Challenge with Bovine viral diarrhea virus by exposure to persistently infected calves: protection by vaccination and negative results of antigen testing in nonvaccinated acutely infected calves

Calves persistently infected (PI) with Bovine viral diarrhea virus (BVDV) represent an important source of infection for susceptible cattle. We evaluated vaccine efficacy using calves PI with noncytopathic BVDV2a for the challenge and compared tests to detect BVDV in acutely or transiently infected calves versus PI calves. Vaccination with 2 doses of modified live virus vaccine containing BVDV1a and BVDV2a protected the calves exposed to the PI calves: neither viremia nor nasal shedding occurred. An immunohistochemistry test on formalin-fixed ear notches and an antigen-capture enzyme-linked immunosorbent assay on fresh notches in phosphate-buffered saline did not detect BVDV antigen in any of the acutely or transiently infected calves, whereas both tests had positive results in all the PI calves.     

The Political Construction of Free Trade Visions: The Geo-Politics and Geo-Economics of Australian Beef Exporting

This article contributes to emergent scholarship that questions neoliberal discourses in agricultural policy, through a case study that challenges assumptions about the role of “the market” in explaining the recent expansion of Australian beef exports. Australia is the world’s largest beef exporter and its beef exports more than doubled between the mid-1980s and the turn of the 21st century. This expansion, however, can be explained through a particular conjunction of political conditions, which are unlikely to be repeated with equal force in the current decade. Specifically, recent growth hinged upon a combination of (1) rapid growth of Japanese and Korean beef consumption in the early 1990s; (2) the operation of the US “cattle cycle” in the mid-1990s; and (3) the privileged position of Australian beef during this period, vis-à-vis Latin American competition, because of concerns over foot and mouth disease. However, because of their adherence to neoliberal assumptions about the supposed inevitability of trade liberalization, agricultural economists have mistaken these specific circumstances for a general condition in which Australian beef exports will continue growing. This deceptive envisaging of the bounty from liberalization leads not only to false expectations among industry participants, but encourages politics in which industry growth is fallaciously prioritized. Bill Pritchard, PhD, is Senior Lecturer in Economic Geography at the University of Sydney, Australia. He specializes in agri-food globalization.     

Application of for the identification and management of hybrid poplar accessions

Molecular markers are a powerful tool with many potential applications in agriculture and forestry. In particular, can provide information on the relatedness of various clones or varieties that are difficult to distinguish morphologically, thus helping in the management of plant accessions and in breeding programs. The goal of this study is to genotype 15 clones used in the Prairie Farm Rehabilitation Administration (PFRA) breeding programs. Simple Sequence Repeat (SSR, or microsatellite markers) were selected for genotyping using the polymerase chain reaction (PCR). This type of marker is considered the method of choice due to their abundance, polymorphism and reliability compared to other types of . Sixteen previously isolated and characterized in aspen (Populus tremuloides) and other poplar species (Populus spp.) were initially tested. Nine markers were selected based on the “informativeness” and the quality of the amplification products. The nine markers were combined in groups of three to improve the efficiency of the genotyping technique. Using the nine markers, the average number of alleles per locus was 5.1. The expected and observed heterozygosity ranges were 0.32 to 0.80 and 0.13 to 0.92 respectively. The results also show that it is possible to produce a unique “DNA fingerprint” specific to each of the 15 hybrid poplar clones with the nine . In this study it was possible to show that two clones, P. ‘Melville’ and P. x ‘Walker’ used in Saskatchewan have similar DNA profiles with nine markers and a combined probability of identity of 2.23×10⁻⁶ suggesting that these clones are identical. This observation will prevent unnecessary duplication of the two accessions in breeding programs. This revised version was published online in August 2006 with corrections to the Cover Date.