Risk factors for bovine mastitis in the Central Province of Sri Lanka

A study of the risk factors associated with mastitis in Sri Lankan dairy cattle was conducted to inform risk reduction activities to improve the quality and quantity of milk production and dairy farmer income. A cross-sectional survey of randomly selected dairy farms was undertaken to investigate 12 cow and 39 herd level and management risk factors in the Central Province. The farm level prevalence of mastitis (clinical and subclinical) was 48 %, similar to what has been found elsewhere in South and Southeast Asia. Five cow level variables, three herd level variables, and eight management variables remained significant (p?相似文献   

Genetic differentiation at microsatellite loci among populations of Mycosphaerella graminicola from California, Indiana, Kansas, and North Dakota

Mycosphaerella graminicola causes Septoria tritici blotch (STB) in wheat (Triticum aestivum) and is considered one of the most devastating pathogens of that crop in the United States. Although the genetic structures of M. graminicola populations from different countries have been analyzed using various molecular markers, relatively little is known about M. graminicola populations from geographically distinct areas of the United States and, in particular, of those from spring versus winter wheat. These are exposed to great differences in environmental conditions, length and season of host-free periods, and resistance sources used in geographically separated wheat breeding programs. Thus, there is more likely to be genetic differentiation between populations from spring versus winter wheat than there is among those within each region. To test this hypothesis, 330 single-spore isolates of M. graminicola representing 11 populations (1 from facultative winter wheat in California, 2 from spring wheat in North Dakota, and 8 from winter wheat in Indiana and Kansas) were analyzed for mating type frequency and for genetic variation at 17 microsatellite or simple-sequence repeat (SSR) loci. Analysis of clone-corrected data revealed an equal distribution of both mating types in the populations from Kansas, Indiana, and North Dakota, but a deviation from a 1:1 ratio in the California population. In total, 306 haplotypes were detected, almost all of which were unique in all 11 populations. High levels of gene diversity (H = 0.31 to 0.56) were observed within the 11 populations. Significant (P ≤ 0.05) gametic disequilibrium, as measured by the index of association (rBarD), was observed in California, one Indiana population (IN1), and three populations (KS1, KS2, and KS3) in Kansas that could not be explained by linkage. Corrected standardized fixation index (G″(ST)) values were 0.000 to 0.621 between the 11 populations and the majority of pairwise comparisons were statistically significant (P ≤ 0.001), suggesting some differentiation between populations. Analysis of molecular variance showed that there was a small but statistically significant level of genetic differentiation between populations from spring versus winter wheat. However, most of the total genetic variation (>98%) occurred within spring and winter wheat regions while <2% was due to genetic differentiation between these regions. Taken together, these results provide evidence that sexual recombination occurs frequently in the M. graminicola populations sampled and that most populations are genetically differentiated over the major spring- and winter-wheat-growing regions of the United States.     

Evaluating the Impacts of Forest Management Policies and Community-Level Institutions in the Buffer Zone of Chitwan National Park,Nepal

A Master Plan for Nepal’s Forestry Sector (MPFS), enacted in 1989, and subsequent legislation laid the foundation for modern community-based forest management in Nepal. In 2014, the MPFS reached the end of its 25-yr lifespan, after successfully ushering in significant institutional changes that fundamentally transformed the management of Nepal’s forests, mostly through devolving management and benefits from the national level to local communities. Here, we use the 25-yr anniversary of the MPFS to explore forest cover trends in the buffer zone surrounding Chitwan National Park (CNP). Landsat imagery was used for the years 1989, 2005, and 2013 to compute a normalized difference vegetation index (NDVI) to analyze trends in forest cover for 36 buffer zone village development committees (VDCs). The analysis, covering approximately 1,267 km², found that since the MPFS was enacted, there was first a continued decrease in forest cover, followed by a significant recovery. These data offer insight into the success of modern community-based forest management policies and supporting institutions, and provide a model for other efforts to conserve forest resources in Nepal and elsewhere.     

Exploration of ready-to-eat soft Bora rice genotypes of Assam for submergence tolerance

Journal of Crop Science and Biotechnology - Assamese Bora rice lines are valuable genetic resource for their socio-economic importance and traditional usage. Being lowland rice lines of upper...     

