Epidemiology of ryegrass mosaic virus in South Africa

The distribution and seasonal occurrence of ryegrass mosaic virus (RMV) in South Africa was determined. Italian ryegrass plants were collected from eight different research stations twice during the growing season in 1990 and 1991. Samples were tested for the presence of RMV by means of symptomology, electron microscopy, transmission and serology. The virus was found in only three of the tested sites, namely, Nooitgedacht (Ermelo), Cedara (Pietermaritzburg) and Glen (Bloemfontein). At Nooitgedacht and Cedara, the number of infected plants increased from mid‐season to late season, while at Glen, the number of infected plants was low at mid‐season and decreased even further by late season. It is suggested that the distribution and intensity of RMV may depend on regional temperature differences.     

甘肃省张掖地区苜蓿花叶病病原的检测

2011年7月在甘肃省张掖地区发现发生花叶病的苜蓿田块,地块中病株呈现黄斑花叶、叶柄扭曲及整株矮化的症状。为明确其病原,采集病株后利用血清学和分子生物学方法对病样进行了检测。 DAS-ELISA、RT-PCR-RFLP及病毒CP基因序列测定分析结果表明,苜蓿病样受到番茄花叶病毒(Tomato mosaic virus,ToMV)和苜蓿花叶病毒(Alfalfa mosaic virus,AMV)的复合侵染。这是国际上首次报道番茄花叶病毒对苜蓿的侵染,讨论了由这两种病毒引致病害的发生与防治。     

Variation in important pasture grasses. II. Cytogenetic and reproductive variation

Abstract

The chromosome numbers and reproductive variation of seven important pasture grasses from South Africa are compared. This comparison indicates that all these species form polyploid complexes, all reproduce both sexually and either apomictically or vegetatively, and some form of hybridization or cross‐fertilization occurs in each species. The ecological success of these species can, therefore, be attributed to the fact that they combine the advantages of polyploidy and apomixis and, at the same time, bypass the disadvantages with their hybridization potential.     

The assessment and breeding of acroceras macrum stapf

Acroceras macrum Stapf is a palatable and nutritious tropical species which was popular as a pasture grass in South Africa approximately twenty five years ago. Its susceptibility to diseases and an apparent lack of seed setting ability were two serious detractions of an otherwise desirable species. A breeding programme was initiated at Cedara in 1970 and has, to some extent, overcome these deficiencies. Cytological and field investigations have revealed that tetraploid (2n= 36), pentaploid (2n= 45) and hexaploid (2n= 54) chromosome races occur and that the species is self sterile, but in certain combinations of strains of similar chromosome number and flowering date, highly cross fertile. Seed of A. macrum has a dormancy characteristic, germination improving after nine month storage. Several high yielding, disease resistant and otherwise desirable parental strains were selected for hybridization as single crosses and seed derived from these crosses has recently been planted in field experiments.     

‘n Vergelyking van wei‐ en voergewasse vir die produksie van slaglammers in die Pretoria‐ Witwatersrand‐Vereeniging(PWV)‐gebied

A comparison of pasture and fodder crops for the production of slaughter lambs in the Pretoria‐Witwatersrand‐Vereeniging (PWV) area. A number of pasture and fodder species were evaluated for the production of mutton with weancr lambs. Animal performance and meat production under three stocking rates, which were classified as light, medium, and heavy, were obtained with the aim of identifying best pasture/fodder for every season. The pastures/fodders included were Lolium multiflorum cv. Midmar and Triticum X Secale pastures under irrigation, Avena sativa and Vicia dasycarpa pasture mixture and maize crop residues under rainfed conditions, and Medicago sativa and Digitaria eriantha hay for the winter months. The spring pastures were L. multiflorum cv. Midmar, Lolium perenne cv. Nui and Dactylis glomerata cv. Hera under irrigation, while the summer pastures included Digitaria eriantha var. eriantha and M. sativa cv. Cuf 101 pastures under rainfed conditions and Cynodon dactylon cv. NK37 under irrigation. Of these, the midmar pasture for the winter and spring, maize crop residues for the winter, Hera for the spring and Cuf 101 for the summer seemed to be the best pasture of those tested in their season of use, from an animal production point of view.     

