Hz)和5种复杂音(鱼游动声、引擎声、短吻鳄叫声、打桩声和游艇声),声压级(sound pressure level)为(117.69±2.77) dB re 1 μPa,对照组为未播放声音时草鱼的行为反应数据。结果显示,播放复杂音时,草鱼的反应次数、趋音速度、运动时间比均显著高于单频音和对照组(P<0.001),草鱼的初次反应时间、平均反应时间均显著低于单频音和对照组(P<0.001);复杂音中,受到游艇声刺激的草鱼反应次数和趋音速度最大,受到鱼游动声刺激的草鱼反应次数、趋音速度最小;复杂音中,受到游艇声刺激的草鱼初次反应时间最短,为(23.40±5.13) s;受到引擎声刺激的草鱼初次反应时间最长,为(146.00±7.82) s,显著低于其他复杂音(P<0.05);受到游艇声和打桩声刺激的草鱼平均反应时间最短,分别为(26.52±3.01) s和(28.76±4.07) s;受到鱼游动声刺激的草鱼平均反应时间最长,为(64.76±17.82) s;复杂音中,受到鱼游动声刺激的草鱼运动时间比最高,为(98.47±0.48)%;受到引擎声刺激的草鱼运动时间比最低,为(94.58±0.54)%;播放单频音时,草鱼的反应次数、初次反应时间、平均反应时间、运动时间比均与对照组无显著差异(P>0.05)。本研究表明,5种复杂音(鱼游动声、引擎声、短吻鳄叫声、打桩声和游艇声)对草鱼幼鱼具有驱赶效果。本研究在丰富鱼类负趋音性研究的同时,为实际工程中声驱鱼辅助过鱼设施的设计和优化提供了科学依据。     

THE EFFECT OF HISTAMINE ON SILAGE DRY-MATTER INTAKE

The oral introduction of 0·5 g histamine as the diphosphate into the rumen of sheep produced no effect on the physiological condition of the animals. The feeding of histamine, as the dihydrochloride, in levels up to 1 g/day to sheep on silage diets did not affect the dry-matter intake.     

不同干豆豆浆机制备豆浆的主要品质评价

以大豆为原料选用我国2个主导品牌的3款豆浆机(九阳精磨豆浆机、九阳无网干豆豆浆机、美的无网干豆豆浆机)制作豆浆,从蛋白质含量、蛋白质回收率、豆浆颗粒度及感官特性等方面对豆浆品质进行评价.结果表明:豆浆的蛋白含量为1.72%～2.66%,蛋白回收率为47.13%～68.66%,带有精磨器的豆浆机制备的豆浆蛋白含量及蛋白回...     

Relationships between soil and foliar nutrients in young densely planted mini-plots of Pinus radiata and Cupressus lusitanica

The long-term nature of forest crop rotations makes it difficult to determine impacts of forestry on soil nutrients that might be depleted by forest growth. We used small scale, highly stocked plots to compress the length of the rotation and rapidly induce nutrient depletion. In the study, two species (Pinus radiata D. Don and Cupressus lusitanica Miller) are compared under two disturbance regimes (soil undisturbed and compacted), and two fertiliser treatments (nil and plus fertiliser), applied in factorial combination at 33 sites, covering the range of climatic and edaphic variation found in plantation forests across New Zealand. To assess our ability to rapidly highlight important soil properties, foliar nutrient concentrations were determined 20 months after planting. It was hypothesised that the densely planted plots, even at a young age, would create sufficient pressure on nutrient resources to allow development of relationships between properties used as indicies of soil nutrient availability and foliar nutrient concentrations. For both species significant relationships between foliar nutrients and 0–10 cm layer soil properties from unfertilised plots were evident for N (total and mineralisable N) and P (total, acid extractable, organic, Bray-2 and Olsen P). With the exception of Ca in C. lusitanica, foliar K, Ca and Mg were correlated with their respective soil exchangeable cation measures. The results thus confirm the utility of the experimental approach and the relevance of the measured soil properties for forest productivity.

In unfertilised plots foliar N and P concentrations in P. radiata exceeded those in C. lusitanica, the differences being eliminated by fertiliser application. Foliar N/P ratios in P. radiata also exceeded those in C. lusitanica. In contrast to N and P, foliar K, Ca and Mg concentrations were all higher in C. lusitanica, the difference being particularly marked for Ca and Mg. P. radiata contained substantially higher concentrations of the metals Zn, Mn and Al than C. lusitanica, whereas the latter contained higher B concentrations. Possible reasons for differences between species in foliar nutrient concentrations are discussed.     