Options for converting a clone trial of Eucalyptus camaldulensis into a clonal seed orchard considering gain,fertility and effective clone number

We evaluated a clone trial comprised of 20 ramets each of 40 Eucalyptus camaldulensis clones for growth and fertility at 4 years of age. The clones differed significantly in growth with 65–100 % survival in 38 clones while two clones had low survival(40 and 10 %).Fecundity was high and fertility variation low, as indicated by the sibling coefficient value(W = 1.4) with 55 % of clones contributing 80 % of the fruits. Thinning strategies were considered to convert the clone trial to a clonal seed orchard and enhance both gain and diversity in seed crop.When clones were selected based on growth without considering fertility, truncation selection(to retain clones with higher DBH than the trial mean value) would give 8 %gain, but 59 % reduction in effective population size(Ne).Gain and predicted diversity(Ne) was highest when ramets were selected in linear proportion to the breeding value of each clone. Mass selection with the same intercept(for DBH) as truncation selection would give a moderate 3 %gain, but over two times higher predicted Nethan truncation selection. When fertility of retained trees was considered after thinning, mass selection would yield 52 %effective contribution from the orchard trees compared to only 30 % contribution from truncation selection and linear thinning. Higher representation of superior clones in linear thinning and mass selection would lead to greater fertilityvariation and over 30 % reduction in effective clone number(Nc) from that predicted(Ne, assuming equal fertility among ramets) before thinning.     

Morphological,pathological and genetic variations among isolates of <Emphasis Type="Italic">Cochliobolus sativus</Emphasis> from Nepal

Spot blotch, caused by Cochliobolus sativus (Ito & Kuribayashi) Drechs. ex Dastur, is one of the important diseases of wheat worldwide. The main objective of this study was to investigate the phenotypic and genotypic variability among C. sativus isolates from the hills and plains in Nepal. A total of 48 monoconidial isolates of C. sativus from the hills (n = 24 isolates) and plains (n = 24 isolates) in Nepal were analyzed for morphology, aggressiveness and genetic structure. C. sativus isolates were grouped into three categories on the basis of their colony texture and mycelia colour. Thirteen isolates from the hills and plains belonging to three morphological groups were randomly selected and evaluated for aggressiveness on eight wheat cultivars (Chirya 1, Chirya 7, Milan/Shanghai 7, SW 89–5422, PBW 343, BL 1473, BL 3036, and RR 21) at the seedling stage. Nonparametric analysis revealed that the isolates from the plains (median disease rating of 5) were significantly (P = 0.0001) more aggressive than the isolates from the hills (median disease rating of 3). A significant (P = 0.0001) isolate by cultivar interaction was demonstrated and the isolates from the same geographic region and morphological group displayed different degrees of aggressiveness on wheat cultivars tested. Combined IS-PCR and rep-PCR analyses revealed moderate gene diversity (H = 0.24 and 0.25 for the hills and plains, respectively). Low linkage disequilibrium (LD) value and non-significant (P = 0.001) population differentiation (G″_ST = 0.05) were detected, indicating that isolates of C. sativus from the hills and plains in Nepal were genetically similar. Analysis of molecular variation (AMOVA) revealed low (7%) levels of genetic variation between the hill and plain populations, whereas >93% of genetic variation was found within populations. Overall, C. sativus isolates from Nepal are pathologically and genetically diverse, and such information will be useful in developing wheat cultivars resistant to C. sativus.     

Association mapping of quantitative resistance to Phaeosphaeria nodorum in spring wheat landraces from the USDA National Small Grains Collection

Stagonospora nodorum blotch (SNB), caused by Phaeosphaeria nodorum, is a destructive disease of wheat (Triticum aestivum) found throughout the United States. Host resistance is the only economically feasible option for managing the disease; however, few SNB-resistant wheat cultivars are known to exist. In this study, we report findings from an association mapping (AM) of resistance to P. nodorum in 567 spring wheat landraces of diverse geographic origin. The accessions were evaluated for seedling resistance to P. nodorum in a greenhouse. Phenotypic data and 625 polymorphic diversity array technology (DArT) markers have been used for linkage disequilibrium (LD) and association analyses. The results showed that seven DArT markers on five chromosomes (2D, 3B, 5B, 6A, and 7A) were significantly associated with resistance to P. nodorum. Genetic regions on 2D, 3B, and 5B correspond to previously mapped quantitative trait loci (QTL) conferring resistance to P. nodorum whereas the remaining QTL appeared to be novel. These results demonstrate that the use of AM is an effective method for identifying new genomic regions associated with resistance to P. nodorum in spring wheat landraces. Additionally, the novel resistance found in this study could be useful in wheat breeding aimed at controlling SNB.