Topography of the northern hemisphere of Mercury from MESSENGER laser altimetry

Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history.     

Poult malabsorption syndrome. III. Skeletal lesions in market-age turkeys.

Skeletal deformities, a major contributing factor to economic losses in market-age turkeys, may be associated with the poult malabsorption syndrome. A study was performed to determine whether the naturally occurring malabsorption syndrome produces skeletal lesions in turkeys at market age. Poults were placed on litter on which poults had previously developed malabsorption. Exposed poults developed enteric disease with 21% mortality during the first 3 weeks. Controls had no enteric disease and no mortality. At the end of the study, 20-week-old exposed turkeys weighed 0.621 kg (5%) less than controls and had a higher incidence of angular limb deformities with significantly higher angulation scores. Exposed turkeys also had a greater incidence of rotated tibias and bowed tibias. The mechanical property of tibial shear strength was significantly lower in turkeys that had survived the earlier poult malabsorption syndrome.     

Measuring the benefits of disease control: Relationship between herd structure,productivity and health

Summary The influence of calving percentage and mortality levels on heard structures is studied. Standard herd structures with set levels of mortality are calculated for comparison with field data. Herd structures from field surveys in Zambia are studied in order to determine how these can be used to gain more information about herd input and output dynamics. Methods of calculating off-take and the problems relating to making such calculations are discussed.

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Resumen Se estudió la influencia de los niveles de nacimientos y mortalidad en la estructura del hato. Se calcularon estructuras de hatos estandar, con niveles preconcebidos de mortalidad, para compararlos con datos de campo. Se estudiaron las estructuras de hatos en Zambia datos adquiridos en el campo, para determinar cómo éstos pueden utilizarse para obtener mayor información acerca de la dinámica costo-beneficio. Se discuten los métodos para calcular las ganancias y los problemas relacionados con estos cálculos.

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Résumé L'influence du niveau des intrants et des extrants (taux de vêlage et mortalité) sur la structure des troupeaux est étudiée. Des compositions standards avec des taux de mortalité pré-établis sont calculées pour permettre la comparaison avec les données recueillies sur le terrain. A partir d'enquêtes conduites en Zambie, la structure des troupeaux est étudiée en vue de déterminer comment ces résultats peuvent être utilisés pour accro?tre les données relatives à la dynamique des ressources et des emplois pour un troupeau donné. Les méthodes de calcul du taux d'exploitation et les problèmes relatifs à l'élaboration de ces calculs sont discutés.

     

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.     

Seroprevalences of vector-transmitted infections of small-holder dairy cattle in coastal Kenya

A cross-sectional study was carried out from July to September 1989 in Kaloleni Division, Coast Province, Kenya to estimate the prevalence of vector-transmitted diseases in small-holder dairy cattle and to identify the risk factors associated with different management systems. One hundred and thirty of the 157 herds with dairy cattle in Kaloleni Division were surveyed. These were from three agro-ecological zones (coconut-cassava, cashew nut-cassava and livestock-millet), comprised two management systems (stall-feeding and herded grazing) and were herds with either dairy cattle only or with Zebu and dairy cattle. A formal questionnaire sought answers to questions on cattle health and management practices. A total of 734 dairy and 205 Zebu cattle in 78 dairy and 52 mixed (dairy and Zebu) herds were sampled and screened for haemoparasites (Trypanosoma, Anaplasma, Babesia, and Theileria infections). Sera were tested for antibodies to Theileria parva, using the schizonts-antigen indirect fluorescent-antibody (IFA) test and to antibodies for Babesia bigemina and antigens to Anaplasma marginale by enzyme-linked immunosorbent assay (ELISA). Packed-cell volume (PCV) also was measured. Tick-control measures were practised by all except three of the farmers. Despite this, overall seroprevalence to T. parva was >70%--suggesting either that control practices were not strictly implemented or they were ineffective. The seroprevalence of T. parva in adult cattle kept in stall-feeding systems in the coconut-cassava zone was significantly lower (57+/-8% (S.E.)) than in herded-grazing systems (79+/-3%) and there was no association between antibody prevalence and age of cattle in this zone. Antibody prevalences in cattle in the cashew nut-cassava and the drier livestock-millet zone increased with age. Cattle in herded-grazing systems had an overall lower seroprevalence of T. parva infection in the livestock-millet zone (45+/-6%) than in the other two zones.Analysis was confined to the coconut-cassava zone for B. bigemina and to the coconut-cassava and cashew nut-cassava zones for A. marginale. Mean prevalences of B. bigemina were 40.9+/-9 and 73+/-6% for dairy cattle under stall-feeding and herded-grazing systems, respectively, and increased with age. Antigen prevalences of A. marginale were over 80% in all age groups of cattle in the coconut-cassava and cashew nut-cassava zones. Overall trypanosome prevalence in cattle was <1%. Trypanocidal treatment was uncommon. The variations in antibody prevalence associated with risk factors such as feeding system, agro-ecological zone and age of animal suggest that management system influenced exposure to tick-borne infection (particularly, T. parva infections) in small-holder dairy cattle in coastal Kenya.     