Approaches to pathogen-mediated resistance breeding against plum pox potyvirus in stone-fruit trees1

In a programme for developing systems which allow the transfer of foreign genes into apricot cultivars, we have tested cotyledons of immature embryos, somatic embryos and leaf discs. Apricot plants have been transformed, and then regenerated, with Agrobacterium tumefaciens strain LBA 4404 containing various binary plasmids: pBinGUSint, carrying the marker gene β-glucuronidase (GUS), and pBinPPVm, carrying the coat-protein gene of plum pox potyvirus (PPV). The marker gene GUS was used for visual evaluation of the efficiency of the transformation system. The coat-protein gene was used in the hope of introducing coat protein-mediated resistance to one of the most important stone-fruit pathogens in Europe and the Mediterranean area.     

Arthrodesis of the equine proximal interphalangeal joint: a biomechanical comparison of three 4.5-mm and two 5.5-mm cortical screws

OBJECTIVE--To compare the biomechanical characteristics and mode of failure of 2 parallel-screw techniques for proximal interphalangeal joint arthrodesis in horses. STUDY DESIGN--Randomized block design, blocking for horse (1-5), method of screw fixation (three 4.5-mm vs two 5.5-mm), side (left limb vs right limb), and end (front limb vs hind limb). Constructs were loaded to failure in 3-point bending in a dorsal-to-palmar (plantar) direction. SAMPLE POPULATION--Twenty limbs (10 limb pairs) from 5 equine cadavers. METHODS--A combined aiming device was used to facilitate consistent screw placement. Three parallel 4.5-mm cortical screws were placed in lag fashion in 1 limb of a pair, and 2 parallel 5.5-mm cortical screws were placed in lag fashion in the contralateral limb. Arthrodesis constructs were tested in 3-point bending in a dorsal-to-palmar (plantar) direction using a materials-testing machine. Loading rate was 19 mm/s. Maximal bending moment at failure and composite stiffness were obtained from bending moment-angular deformation curves. Data were analyzed using ANOVA and chi(2) analysis. RESULTS--There were no significant differences in bending moment (P >.05, power = 0.8 @ delta = 19%) or composite stiffness (P >.05, power = 0.8 @ delta = 19%) between the 2 fixation techniques. Higher maximal bending moment was found in front limbs than hind limbs, and front limbs with two 5.5-mm screws than hind limbs with two 5.5-mm screws. In all cases, constructs completely failed. A greater number of 4.5-mm cortical screws failed than 5.5-mm cortical screws. CONCLUSIONS-In pastern arthrodesis constructs loaded in 3-point bending, end (front limb vs hind limb) affected maximal bending moment at failure of constructs. There was no significant effect of horse, treatment, or side on maximal bending moment or stiffness. Two 5.5-mm cortical screws should provide a surgically simpler pastern arthrodesis than three 4.5-mm cortical screws while maintaining similar biomechanical characteristics. CLINICAL RELEVANCE--Three 4.5-mm screws or two 5.5-mm screws will provide similar biomechanical characteristics in bending when performing equine pastern arthrodesis.     

Prevalence of caseous lymphadenitis and usage of caseous lymphadenitis vaccines in sheep flocks

OBJECTIVE: To estimate the prevalence of caseous lymphadenitis (CLA), determine the current usage of vaccines against CLA and to measure the effectiveness of these vaccines on sheep farms. DESIGN AND POPULATION: A survey was undertaken on 223 sheep flocks in New South Wales, Victoria and Western Australia. METHOD: The prevalence of CLA was measured by conventional inspection techniques at abattoirs in lines of sheep that could be traced back to a farm. Managers of the flocks were sent a questionnaire about their vaccine practices, management practices and knowledge of CLA. RESULTS: The average prevalence of CLA in adult sheep in these flocks was 26% and varied from 20% in Western Australia to 29% in New South Wales. About 43% of sheep producers used CLA vaccines; only 12% used them as recommended. Awareness of CLA was highest in Western Australia. More producers would use CLA vaccine if they knew the prevalence of CLA in their flock and producers obtained most information about CLA from vaccine resellers. CONCLUSIONS: Only 10 to 15% of producers are currently achieving effective CLA control through the use of recommended CLA vaccination programs. In Western Australian flocks more than 25% of effectively vaccinated ewes will be sent to abattoirs in the 2 to 3 years after this study. However, large decreases in the prevalence of CLA can be achieved by about 70% of producers by either making adjustments to their vaccination programs or buying a vaccine with a CLA component. Two or three key facts on effective CLA vaccination could be made available at the point of sale of vaccines and from abattoirs that reported the prevalence of CLA to farmers.