Increase in plasma total antioxidant capacity of grazing Japanese Black heifers and cows in forestland in Japan

Blood total antioxidant capacity (TAC) has become a key bio‐marker for animal health. Forest‐grazing cattle are known to forage various native plants that have high TAC. This study evaluated differences of plasma TAC between forest‐grazing (FG) and pasture‐grazing cattle (PG). Experiment 1 monitored the plasma TAC levels of 32 Japanese Black cattle. The level in PG did not change throughout the grazing period. However, that in FG, which increased from summer, was significantly higher than that in PG through fall (P < 0.05). In experiment 2, we used nine Japanese Black heifers and investigated their blood antioxidant parameters and the TAC in plants that the cattle consumed in late June and September. The plasma TAC levels in FG were significantly higher than those in PG in both periods (P < 0.05). Plasma levels of lipid peroxidation in FG tended to be lower than that in PG (P = 0.098). Furthermore, the TAC levels in various species of shrubs and trees consumed by FG were higher than those in pasture grasses. Results of this study show that plasma TAC of grazing Japanese Black cattle in forestland increase from summer through fall.     

Seasonal variation in the diet of Cape clawless otters (Aonyx capensis) in a marine habitat

Seasonal changes in the diet of Cape clawless otters Aonyx capensis feeding in the surf zone in False Bay, Western Cape Province, South Africa, were investigated by spraint (faecal) analysis. The most common prey species, during all seasons, was the Cape rock crab, Plagusia chabrus. The next most important prey species was the Cape rock lobster, Jasus lalandii, with the fish species Clinus superciliosus being equally important in winter. Other prey were fresh-water crabs, Potamonautes perlatus, octopus, Octopus granulatus, and 17 other species of fish, frogs and mammals. In winter and autumn the most important prey category was fish while in spring and summer, crustaceans were the most important. Diversity of prey was lowest in winter, increasing through the seasons from spring to autumn.     

The production of four ryegrass cultivars oversown at various seeding rates into irrigated kikuyu

An irrigated kikuyu pasture was oversown, in late March, with four ryegrass cultivars at four seeding rates at Cedara (Natal Mistbelt) and n'Tabamhlope (Highland Sourveld). The oversowing procedure shows promise with the cultivars producing well at both sites. There were no significant increases in dry matter yield from seeding rates greater than 30 kg ha^?1 . Oversowing at Cedara provided some winter dry matter production, whereas dry matter production at n'Tabamhlope commenced only in August. Kikuyu regrowth was suppressed, especially in January, but appeared to recover its yield potential by March.     

Rumen parameters of yaks (Bos grunniens) and indigenous cattle (Bos taurus) grazing on the Qinghai‐Tibetan Plateau

Yaks and indigenous Qaidam cattle and cattle‐yak crosses (C × Y) graze on the Qinghai‐Tibetan Plateau (QTP) throughout the year, but yaks are raised at higher elevations than cattle. Yaks do not receive supplementary feed whereas cattle require supplementary feed during harsh winter. We hypothesized that yaks would cope with the severe conditions of the QTP better than cattle and utilize the pasture more efficiently. We also hypothesized that differences between species would be pronounced in winter, when conditions are particularly harsh. To test these hypotheses, seasonal rumen fluid parameters of yaks, C × Y and cattle (n = 3 for each) were examined. Rumen fluid was collected in summer and winter from each genotype 2, 5 and 12 hr after a day of grazing. Concentrations of total volatile fatty acid (VFA), acetate, propionate, isobutyrate and isovalerate were greater in yaks than in cattle in summer (p < 0.05), while propionate concentration was lower in yaks than in cattle in winter (p < 0.05). Concentrations of ammonia and urea were greater (p < 0.001) in yaks than in cattle (p < 0.001) in summer, whereas, concentrations of free amino acids (AA) were greater in cattle than in yaks in summer and winter (p < 0.001). Concentrations of total VFA, acetate, propionate and butyrate decreased linearly (p < 0.05), whereas concentrations of isobutyrate and isovalerate increased linearly for yak and C × Y with sampling time (p < 0.05) in summer. In summer, concentrations of isobutyrate and isovalerate were greater in yaks than in cattle (p < 0.05). In conclusion, rumen fermentation characteristics of yaks showed that they coped better than cattle or C × Y in the harsh climate as we hypothesized. However, in contrast to our hypothesis, this emerged only in summer, when pasture was plentiful and not in winter, when pasture was scarce.     

