Studies on the Motility and Cryopreservation of Rainbow Trout (Salmo Gairdneri) Spermatozoa

The very short duration of vigorous movement (1 1/2 to 7 min) in fresh water and physiological solutions make trout spermatozoa difficult subjects for cryopreservation studies. Solutions consisting of 250 to 280 mmol sucrose and 5 to 12% dimethyl sulphoxide (DMSO) (4 parts) did not activate trout spermatozoa (1 part), but after dilution with fresh water vigorous motility could be fully restored. These sucrose-DMSO solutions were employed in cryopreservation studies. Using straws and a fast freezing — fast thawing procedure, post-thaw dilution with fresh water resulted in 25%-60% of spermatozoa becoming motile, all with vigorous forward progression. Some existing methods for the cryopreservation of other freshwater fish spermatozoa were repeated on trout without success.     

Implementing Sustainable Forest Management Using Six Concepts in an Adaptive Management Framework

Certification and principles, criteria and indicators (PCI) describe desired ends for sustainable forest management (SFM) but do not address potential means to achieve those ends. As a result, forest owners and managers participating in certification and employing PCI as tools to achieving SFM may be doing so inefficiently: achieving results by trial-and-error rather than by targeted management practices; dispersing resources away from priority objectives; and passively monitoring outcomes rather than actively establishing quantitative goals. In this literature review, we propose six concepts to guide SFM implementation. These concepts include: Best Management Practices (BMPs)/Reduced Impact Logging (RIL), biodiversity conservation, forest protection, multi-scale planning, participatory forestry, and sustained forest production. We place these concepts within an iterative decision-making framework of planning, implementation, and assessment, and provide brief definitions of and practices delimited by each concept. A case study describing SFM in the neo-tropics illustrates a potential application of our six concepts. Overall our paper offers an approach that will help forest owners and managers implement the ambiguous SFM concept.     

An Exploratory,Post-Harvest Comparison of Ecological and Economic Characteristics of Forest Stewardship Council Certified and Uncertified Northern Hardwood Stands∗

ABSTRACT

As more forest entities worldwide consider pursuing Forest Stewardship Council (FSC) certification, a critical question remains on whether stand-level management impacts differ between certified and uncertified forests. To begin to answer this question, we measured forest structure on three FSC-certified stands, three uncertified stands, and six adjacent unharvested reference stands (12 stands total) composed primarily of sugar maple (Acer saccharum) on non-industrial private properties in central Vermont, USA. The certified and uncertified partial harvests reduced total tree biomass and live tree carbon storage by one-third compared to reconstructed pre-harvest conditions. Both treatments also contained significantly lower densities of saplings and some mid-size trees compared to non-harvested references due to similar impacts from harvesting. The net present value of merchantable sugar maple over 10 year projections was consistently lower on certified than uncertified stands, but this difference was insignificant at discount rates from 4–8%. The certified stands contained significantly greater total residual volumes of coarse woody debris (standing and downed) than uncertified stands, although the debris was smaller than that found in unmanaged mature forests. Overall, our data suggest that FSC-certified harvested stands in northern hardwood forests have similar sugar maple timber value, aboveground live tree carbon storage value, similar live tree structure, and greater residual coarse woody debris than uncertified harvested stands.     

Role of genetically engineered animals in future food production

Genetically engineered (GE) animals are likely to have an important role in the future in meeting the food demand of a burgeoning global population. There have already been many notable achievements using this technology in livestock, poultry and aquatic species. In particular, the use of RNA interference (RNAi) to produce virus‐resistant animals is a rapidly‐developing area of research. However, despite the promise of this technology, very few GE animals have been commercialised. This review aims to provide information so that veterinarians and animal health scientists are better able to participate in the debate on GE animals.     

Conception rates to fixed-time artificial insemination of two oestrus synchronisation programmes in dairy heifers

AIM: To evaluate the conception rate to fixed-time artificial insemination (FTAI) of two oestrus synchronisation programmes in dairy heifers on eight farms over 2 years.

METHODS: The study was conducted in 2008 and 2010 on eight farms near Palmerston North, New Zealand. Nulliparous Friesian and Friesian×Jersey heifers (13–15 months of age) were randomly allocated to one of two oestrus synchronisation programmes. Group 1 (GPG+P4; n=330), received gonadotrophin-releasing hormone (GnRH) I/M on Day 0, a progesterone (P4)-releasing intravaginal device from Days 0–7, prostaglandin F_2α (PGF) I/M on Day 7 and a second dose of GnRH at the time of FTAI on Day 9. The second group (P4+PGF; n=343) received a P4-releasing intravaginal device from Days 0–7, PGF on Day 6 and FTAI on Day 9. Pregnancy was diagnosed from Days 42–52 by transrectal ultrasonography.

