Evaluation of Injectable Sustained Release Progestin Formulations for Suppression of Estrus and Ovulation in Mares

Thirty-one mares were used in an experiment to evaluate the effectiveness of three sustained-release injectable formulations of altrenogest and one formulation of medroxyprogesterone acetate (MPA) for long-term suppression of estrus and ovulation. Luteolysis was induced by injection of prostaglandin-F_2α (Lutalyse) on day 0 (6th day after the previous ovulation) and was immediately followed by treatment with 1) no injection (controls; n = 7), 2) 1.5 mL of an altrenogest solution in sustained-release vehicle (LA 150, 1.5 mL; 225 mg altrenogest; n = 6), 3) 3 mL (450 mg altrenogest) of the same solution (n = 6), 4) 500 mg altrenogest in lactide-glycolide microparticles suspended in 7-mL vehicle (MP 500; n = 6), or 5) 1.0 g MPA as a 5-mL suspension. Mares were checked for estrus daily, and their ovaries scanned every other day until a 25-mm or greater follicle was detected, after which they were scanned daily. Control mares returned to estrus an average of 3.9 days after Lutalyse administration; all the single-injection altrenogest formulations increased (P < .05) the days to return to estrus, with the greatest increase occurring in mares receiving MP 500. Return to estrus was not affected by MPA treatment. Time of ovulation was determined by serial ultrasound scans and confirmed by daily plasma luteinizing hormone (LH) and progesterone concentrations. Control mares ovulated an average of 8.8 days after Lutalyse administration. Treatment with 1.5 or 3 mL of LA 150 increased (P < .05) the mean days to ovulation to 16.5 and 21.2 days, respectively; MP 500 increased (P < .05) the days to ovulation to 33.5 days. Administration of MPA did not affect (P > .1) days to ovulation relative to control mares. The MP 500 treatment provided long-term suppression of estrus and ovulation and could prove useful for that purpose. Treatment with the LA 150 solutions provided shorter-term suppression, and a relatively tight grouping of the individual mares around the mean days to ovulation; these one-shot formulations could be useful for synchronizing ovulation in cyclic mares and inducing normal estrous cyclicity in vernal transitional mares exhibiting erratic, anovulatory estrous periods.     

Experimental transmission of epizootic bovine abortion (foothill abortion)

Advances in defining the biology of epizootic bovine abortion (EBA), including identification of the etiologic agent, have been hampered by the inability to reproduce the disease with confidence. Experimental reproduction of EBA, by feeding the tick vector Ornithodoros coriaceus on susceptible pregnant heifers, is not reliable. The primary objectives of this study were to identify specific tissue(s) obtained from EBA-infected fetuses that could transmit the disease, and then utilize such an infectious challenge system to better define the pathogen, host immunity and geographic distribution of the agent. Described here is the ability to routinely reproduce EBA following inoculation of cryopreserved suspensions of homogenized thymus into susceptible pregnant heifers. This challenge system permitted experiments demonstrating the agent was non-filterable, inactivated upon sonication and susceptible to antibiotics. These findings suggest a prokaryotic microbe and represent a major advance in EBA research. Additional experiments demonstrated that inoculation of the cryopreserved EBA-infectious tissue into heifers, prior to breeding, conferred immunity. Furthermore, such immunized heifers were resistant to challenge with heterologous sources of infectious tissue, suggesting monovalent vaccine development might be feasible. Lastly, challenge studies employing animals from Central Nevada, an area considered free of EBA, demonstrated partial immunity, suggesting the pathogen, and possibly the disease, enjoy a broader distribution than previously thought.     

Regional Inventory of Organic Industrial Wastes: Case Study in New Brunswick,Canada

? This study was undertaken to investigate the possibility of composting organic industrial wastes which are currently being generated in the Canadian province of New Brunswick. Four types of this waste stream were identified: Fish wastes; Agricultural wastes; Pulp and paper and sawmill wastes; and Food processing wastes. Other objectives of this study were to establish valid cost estimates of selected solid waste composting approaches and to address the potential of a value-added compost product.

In the past 20 years, fish landings in the province averaged approximately 136,000 metric tons annually. Processing in fish transformation plants leads to fresh and pickled fish wastes that must be either discarded by dumping or processed into usable byproducts.

Animal manure is the principal waste currently being generated by the agricultural industry with 1,333,000 metric tons of manure produced in 1986. There are also approximately 90,000 metric tons of potato culls produced by the potato industry per year. Most of these agricultural wastes are presently being used or applied on land.

The forest industry is the biggest in New Brunswick and as such produces the largest amount of industrial wastes. Wood residues are generated in two sectors of the forest industry: Logging and Wood Processing organizations.

The food processing industry is a diversified enterprise processing items such as fruit products, vegetable products and meat products. Potato processing companies produce one of the most significant vegetable wastes of the province, with about 50,000 metric tons of wastes annually.     

Replacement of a Peat-Lite Medium with Compost For Cauliflower Transplant Production

Seedlings of ‘Candid Charm’ cauliflower (Brassica oleracea L. Botrytis group) were grown in six different media comprised of varying proportions of a commercial peat-lite mix (PL) and a 50% yard trimmings 50% biosolids compost. A control of 100% PL was compared to treatments of PL:compost at 80%:20%, 60%:40%, 40%:60%, and 20%:80% respectively by volume, and 100% compost. The experiment was performed twice. Electrical conductivity of the medium increased with increasing compost additions, while the carbon:nitrogen ratio was greatly decreased. Increasing proportions of compost blended with PL inconsistently affected medium pH. Seedling emergence was delayed when compost comprised the majority of the medium, but stands were not reduced except with 100% compost. Decreases in seedling height and dry weight began to occur in the 60% PL, 40% compost treatment and were more pronounced with higher amounts of compost. Seedlings grown in 80% PL, 20% compost were similar to those grown in 100% PL with one exception: the compost blend resulted in an increased seedling N concentration. While we cannot conclude that a 20% replacement rate is ideal, the 80% PL, 20% compost medium was horticulturally acceptable as an alternative to 100% PL for cauliflower transplant production.     

