Replication of turkey herpesvirus and Marek's disease virus in chick embryo skin organ culture.

Turkey herpesvirus (HVT) and an attenuated Marek's disease virus (MDV) replicated in organ cultures of chick embryo skin as assessed by immunofluorescence and/or electron microscopy. HVT-specific immunofluorescent antigen was detected in the feather follicle epithelium (FFE) and in the surface layer of the skin epidermis. Electron microscopy of infected explants revealed herpes-type cytopathology. Immature particles of both viruses appeared first in the nucleus. Oval or horseshoe-shaped non-enveloped particles of HVT and enveloped virions of MDV were seen in the cytoplasm of some transitional cells. The difference in the ability of HVT and MDV to form an envelope was believed to account for the difference in their transmissibility in chickens. The results indicated that HVT replicated in the FFE and in the epidermis of the skin. However, attempts to localise the site(s) of MDV replication by electron microscopy were unsuccessful.     

Toxoplasma infection and abortion in dairy goats

Summary Serological investigation by the indirect haemagglutination test forToxoplasma antibodies was carried out in a flock of dairy goats. Antibody titres ranging from 1:4 to 1:1,024 were found in 34% of 371 apparently healthy animals. High antibody titres of 1:256 suggestive of recent infection were noted in 18 (4.9%) animals including 13 nannies. The occurrence of a number of non-brucella abortions associated with high serological titres and the isolation of the parasite from the brain tissues of an aborted foetus suggestedToxoplasma as a probable aetiologic factor. Sera having significant levels of haemagglutinating antibodies (1:128) were also found positive to the card agglutination test. Epidemiological aspects and the public health potential of subclinical toxoplasmosis in dairy goats are discussed.

---

Infecciones Y Abortos En Cabras Lecheras Debido AToxoplasma

Resumen Se realizaron investigaciones serológicas de toxoplasmosis mediante la prueba indirecta de hemaglutinación en un rebaño de cabras lecheras. Se encontraron títulos de 1:4 a 1:1024 en 34% de 371 animales aparentemente sanos. Títulos de 1:256 sugestivos de infecciones recientes, se encontraron en 18 (4.9%) animales, incluyendo 13 hembras paridas. La ocurrencia de un significativo número de abortos no asociados con brucela, títulos serológicos altos de toxoplasmosis y el aislamiento del parásito del cerebro de fetos abortados, sugiere que eltoxoplasma es el factor etiológico más importante. Se discuten aspectos epidemiológicos de importantcia para la salud pública, relacionados con el potencial de la toxoplasmosis (subclínica) en cabras lecheras.

---

Toxoplasmose Et Avortement Chez Les Chevres Latiteres

Résumé Des investigations sérologiques par la méthode de l'agglutination indirecte pour rechercher des anticorps toxoplasmiques ont été faites sur un troupeau de chèvres laitières. Des anticorps ont été mis en évidence chez 34 p.100 des 371 animaux apparemment sains à des titres allant de 1:4 à 1:1024. Des titres élevés d'anticorps atteignant 1:256 ont été relevés chez 18 (soit 4,9 p.100) des animaux comprenant 13 chèvres, ce qui fait penser à une infection récente.L'existence de nombre d'avortements non-brucelliques associés avec des titres sérologiques élevés et l'isolement du parasite des tittus cérébraux d'un foetus avorté suggerent que les Toxoplasmes en ont probablement été le facteur étiologique. Des sérums ayant des taux significativement élevés d'anticorps agglutinants (1:128) ont également été reconnus comme positifs par le test d'agglutination en EAT. Les aspects épidémiologiques et le danger potentiel pour l'homme de ces cas subcliniques de toxoplasmose chez les chèvres laitières sont discutés.