Ongoing Activity of Toscana Virus Genotype A and West Nile Virus Lineage 1 Strains in Turkey: A Clinical and Field Survey

Toscana virus (TOSV), West Nile virus (WNV) and tickborne encephalitis virus (TBEV) are among major viral pathogens causing febrile disease and meningitis/encephalitis. The impact of these viruses was investigated at a referral centre in Ankara Province, Central Anatolia in 2012, where previous reports suggested virus circulation but with scarce information on clinical cases and vector activity. Serum and/or cerebrospinal fluid samples from 94 individuals were evaluated, in addition to field‐collected arthropod specimens that included 767 sandflies and 239 mosquitoes. Viral nucleic acids in clinical samples and arthropods were sought via specific and generic nested/real‐time PCRs, and antibody responses in clinical samples were investigated via commercial indirect immunofluorescence tests (IIFTs) and virus neutralization. A WNV antigen assay was also employed for mosquitoes. WNV neuroinvasive disease has been identified in a 63‐year‐old male via RNA detection, and the WNV strain was characterized as lineage 1. TOSV infections were diagnosed in six individuals (6.3%) via RNA or IgM detection. Partial sequences in a 23‐year‐old female, presented with fever and transient pancytopenia, were characterized as TOSV genotype A. Febrile disease with arthralgia and/or peripheral cranial nerve involvement was noted in cases with TOSV infections. Previous WNV and TOSV exposures have been observed in 5.3% and 2.1% of the subjects, respectively. No confirmed TBEV exposure could be identified. Morphological identification of the field‐collected mosquitoes revealed Culex pipiens sensu lato (74.4%), Anopheles maculipennis (20.9%), An. claviger (2.1%) and others. Sandfly species were determined as Phlebotomus papatasi (36.2%), P. halepensis (27.3%), P. major s. l. (19.3%), P. sergenti (8.9%), P. perfiliewi (4.4%), P. simici (2.6%) and others. Viral infections in arthropods could not be demonstrated. TOSV genotype A and WNV lineage 1 activity have been demonstrated as well as serologically proven exposure in patients. Presence of sandfly and mosquito species capable of virus transmission has also been revealed.     

Impact of Prosopis (mesquite) invasion and clearing on vegetation species composition and diversity in semi-arid Nama-Karoo rangeland,South Africa

The Nama-Karoo biome occupies 28% of South Africa’s land area. Alien leguminous trees of the genus Prosopis have invaded large tracts of Nama-Karoo rangeland. We evaluated the impact of Prosopis invasion and clearing on vegetation species composition and diversity (alien and indigenous species richness and cover) in Nama-Karoo rangeland on two sheep farms in the Beaufort West district of the Western Cape province of South Africa. Our results suggest that Prosopis invasion and clearing can significantly change Nama-Karoo rangeland species composition. Invasion and clearing appear to have no effect on alien species richness. Invasion, however, increases alien species cover, while clearing restores it to pre-invasion levels. In contrast, invasion reduces indigenous species richness while clearing restores it to pre-invasion levels. Invasion appears to have no effect on indigenous species cover. This lack of effect appears to be the serendipitous result of a site-specific trade-off between a decline in cover of grasses that are negatively affected by Prosopis invasion and a concomitant increase in the cover of positively affected grasses. Clearing increases indigenous species cover to above pre-invasion levels. The higher than usual indigenous species cover after clearing could be a transient legacy of Prosopis soil nutrient enrichment.     

Grassland research priorities: Ideas for the future

Abstract

Four levels of available dry matter (DM) were maintained on a continuously grazed irrigated Midmar Italian ryegrass (Lolium multiflorum Lam.) pasture by means of a “put‐and‐take” grazing procedure. The pasture was stocked with three successive sets of weaned lambs in winter, spring and early summer respectively. The relation between average daily gains (ADG) and available DM was positively linear At equivalent levels of available DM, gains were greater in spring than in either the winter and summer periods (P ≤0,01), but there were no differences in gains between winter and summer. There was a negative linear relation between average stocking rate (the rate required to achieve a given level of herbage availability) and available DM. Stocking rates in spring and summer were not significantly different, but both were higher (P≤0,01) than those in winter. Within the range of the differential treatments applied, relations between stocking rate and ADG were negatively linear, and there was an interactive effect (P≤0,01) between stocking rate and grazing period. Changes in ADG with a unit change in stocking rate were greatest in winter, intermediate in summer and least in spring. Gains/ha were curvilinearly related to available DM. The curves indicate that the amounts of available DM required for maximum gains/ha were least in spring, intermediate in summer and greatest in winter.

From a serial cutting trial conducted concurrently with the grazing, a growth rate curve was developed for Midmar ryegrass. This curve had two maxima, with the maximum growth rate in spring being more than double that in autumn. The in vitro digestible organic matter content and crude protein content decreased from 80,6% and 24,1% in autumn to 63,1% and 10,6%, respectively, in summer. Crude fibre content increased from 10,1 % in autumn to 30,1 % in summer.     

