Biodiversity assessment and conservation strategies

The efficient representation of all species in conservation planning is problematic. Often, species distribution is assessed by dividing the land into a grid; complementary sets of grids, in which each taxon is represented at least once, are then sought. To determine if this approach provides useful surrogate information, species and higher taxon data for South African plants and animals were analyzed. Complementary species sets did not coincide and overlapped little with higher taxon sets. Survey extent and taxonomic knowledge did not affect this overlap. Thus, the assumptions of surrogacy, on which so much conservation planning is based, are not supported.     

Salmonellosis in sheep wintered outdoors on straw and sawdust pads

Extract

The wintering of sheep on outdoor straw or sawdust pads is a recent innovation which is being used increasingly on farms in Otago and Southland where the winter spelling of pasture under conditions of high stocking rates and wet soils is required. Where stock are confined on such pads for prolonged periods, the control and recognition of infectious diseases becomes of utmost importance. One such disease is salmonellosis and this paper records features of an outbreak of this disease which occurred in sheep being wintered on straw and sawdust pads in Otago. In addition, a survey was undertaken to determine the extent of salmonella infection amongst fomites and wild animals in the vicinity of the pens in which the salmonellosis occurred.     

Investigation of an outbreak of egg spoilage due to Pseudomonas spp.

Extract

Green rot in eggs is widely recognized as one of the principal causes of loss in the preservation of shell eggs. It arises from invasion of the shell contents by strains of Pseudomonas fluorescens which multiply in the albumen and elaborate the characteristic green pigment. The early stages of rotting cannot be detected in the ordinary candling by white light, but the green pigment shows strong fluorescence in ultra violet light. The yolk is also attacked and eventually the entire contents break down into a semi liquid mass with a characteristic putrid odour. At this stage the green colouration is not so obvious due to the admixture of yolk and white, and the resultant fall in pH.; the contents may then be of a yellowish green to greenish brown colour.     

Expression of behavioural signs of oestrus during mid-cycle in a dairy cow

Abstract

Extract

Routine monitoring of commercial dairy herds has confirmed the occurrence of oestrus during the luteal phase of the cycle in a small proportion (<5%) of cows (Royal et al 2000 Royal, MD, Darwash, AO, Flint, APF, Webb, R, Wooliams, JA and Lamming, GE. 2000. Detecting fertility in dairy cattle: changes in traditional and endocrine parameters of fertility. Animal Science, 70: 487–501.  [Google Scholar]). One such event occurred in one of four Friesian dairy cows being intensively monitored for progesterone and luteinising hormone (LH) concentrations in daily milk samples and 6-hourly blood samples collected from the jugular vein, throughout the postpartum period (Peters et al 1981 Peters, AR, Lamming, GE and Fisher, MW. 1981. A comparison of plasma LH concentrations in milked and suckling post-partum cows. Journal of Reproduction and Fertility, 62: 567–573.  [Google Scholar]; Fisher 1983 Fisher, MW. 1983. “The control of reproduction in the post-partum cow”. In PhD thesis, Sutton Bonington, , UK: Nottingham University.  [Google Scholar]). Consequently, the endocrine parameters associated with heat during the luteal phase were noted (Figure 1). Although an observation on a single cow, the intensive sampling data available for this animal warrant publication.     

连续14年保护性耕作对土壤总有机碳和轻组有机碳的影响

依托于2001年布设在陇中黄土高原半干旱雨养农业区的保护性耕作定位试验,于2014年测定了5种保护性耕作(免耕+秸秆覆盖NTS、免耕NT、传统耕作+秸秆翻埋TS、传统耕作+地膜覆盖TP和免耕+地膜覆盖NTP)和传统耕作T处理下小麦-豌豆双序列轮作中表层土壤(0~5、5~10、10~30 cm)总有机碳(SOC)和轻组有机碳(LFOC)在作物生育期前后的变化。结果表明:土壤总有机碳和轻组有机碳在土壤剖面上均随着土层深度的增加而降低;相比传统耕作T,NTS和TS处理能显著提高0~30 cm土层中SOC、LFOC的含量,在作物播种前较T分别提高了19.51%、64.58%和13.36%、42.08%,在收获后分别提高了28.00%、85.37%和18.61%、77.82%,而SOC、LFOC含量NT和TP处理与T处理间差异不显著;从作物播种前至收获后,各处理下0~30 cm土层SOC含量均有减小趋势,其中NTS和TS处理变化量最小,NT和TP处理加大了作物生育期间SOC和LFOC的消耗;LFOC可以灵敏地反应出土壤有机碳的变化。因此,在该区推行以免耕、秸秆覆盖为主的保护性耕作措施更有利于碳的积累和土壤质量的改善,促进该区农业的可持续发展。     

The impact of MHC diversity on cattle T cell responses

Major histocompatibility complex (MHC) genes play a key role in immunity to infectious pathogens. Their high level of diversity is a functionally important characteristic. In cattle our knowledge of MHC diversity and the functional distinction between genes is limited. Recent studies in commercially important dairy cattle populations reveal that MHC class I diversity is relatively low, although it does not appear to be declining. The presence and frequency of some genes and alleles was markedly different between geographically distinct populations, and trait selection was implicated as an influential force. Functional studies suggest that some alleles may have a disproportionally high impact on T cell responses, thus it may be important to consider their role in both disease resistance and vaccine efficacy. It is clear that increasing our knowledge of the functional capabilities of different cattle MHC class I genes is essential to maintain healthy populations in the future.     