     

In ovo embryotoxicity of α-endosulfan adversely influences liver and brain metabolism and the immune system in chickens

There is a lack of laboratory-based embryonic chicken toxicity studies with the ecologically relevant low dose/s of endosulfan that utilizes a more practical approach such as the chorioallontoic membrane (CAM) injection. In this investigation, 2μg AR grade α-endosulfan/egg (40% of LD₅₀ for embryos) was injected through the CAM in 12-day-old chicken embryos and the activities of glucose-6-phosphatase (G6Pase, EC 3.1.3.9), fructose 1,6-diphosphatase (FDPase, EC 3.1.3.11), adenosine triphosphatase (ATPase, EC 3.6.1.3) and succinic dehydrogenase (SDH, EC 1.3.99.1) and DNA and RNA content in liver and brain tissues and acetyl cholinesterase (AChE, EC 3.1.1.7) in the latter were determined at 24, 48, and 72 h post-exposure. The wet weight of the embryos did not differ between groups. Following endosulfan exposure, except increase in the hepatic ATPase activity (P < 0.01), there was a significant decrease in the following parameters: G6Pase activity in both the liver and brain (P < 0.01), SDH activity in the brain (P < 0.01), brain overall DNA and RNA concentration (P < 0.05), brain AChE activity (P < 0.01). Exposure of 18-day-old embryos to 2-μg endosulfan for 24 h caused decrease (P < 0.01) in the lymphocyte count and IgG content. Histopathology of thymus and bursa of Fabricius revealed a reduction in the population of thymic follicles, smaller thymocytes with the clear vacuoles in cytoplasm and fewer bursocytes accompanied by infiltration of erythrocytes in lymphoid follicles of the endosulfan-treated embryos. It was inferred that in ovo injection of 0.041 μg/g egg weight of α-endosulfan suppress gluconeogenesis (main energy source in embryonic life), nerve transmission, and immunity.     

Genetic diversity analysis of two buffalo populations of northern India using microsatellite markers

The genetic diversity in two buffalo populations of northern India, the Bhadawari and the Tarai was assessed using a set of 22 heterologous (bovine) microsatellite markers. The average number of alleles across all loci in both populations was found to be 4.7, indicating that this set of 22 bovine microsatellite markers could be used to study genetic variation in buffalo species also. The overall polymorphic information content (PIC) value for these markers was 0.54. The average observed and expected heterozygosities for both populations were 0.59 and 0.64, respectively. Common alleles with varying allele frequencies in both populations also represented the genetic variability existing between Bhadawari and Tarai buffaloes. However the θ estimates for population differentiation indicated low levels of differentiation between the two populations. This was further supported by the low genetic distance (0.155) between Bhadawari and Tarai, which was calculated using Nei's standard genetic distance method. The present study on Bhadawari and Tarai populations represents a much‐needed preliminary effort that could be extended to other local buffalo populations of India as well.     

Soil organic carbon stock variability in the Northern Gangetic Plains of India: interaction between agro‐ecological characteristics and cropping systems

Soil organic carbon (SOC) content and its spatial distribution in the Northern Gangetic Plain (NGP) Zone of India were determined to establish the cause–effect relationship between agro‐ecological characteristics, prevailing crop management practices and SOC stock. Area Spread Index (ASI) approach was used to collect soil samples from the NGP areas supporting predominant cropping systems. Exponential ordinary kriging was found most suitable geo‐statistical model for developing SOC surface maps of the NGP. Predicted surface maps indicated that 43.7% area of NGP had 0.5–0.6% SOC, while the rest of the area was equally distributed with high (0.61–0.75%) and low (< 0.5%) SOC content levels. Averaged across cropping systems, maximum SOC content was recorded in Bhabar and Tarai Zone (BTZ), followed by Central Plain Zone (CPZ), Mid‐Western Plain Zone (MWPZ), Western Plain Zone (WPZ) and South‐Western Plain Zone (SWPZ) of the NGP. The SOC stock was above the optimum threshold (> 12.5 Mg/ha) in 97.8, 57.6 and 46.4% areas of BTZ, CPZ and MWPZ, respectively. Only 9.8 and 0.4% area of WPZ and SWPZ, respectively, had SOC stock above the threshold value. The variation in SOC stock was attributed largely to carbon addition through recycling of organic sources, cropping systems, tillage intensity, crop or residue cover and land‐use efficiency, nutrient‐use pattern, soil texture and prevailing ecosystem. Adoption of conservation agriculture, balanced use of nutrients, inclusion of legumes in cropping systems and agro‐forestry were suggested for enhancing SOC stock in the region.     