Infection with Menangle virus in flying foxes (Pteropus spp.) in Australia

Objective To examine flying foxes (Pteropus spp.) for evidence of infection with Menangle virus. Design Clustered non‐random sampling for serology, virus isolation and electron microscopy (EM). Procedure Serum samples were collected from 306 Pteropus spp. in northern and eastern Australia and tested for antibodies against Menangle virus (MenV) using a virus neutralisation test (VNT). Virus isolation was attempted from tissues and faeces collected from 215 Pteropus spp. in New South Wales. Faecal samples from 68 individual Pteropus spp. and four pools of faeces were examined by transmission EM following routine negative staining and immunogold labelling. Results Neutralising antibodies (VNT titres ≥ 8) against MenV were detected in 46% of black flying foxes (P. alecto), 41% of grey‐headed flying foxes (P. poliocephalus), 25% of spectacled flying foxes (P. conspicillatus) and 1% of little red flying foxes (P. scapulatus) in Australia. Positive sera included samples collected from P. poliocephalus in a colony adjacent to a piggery that had experienced reproductive disease caused by MenV. Virus‐like particles were observed by EM in faeces from Pteropus spp. and reactivity was detected in pooled faeces and urine by immunogold EM using sera from sows that had been exposed to MenV. Attempts to isolate the virus from the faeces and tissues from Pteropus spp. were unsuccessful. Conclusion Serological evidence of infection with MenV was detected in Pteropus spp. in Australia. Although virus‐like particles were detected in faeces, no viruses were isolated from faeces, urine or tissues of Pteropus spp.     

Temporal and spatial patterns of abundance and breeding activity of Namaqua sandgrouse in South Africa

We examined various measures of temporal and spatial patterns of abundance and breeding activity of Namaqua sandgrouse Pterocles namaqua (presumably mostly for P. n. furvus) in South Africa. Bird-atlas maps indicating reporting-rates and extensive-counts showed that the majority of Namaqua sandgrouse concentrate in Bushmanland, in the north-western Cape Province, from December to March. From April to July the sandgrouse move north and east of Bushmanland and apparently return to Bushmanland from August to November. This west-east movement occurs at a relatively constant rate of 30-50 km per month. Only 15% of the sandgrouse ringed at an estate within the eastern part of this species range returned the following winter. Follicle diameter and brood-patch measurements increased significantly from July to August, at the time when the majority of birds leave the estate. Belly-soaking was more prevalent in early summer in Bushmanland than in any season in the east. South African populations of Namaqua sandgrouse are partial migrants which breed primarily in early summer (October - November) in Bushmanland.     

Effect of season of burning on grass recovery in the false thornveld of the eastern cape

Abstract

Season of burning is one of the most controversial questions concerning the use of fire in veld management. In the summer rainfall areas of South Africa the generally accepted rule of burning only after the first spring rains has proven ineffectual when using fire to control bush encroachment because the fires are too cool when burnt at this time. It was therefore decided to investigate the effect of burning on the regrowth of grass when applied during mid‐winter, spring, late spring and early summer. The results showed that burning when the grass was dormant (mid‐winter) had no deleterious effect on the recovery of grass when compared with burning after the first spring rains (spring). Conversely burning when the grass was actively growing (early summer) seriously retarded its regrowth.     

Climate and the evolution of group-living behaviour in the armadillo lizard (Ouroborus cataphractus)

We evaluated the hypothesis that the regular use of the southern harvester termite, Microhodotermes viator, as food source by the armadillo lizard, Ouroborus cataphractus, originated as an adaptation to survive the summer dry season in a climatic regime where rainfall is highly seasonal. To do so, we determined the most important climatic predictors of the geographical range of this species. Climatic data were obtained for 130 localities where O. cataphractus is known to occur and 168 adjacent localities where it is known to be absent. For each locality, data for 10 climatic variables were extracted from the South African Atlas of Agrohydrology and Climatology database. We constructed a forward stepwise logistic regression model of the probability of O. cataphractus occurrence, based on the set of 10 climatic variables. The best model included, in order of importance, average monthly summer rainfall, mean annual precipitation, average monthly solar radiation, and the ratio of winter rainfall over summer rainfall as most significant predictors. The selected model predicted 88.80% of the presences correctly and 85.52% of the absences. In essence, O. cataphractus is restricted to the winter rainfall zone of South Africa, excluding the high-rainfall southwestern section. We postulate that the highly predictable seasonal rainfall and the ameliorating effect of the Atlantic Ocean on climates in the Namaqualand region, in particular, have provided a unique selective regime for the origin of group-living in O. cataphractus. Dependence on M. viator as food source developed to survive the summer-autumn period of low food availability and resulted in the evolution of heavy armour and group-living behaviour. The moderate winters and early spring temperatures allowed full capitalization on high arthropod abundance during winter–spring, thereby overriding the negative impacts of armour and group-living on foraging efficiency at the home crevice.     

