No abstract

Spiroplasma, small motile wall-less bacteria, are linked by molecular and serological studies to the transmissible spongiform encephalopathies (TSEs), which include scrapie in sheep, chronic wasting disease (CWD) in deer and Creutzfeldt-Jakob disease in humans. In this study, two experiments were undertaken to determine the role of spiroplasma in the pathogenesis of TSE. In experiment 1, Spiroplasma mirum, a rabbit tick isolate that had previously been shown to experimentally induce spongiform encephalopathy in rodents, was inoculated intracranially (IC) into ruminants. S. mirum-inoculated deer manifested clinical signs of TSE after 1.5 to 5.5 months incubation. The deer, as well as sheep and goats, inoculated with S. mirum developed spongiform encephalopathy in a dose-dependent manner. In experiment 2, spiroplasma closely related to S. mirum were isolated from TSE-affected brains via passage in embryonated eggs, and propagated in cell-free M1D media. Spiroplasma spp. isolates from scrapie-affected sheep brain and from CWD-affected deer brain inoculated IC into sheep and goats induced spongiform encephalopathy closely resembling natural TSE in these animals. These data show spiroplasma to be consistently associated with TSE, and able experimentally to cause TSE in ruminant animal models, therein questioning the validity of studies that have concluded the prion, a miss-folded protease-resistant protein that builds up in TSE brains during the course of the disease, to be the sole causal agent. The spiroplasma infection models reported here will be important for investigating factors involved in the pathogenesis of TSE since ruminants are the natural hosts.

An adequate and clean artificial insemination (AI) technique is recommended to improve reproductive outcomes in dairy cattle. The objective of this study was to evaluate the effectiveness of using protective plastic sheaths (PS) to minimize contamination of the AI catheter (AIC) on pregnancies per AI (PAI) in lactating dairy cattle. Lactating cows housed in freestall barns on a commercial dairy farm were presynchronized with 2 injections of PGF(2α) given 14 d apart (starting at 26±3 d postpartum) followed by Ovsynch (GnRH-7 d-PGF(2α)-56 h-GnRH-16 h-timed-AI; TAI) 12 d later. Cows presenting signs of standing heat any time during the protocol received AI, whereas the remaining animals were subjected to TAI 16h after second Ovsynch GnRH. At the time of AI (1 AI technician), 996 services from 773 lactating dairy cows were randomly assigned to 1 of the 2 groups; with (TRT, n=487) or without (CON, n=509) the use of disposable PS. In the TRT group, the AIC protected with a PS was introduced into the vagina; once in the cranial portion of the vagina adjacent to the cervical os, the PS was pulled back and only the AIC was manipulated through the cervix into the uterine body for semen deposition. In the CON group, cows were inseminated without the use of PS. Samples were taken with a sterile cotton swab from the tip of the AIC (n=51) after AI from both treatment groups. Pregnancy diagnosis was determined by ultrasonography 39±3 d after AI. Cultured swab samples revealed that the use of PS was effective in minimizing contamination of the AIC (positive bacterial growth: TRT=61.53% vs. CON=100%). Overall, the proportion of cows pregnant was greater for cows in TRT (42.7) compared with the CON group (36.1). For first services postpartum, PAI did not differ between CON (43.01%, n=194) and TRT (43.8%, n=182) groups. However, PAI for second or greater services were greater in TRT (43.8%, n=305) than in CON cows (32.3%, n=315). Results from this study provided evidence that the use of PS during AI improved PAI for second or greater services in lactating dairy cows. Performing a clean AI technique through the use of PS may be an effective strategy to improve reproductive outcomes in dairy cattle.

A Kramer-Collins Spore Sampler was operated in cotton intervals throughout the season. Spore counts increased soon fields at several locations in Louisiana during 1974 and 1975 after the onset of flowering, with peak spore catches approxto monitor the spore dispersal of boll-rotting fungi. Conidia imately 50 days later. Spore numbers decreased rapidly after of Alternaria gossypina, Curvularia spp., Diplodia the peak periods of spore dispersal. The first rotted bolls were gossypina, Fusarium spp., and Helminthosporium gossypii observed soon after the time of peak spore catches. With the were counted in hourly samples taken over 24-hr periods at exception of Alternaria, most spores were detected at night.

Jodon is an F 6 bulk of a single progeny row in the breeding nursery at Crowley in 1987, selection 8713958. It was evaluated in the preliminary yield nursery (experimental designation 8802506) in 1988 and entered in the Cooperative Uniform Regional Rice Nurseries (URRN) in 1989 with the designation RU8902031. Jodon has a semidwarf plant type and is similar in height to 'Cypress', Lemont, and 'Maybelle' (2). In the URRN grown in Louisiana, Arkansas, Mississippi, and Texas from 1989 to 1993, the average height of each of these cultivars was 97 cm. The flag leaf of Jodon is relatively narrow, remains erect through physiological maturity, and tends to droop as plants approach harvest maturity. Days to 50% heading averaged 81 for Jodon, 86 for Cypress, 86 for Lemont, and 74 for Maybelle (URRN, 1989-1993). The leaves, lemma, and palea of Jodon are glabrous. The spikelet is straw-colored and may be awned or awnless. The apiculus is purple at heading, but the color fades as the grain approaches maturity. The grain is nonaromatic and nonglutinous and has a light brown pericarp. The overall average yield of Jodon in the URRN in the four major rice producing states in the southern USA in 1989 to 1993 was 8038 kg ha' 1 , compared with 8290 for Cypress, 7554 for Lemont, and 7699 for Maybelle. In the Louisiana Advanced Yield Tests (five locations) from 1990 to 1993, Jodon averaged overall yields of 8746 kg ha~', compared with 8502 for Cypress. In the Louisiana Commercial Cultivar Tests (four locations) from 1991 to 1993, Jodon averaged 8082 kg ha~' yields, compared with 7564,7063, and 6572 for Cypress, Lemont, and Maybelle, respectively. Jodon has displayed excellent ratoon-crop yields. In 12 experiments (1989-1993) from which ratoon data were obtained, Jodon averaged grain yields of 2878 kg ha~', compared with 2835 for Cypress. Ratoon-crop production is important in the rice production areas of southwest Louisiana and southeast Texas.