The effects of hypoxia,in vivo,on red blood cell β-adrenoceptors in the rainbow trout,Oncorhynchus mykiss

Rainbow trout, Oncorhynchus mykiss, were exposed to 48h of environmental hypoxia (water partial pressure of oxygen = 8.0 kPa) at either 5 or 15°C. Blood was sampled during hypoxia via a dorsal aorta cannula to measure arterial blood partial pressure of oxygen and plasma catecholamine concentrations. After 48h, the number (B_max) and dissociation constant (K_d) of red blood cell surface -adrenoceptors were determined using a radioligand-displacement binding assay. At 5°C, plasma catecholamine levels were elevated at 24h whereas at 15°C, levels were elevated at 48h. At either temperature, following 48h of hypoxia, there was no change in B_max or K_d of red blood cell surface -adrenoceptors, compared to normoxic control fish. This study demonstrates that chronic exposure to moderate hypoxia does not affect the number or affinity of cell surface -adrenoceptors on trout red blood cells.     

Enterocolitis caused by Ehrlichia sp. in the horse (Potomac horse fever)

Potomac horse fever was reproduced in 15 ponies by transfusion of whole blood originally from two natural cases and subsequently from ponies infected by the transfusions. Incubation periods varied from 9 to 15 days. Affected ponies developed varying degrees of fever, diarrhea, anorexia, depression, and leukopenia. Eleven affected ponies were killed, three died in the acute phase of the disease, and one did not show clinical signs. The most consistent post-mortem findings were fluid contents in the cecum and large colon, and areas of hyperemia (of inconstant degree and distribution) in mucosae of both small and large intestines. Multifocal areas of necrosis occurred in mucous membranes. Ehrlichial organisms were most common in the cytoplasm of epithelial cells, macrophages, and mast cells of the large colon.     

A study of health and productivity of traditionally managed cattle in Zambia

A three-tiered survey was devised comprising a detailed questionnaire, a serological survey and a sentinel herd scheme for disease surveillance. The survey was carried out in the traditional farming sector in 7 districts of Zambia to obtain background information on cattle management and productivity, data on the prevalence of tick-borne and other disease problems in these areas and to monitor changes in individual herds.In the questionnaire survey, 288 farmers were interviewed. They owned a total of 15 360 head of cattle, representing approximately one percent of the national herd. Mean herd sizes ranged from 31 to 114 for each district. Mean calving percentages were 44–80%. Average national offtake from these herds was 10%. Calf mortality rates ranged from 4 to 32%, while adult yearly mortality rates ranged from 4 to 16%. Factors affecting the regional variation of these figures are discussed.     

Can epidemiology and economics make a meaningful contribution to national animal-disease control?

The general role of veterinary epidemiology and economics to national animal-disease control throughout the world is considered for the four main groupings of animal diseases: zoonotic, food-borne, endemic and epidemic diseases. This is done by considering how veterinary epidemiology and economics has contributed to priority setting (which diseases come first?), decision-making (for a given disease, which strategy is best?), and disease control implementation (how can optimal delivery and adoption of selected interventions best be achieved?). Within each of these categories, progress made and future opportunities are discussed. In addition, a review is made of how veterinary epidemiology and economics has been institutionalised. We conclude that veterinary epidemiology and economics holds a unique role in the development of national policies and strategies for improved animal health world-wide. However, we consider that we must capitalise more on the unique comparative advantage of the partnership between veterinarians and agricultural economists. We believe that much remains to be done to improve the "institutionalisation" of veterinary epidemiology and economics, and the adoption and impact of the products of our unique partnership, particularly in countries of the developing world.