Dry matter yield and nutritional value of companion crops,intercropped with maize,for grazing purposes in northwestern KwaZulu-Natal

The northwestern part of KwaZulu-Natal (KZN) in South Africa is suitable for sheep farming as well as crop production. However, there are some constraints to animal production due to the low quality of natural vegetation during winter. Alternative winter feeding strategies have been suggested from research conducted in similar vegetation types in other parts of South Africa. Grazing maize is a potential alternative fodder source but its low crude protein might be a limitation to acceptable livestock production. This preliminary study investigated the potential of inter-cropping maize with high protein content crops for providing sheep with fodder of acceptable quality during winter in northwestern KZN.

Raphanus sativus (Japanese radish), Ornithopus sativus (serradella) and Vicia dasycarpa (grazing vetch) showed promising results in terms of dry matter yield and nutritional value. The production of Pennisetum glaucum (babala) and Avena sativa (oats) was relatively high. However, the nutritional value of both these species was marginal. Glycine max (soybeans) and Lablab purpureus (dolichos) showed good and above required nutritional properties, but dry matter yield was low.     

Small‐scale reseeding trials in arid rangeland: Effects of rainfall,clearing and grazing on seedling survival

Abstract

Seeds of four indigenous plant species were sown in 1990 in small‐scale field trials in an arid, non‐seasonal rainfall region of the southern Karoo, South Africa. Seeds of a winter annual Tetragonia echinata (Aizoaceae) showed innate dormancy but those of three perennial shrubs Pteronia empetrifolia, P. pollens and Osteospermum sinuatum (all Asteraceae) emerged only after the first substantial autumn rain. In good rangeland, seedling growth and survival was better in clearings than in undisturbed vegetation. In poor, continuously‐grazed rangeland, sheep had more influence on growth and survival of O. sinuatum seedlings than did vegetation clearing. These findings should be tested by means of large‐scale trials replicated in time and space.     

Grassland bird response to vegetation structural heterogeneity and clearing of invasive bramble

Spatial and temporal patterns of disturbance and the subsequent heterogeneity are critical in maintaining biodiversity within grassland ecosystems. Grassland birds have evolved within this ‘shifting mosaic’ to become reliant on specific habitat characteristics maintained under varying levels of both natural and anthropogenic disturbance. Unfortunately, grasslands in South Africa have been extensively transformed and remain poorly conserved, threatening grassland avifauna. Mistbelt grassland is a threatened vegetation type endemic to the province of KwaZulu-Natal, of which only 0.3% is formally protected. This study investigated seasonal and patch type heterogeneity in a Mistbelt grassland avian community by determining avian community structure and composition in four patch types, i.e. i) untransformed open grassland, ii) burnt grassland, iii) bramble-invaded and, iv) bramble-cleared grassland, during winter and summer. Avian assemblages were significantly different between the different patch types for each season. The bramble patch type negatively affected grassland bird species diversity. Bramble-cleared grassland and untransformed grassland had similar vegetation structure and avian communities in the summer, suggesting that the grassland bird community benefitted soon after the clearing of invasive vegetation. This study provides further evidence that bird diversity is enhanced in structurally heterogeneous grassland landscapes. Furthermore, the protection and appropriate management of privately owned Mistbelt grassland, conserved in the form of rangeland, is an important refuge for threatened and endemic avifauna, such as the globally-threatened blue swallow (Hirundo atrocaerulea) and wattled crane (Bugeranus carunculatus).     

Animal models of henipavirus infection: A review

Hendra virus (HeV) and Nipah virus (NiV) form a separate genus Henipavirus within the family Paramyxoviridae, and are classified as biosafety level four pathogens due to their high case fatality rate following human infection and because of the lack of effective vaccines or therapy. Both viruses emerged from their natural reservoir during the last decade of the 20th century, causing severe disease in humans, horses and swine, and infecting a number of other mammalian species. The current review summarises current published data relating to experimental infection of small and large animals, including the natural reservoir species, the Pteropus bat, with HeV or NiV. Susceptibility to infection and virus distribution in the individual species is discussed, along with the pathogenesis, pathological changes, and potential routes of transmission.