RESULTS: The overall conception rate was 52.4% and 54.8% for the GPG+P4 and P4+PGF groups, respectively. The odds of conception for the two treatments were not different (OR=0.90; 95% CI=0.67–1.23), nor was there any difference between groups in different years (p=0.58). Farm affected conception rate (p=0.002), but there was no interaction with treatment (p=0.92) .

CONCLUSIONS: This study has shown that an alternative synchronisation programme can produce similar results in terms of conception rate to the GPG+P4 treatment, currently commonly used in heifers. More research is required to establish whether other modifications to the GPG+P4 programme can produce similar results at lower costs, and to identify and quantify farm factors which affect the economic benefit of heifer synchronisation.

CLINICAL RELEVANCE: This study indicated that synchronising heifers with P4 and PGF resulted in conception rates equivalent to those resulting from a GPG+P4 treatment, but with reduced drug costs. However, because heifers in the GPG+P4 group received the second GnRH injection at the time of AI, they needed only three yardings as opposed to the four required for the heifers treated with P4 and PGF. Thus, the choice of programme for an individual farm will depend on that farm's circumstances, in particular the cost of yarding the heifers.     

Culture results from milk samples submitted to veterinary diagnostic laboratories from August 2003 to December 2006 in New Zealand

Abstract

AIMS: To determine the pattern of isolation of major mastitis-causing organisms isolated from milk samples submitted to five veterinary diagnostic laboratories in New Zealand.

METHODS: The culture results of 25,288 milk samples that were collected from dairy cows throughout New Zealand from August 2003 to December 2006 and submitted to a group of veterinary diagnostic laboratories were assembled, reviewed and summarised. Logistic regression was used to analyse the effect of year, region (i.e. North vs South Island), and season on the probability of isolating the two most common organisms.

RESULTS: The most commonly isolated mastitis causing organisms from all samples were: Streptococcus uberis (23.6%), Staphylococcus aureus (23.5%), coagulase-negative staphylococci (CNS; 7.2%), Strep. dysgalactiae (6.2%), Bacillus spp. (4.0%), and coliforms (3.7%). The percentage of samples with isolates of Strep. uberis or Staph. aureus was affected by island, year and season (p<0.001). For most of the year, except in late winter and early spring when Strep. uberis was much more common, the percentage of isolates of Strep. uberis and Staph. aureus were not apparently different despite the former being an environmental pathogen and the other a contagious one.

CONCLUSION: The pattern of isolation of major mastitis-causing organisms, as determined from culture of milk samples submitted to diagnostic laboratories in New Zealand, has changed significantly over the last 40 years, with a substantial increase in the percentage of isolates that are Strep. uberis and a decrease in isolates of Strep. agalactiae. There is a clear seasonal pattern to the isolation of both Strep. uberis and Staph. aureus, particularly the former.

CLINICAL RELEVANCE: Knowledge of the aetiological agents causing bovine mastitis on a farm is of value in determining the choice of treatment. This dataset shows that, although there is seasonal pattern to the isolation of mastitis-causing organisms in New Zealand, both Strep. uberis and Staph. aureus are isolated throughout the year, so bacteriology is of value in determining aetiology even in late winter/early spring.     

GU-PCM2型控温式相变蓄冷冷藏车设计与空载性能试验

现有蓄冷冷藏车蓄冷装置多位于车厢顶部,存在重心偏高、不可控温等问题,基于此,该文设计了一款集相变蓄冷单元、车载制冷系统、隔热车厢、送风系统等于一体的GU-PCM2型蓄冷冷藏车。该蓄冷车将蓄冷装置独立设置于车厢前端并保温,系统利用夜间低谷电进行充冷,可在-25～10℃之间根据需要调控车厢温度。对蓄冷冷藏车厢设定温度为0和-18℃的2种工况进行空载温度场仿真与测试。结果表明,车厢内各测温点的模拟温度与实测温度均方根误差分别为0.7和0.8℃,最大绝对误差分别为1.1和1.2℃。冷藏车可有效控温10 h以上,车厢平均温度分别在1.1～2.9℃和-14.8～-16.9℃之间,波动范围为1.8和2.1℃,温度不均匀度系数在1.0以内。控温式蓄冷冷藏车与传统蓄冷车的对比试验结果表明,其平均温度波动值降低48.7%,温度绝对不均匀度系数降低50%以上,车厢质心较顶置式蓄冷车下降25.9%。研究结果可为蓄冷冷藏车的进一步优化设计与应用提供参考。     

Trace metal distribution in the bed,bank and suspended sediment of the Ravensbourne River and its implication for sediment monitoring in an urban river

Journal of Soils and Sediments - This study aims to identify a suitable sediment compartment for sediment quality monitoring by: (a) studying the concentration of trace metals (Cd, Cu, Ni, Pb and...