Role of water stress in differential aluminum tolerance of two barley cultivars grown in an acid soil

Two cultivars of barley (Hordeum vulgare L.), Al‐sensitive ‘Dayton’ and Al‐tolerant ‘Kearney’, were grown under controlled environmental conditions to determine the influence of Al stress and water stress imposed separately and in combination with one another. Plants were grown for 4 weeks in polyethylene‐lined, waxed cartons containing 1 kg of acid, Al‐toxic, Tatum subsoil (clayey, mixed, thermic, Typic Hapludult) at high (pH 4.7) or low (pH 6.6) Al stress. During the final 2 weeks they were also subjected to low (‐20 to ‐40 kPa) or high (‐60 to ‐80 kPa) water stress. Under low water stress, little difference in the growth or appearance of the two cultivars was found, even in the presence of low Al stress (pH 6.6). When high water stress treatment was superimposed on low Al stress treatment, however, significant differences between the two cultivars in biomass production, leaf enlargement, and tillering resulted. When high water stress was combined with high Al stress (pH 4.7), these differences in vegetative growth were further magnified. Thus, drought exacerbates the stress effects of Al toxicity in plants and may account for a significant portion of the reduction in yield commonly observed in acid soils under field conditions and formerly attributed to Al toxicity alone. By increasing soil moisture level, the growth suppressive effect of Al toxicity was significantly reduced.     

Role of water stress in differential aluminum tolerance of six sunflower cultivars grown in an acid soil

Six cultivars of sunflower (Helianthus annuus L.), were screened under controlled environmental conditions for tolerance to Al stress and water stress imposed separately and in combination with one another. Plants were grown for 4 weeks in waxed cartons containing 1 kg of acid, Al‐toxic Tatum, subsoil (clayey, mixed, thermic, Typic Hapludult) at high (pH 4.3) or low (pH 6.3) Al stress. During the final 2 weeks they were also subjected to low (‐20 to ‐40 kPa) or high (‐60 to ‐80 kPa) water stress. Plant growth responses and symptoms of Al toxicity suggested that a wide range of cultivar sensitivity existed. ‘Manchurian’, ‘S‐212’, ‘S‐254’, and ‘S‐265’ were relatively tolerant to Al toxicity while cultlvars ‘Romania HS‐52’ and ‘RM‐52’ were extremely sensitive. Under high Al stress and high water stress, chloroplasts in cells from the Al‐sensitive cultivar ‘Romania HS‐52’ were smaller and contained less starch than chloroplasts from the Al‐tolerant cultivar ‘Manchurian’. Furthermore, the smaller chloroplasts tended to have fewer grana stacks per unit area than did the chloroplasts from tolerant plants. These differences were not apparent when the Al‐sensitive cultivar was grown either in the absence of Al or water stress. In general, Al‐sensitive cultivars of sunflower were more tolerant to water stress than were Al‐tolerant cultivars. Increasing the soil moisture level reduced Al toxicity in Al‐sensitive cultivars. Similarly, decreasing Al stress partially overcame the detrimental effects of high water stress. Hence, Al stress and water stress are interrelated factors which must be considered in the characterization and breeding of plants for better adaptation to acid soils.     

Effect of saline irrigation water composition on selenium accumulation by wheat

Abstract

Trace amounts of selenium (Se) are essential for animal and human nutrition. However, the optimum concentration range is very narrow and outside of this range deficiencies or toxicities can occur. Potentially harmful levels of Se in soils and irrigation waters have been reported in regions where salinity is also a hazard. This study was conducted to determine the effects of irrigation water composition and salinity level on Se accumulation in leaves and grain of spring wheat (Triticum aestivum L. cv. ‘Yecora Rojo'). Plants were grown in greenhouse sand cultures and irrigated with complete nutrient solution. Salinity treatments were initiated 4 days after planting by irrigating the seedlings with either chloride‐dominated waters or with waters containing both chloride and sulfate salts. Compositions of the mixed salt waters were designed to simulate saline drainage waters commonly present in the San Joaquin Valley of California. The experimental design was a randomized complete block with two salinity types (Cl^? or mixed salts), eight salinity levels (osmotic potentials=0.07, 0.16, 0.21,0.30.0.36, 0.44, 0.52, and 0.63 MPa), and three replications. Four weeks after planting, Se (1 mg L^?1 as sodium selenate) was added to all irrigation waters. In the chloride system, the molar ratio of SO₄ ^2‐:SeO₄ ^2‐ was approximately 110 across all salinity levels, whereas in the mixed salt system, the SO₄ ^2‐ SeO₄ ^2‐ratio in solution increased from about 300 to 4,700 as salinity increased. Selenium concentration was determined in fully‐expanded flag leaf blades and grain. Salinity type, and to a lesser extent, salinity affected Se accumulation. In the Cl‐system, wheat accumulated Se to levels that may be potentially harmful to livestock and humans, e.g., blade‐Se ranged from 435 to 295 mg kg^?1 dry wt; grain‐Se ranged from 81 to 54 mg kg^?1 dry wt. Under the saline conditions of the mixed salt system, the inhibition of selenium uptake by sulfate reduced both blade‐ and grain‐Se to levels that would minimize the health risk to consumers.