Combined application of nitrogen and phosphorus to enhance nitrogen use efficiency and close the wheat yield gap on varying soils in semi‐arid conditions

A primary driver of the wheat yield gap in Australia and globally is the supply of nitrogen (N) and options to increase N use efficiency (NUE) are fundamental to closure of the yield gap. Co‐application of N with phosphorus (P) is suggested as an avenue to increase fertiliser NUE, and inputs of N and P fertiliser are key variable costs in low rainfall cereal crops. Within field variability in the response to nutrients due to soil and season offers a further opportunity to refine inputs for increased efficiency. The response of wheat to N fertiliser input (0, 10, 20, 40 and 80 kg N ha^‐1) under four levels of P fertiliser (0, 5, 10 and 20 kg P ha^?1) was measured on three key low rainfall cropping soils (dune, mid‐slope and swale) across a dune‐swale system in a low rainfall semi‐arid environment in South Australia, for three successive cropping seasons. Wheat on sandy soils produced significant and linear yield and protein responses across all three seasons, while wheat on a clay loam only produced a yield response in a high rainfall season. Responses to P fertiliser were measured on the sandy soils but more variable in nature and a consistent effect of increased P nutrition leading to increased NUE was not measured.     

Effect of conservation agriculture on soil organic and inorganic carbon sequestration and lability: A study from a rice–wheat cropping system on a calcareous soil of the eastern Indo-Gangetic Plains

Increasing soil carbon (C) in arable soils is an important strategy to achieve sustainable yields and mitigate climate change. We investigated changes in soil organic and inorganic carbon (SOC and SIC) under conservation agriculture (CA) in a calcareous soil of the eastern Indo-Gangetic Plains of India. The treatments were as follows: conventional-till rice and wheat (CT-CT), CT rice and zero-till wheat (CT-ZT), ZT direct seeded rice (DSR) and CT wheat (ZT-CT), ZTDSR and ZT wheat without crop residue retention (ZT-ZT), ZT-ZT with residue (ZT-ZT+R), and DSR and wheat both on permanent beds with residue (PB-PB+R). The ZT-ZT+R had the highest total SOC in both 0–15 and 15–30 cm soil layers (20% and 40% higher (p < .05) than CT-CT, respectively), whereas total SIC decreased by 11% and 15% in the respective layers under ZT-ZT+R compared with CT-CT. Non-labile SOC was the largest pool, followed by very labile, labile and less labile SOC. The benefits of ZT and residue retention were greatest for very labile SOC, which showed a significant (p < .05) increase (~50%) under ZT-ZT+R compared with CT-CT. The ZT-ZT+R sequestered ~2 Mg ha⁻¹ total SOC in the 0–15 cm soil layer in 6 years, where CT registered significant losses. Thus, the adoption of CA should be recommended in calcareous soils, for C sequestration, and also as a reclamation technique.     

Impact of High Night‐Time and High Daytime Temperature Stress on Winter Wheat

High temperature is a major environmental factor that limits wheat (Triticum aestivum L.) productivity. Climate models predict greater increases in night‐time temperature than in daytime temperature. The objective of this research was to compare the effects of high daytime and high night‐time temperatures during anthesis on physiological (chlorophyll fluorescence, chlorophyll concentration, leaf level photosynthesis, and membrane damage), biochemical (reactive oxygen species (ROS) concentration and antioxidant capacity in leaves), growth and yield traits of wheat genotypes. Winter wheat genotypes (Ventnor and Karl 92) were grown at optimum temperatures (25/15 °C, maximum/minimum) until the onset of anthesis. Thereafter, plants were exposed to high night‐time (HN, 25/24 °C), high daytime (HD, 35/15 °C), high daytime and night‐time (HDN, 35/24 °C) or optimum temperatures for 7 days. Compared with optimum temperature, HN, HD and HDN increased ROS concentration and membrane damage and decreased antioxidant capacity, photochemical efficiency, leaf level photosynthesis, seed set, grain number and grain yield per spike. Impact of HN and HD was similar on all traits. Greater impact on seed set, grain number and grain yield per spike was observed at HDN compared with HN and HD. These results suggest that HN and HD during anthesis cause damage of a similar magnitude to winter wheat.