The cattle major histocompatibility complex: is it unique?

Major histocompatibility complex (MHC) class I genes encode highly polymorphic molecules that are expressed on virtually every cell type, and have been identified in all but the most primitive vertebrates. They play a number of crucial roles in the immune response to infectious disease. Most information regarding MHC genes has been generated from humans and mice but, because of the great variability found in the MHC system, it is not always possible to extrapolate from these to other species. Many strategies have evolved to maximise the ability of the MHC to protect individuals and populations against pathogens. Cattle MHC class I genes exhibit a number of unusual features. Evidence from mapping studies, haplotype and phylogenetic analyses suggests the presence of six classical class I loci, in contrast to the more usual two or three, and these are expressed in various combinations of one, two or three on different haplotypes. Although it remains difficult to assign alleles to loci, it appears that none of the loci are expressed on all haplotypes. There is currently limited information relating to polymorphism, but various approaches suggest diversity is high, and may vary between breeds/populations. Functional consequences of variable MHC haplotype composition are discussed. Identifying unique features of the MHC in cattle will lead to new insights into evolution of the immune system.     

Paradigm shifts in vaccine development: lessons learned about antigenicity,pathogenicity and virulence of Brucellae

As part of a program to support the USDA Animal Plant Health Inspection Service Bovine Brucellosis Eradication Program, the Brucellosis Research Unit of the National Animal Disease Center (NADC) sought to develop a bovine brucellosis vaccine that would allow vaccinated animals to be distinguished from virulent field infected animals. In order to meet that goal, several avenues of research were undertaken to construct and test candidate vaccines, including Brucella abortus RB51. In early vaccine development studies, a subunit preparation obtained by extracting B. abortus with salts was studied as a candidate subunit vaccine. Later, molecular biological techniques were used both to clone genes encoding products found in the salt extract (BCSP31 and Cu–Zn SOD) and genes encoding proteins of B. abortus that were antigenic (HtrA) or possibly essential (two-component systems) for full virulence of B. abortus. In vitro systems using mammalian cells lines such as HeLa and macrophage-related were used along with the mouse model and host animal models. Results obtained at NADC and in other Brucellosis research laboratories, using survival in mammalian cell lines and the mouse model to access pathogenicity and virulence of genetically engineered strains, do not necessarily identify loci that are essential for full virulence or pathogenicity in the natural host, the bovine. Studies at NADC and other brucellosis laboratories showed that antigenicity was not a predictor of the effectiveness of a protein as a subunit vaccine.     

Predicting grey squirrel expansion in North Italy: a spatially explicit modelling approach

There is growing concern about the spread of the North American grey squirrel (Sciurus carolinensis) in northern Italy which were introduced into Piedmont in 1948. They have since spread across the Po-plain covering an area of approximately 450 km² and continue to expand their range. In parallel to what has been observed in Britain and Ireland, grey squirrels replace the native red squirrel (S. vulgaris) and damage poplar (Populus) plantations through bark-stripping. Spatially explicit population dynamics models have been successfully used to predict the spread of grey squirrels in East Anglia, England. We extended a previous approach employing a sensitivity analysis where life history and other demographic inputs are generated using Latin Hypercube Sampling from the known ranges of each input parameter, and applied it to Italy using field data collected in Piedmont. The analysis indicated that reproductive output was the most important factor determining total population size present in Piedmont. The structure and composition of woodland habitats around the introduction site suggested that initial grey squirrel expansion would have been slow and subject to emigration rates from the available habitat blocks.A comparison of the 1996 survey results with model predictions indicated that a mean litter size of three young gave the best fit with the observed distribution and we use this to predict future grey squirrel spread. We also present a worst case scenario in which grey squirrels experience improved reproductive success due to the availability of high quality habitats beyond the Po plain. In both cases they could disperse along existing continuous woodland corridors into France between 2039–2048. The case of the grey squirrel highlights the problems of implementing conservation conventions and the resulting conflicts between wildlife management, public perception and local political support and the narrow time frame that is available to control alien species effectively before it is too late. If allowed to spread, grey squirrels have the potential of becoming a European forest pest species and are likely to replace the native red squirrel in large parts of its range.     

Incidence of lameness requiring veterinary treatment in dairy cattle in Queensland

A survey of the incidence of lesions causing lameness in dairy cattle was conducted by veterinarians in 9 practices in Queensland between November 1984 and July 1985. One hundred and eighty five cases were treated in 83 dairy herds. The average incidence of lameness which required treatment by veterinarians was 2.7 cases per 100 cows per 9 months, with a range of 1.4 to 5.5% in the 9 practices. Foot lesions constituted 83.2% of all lesions; the most common being interdigital necrobacillosis (15%), deep sepsis (8.9%), white line disease (8.4 per cent), axial groove fissure (8.4%), bruised sole (5.6%) and foreign body in the sole/heel (5.6%). Sixty-five per cent of foot lesions occurred in the hind feet and 63% of these lesions occurred in the lateral claw, while 37% of foot lesions occurred in abnormally shaped claws. Limb lesions accounted for the remaining 16.8% of lesions, and 50% of these lesions occurred in the hip and stifle, while trauma was the main cause of limb lesions.