Assessment of repeated application of poultry litter on phosphorus and nitrogen dynamics in loblolly pine: Implications for water quality

The Southeastern United States has a robust broiler industry that generates substantial quantities of poultry litter as waste. It has historically been applied to pastures close to poultry production facilities, but pollution of watersheds with litter-derived phosphorus and to a lesser extent nitrogen have led to voluntary and in some areas regulatory restrictions on application rates to pastures. Loblolly pine (Pinus taeda L.) forests are often located in close proximity to broiler production facilities, and these forests often benefit from improved nutrition. Accordingly, loblolly pine forests may serve as alternative land for litter application. However, information on the influence of repeated litter applications on loblolly pine forest N and P dynamics is lacking. Results from three individual ongoing studies were summarized to understand the effects of repeated litter applications, litter application rates, and land use types (loblolly pine forest and pasture) on N and P dynamics in soil and soil water. Each individual study was established at one of three locations in the Western Gulf Coastal Plain region. Annual applications of poultry litter increased soil test P accumulation of surface soils in all three studies, and the magnitude of increase was positively and linearly correlated with application rates and frequencies. In one study that was established at a site with relatively high soil test P concentrations prior to poultry litter application, five annual litter applications of 5 Mg ha⁻¹ and 20 Mg ha⁻¹ also increased soil test P accumulation in subsurface soils to a depth of up to 45 cm. Soil test P accumulations were greater in surface soils of loblolly pine stands than in pastures when both land use types received similar rates of litter application. In one study which monitored N dynamics, lower soil organic N, potential net N mineralization, potential net nitrification, and soil water N was found in loblolly pine stands than pastures after two annual litter applications. However, increases in potential net N mineralization, net nitrification, and soil water N with litter application were more pronounced in loblolly pine than in pasture soils. Loblolly pine plantations can be a viable land use alternative to pastures for poultry litter application, but litter application rate and frequency as well as differences in nutrient cycling dynamics between pine plantations and pastures are important considerations for environmentally sound nutrient management decisions.     

Fitness costs associated with infections of secondary endosymbionts in the cassava whitefly species <Emphasis Type="Italic">Bemisia tabaci</Emphasis>

We investigated the dual effects of bacterial infections and diseased cassava plants on the fitness and biology of the Bemisia tabaci infesting cassava in Africa. Isofemale B. tabaci colonies of sub-Saharan Africa 1-subgroup 3 (SSA1-SG3), infected with two secondary endosymbiotic bacteria Arsenophonus and Rickettsia (AR+) and those free of AR infections (AR?), were compared for fitness parameters on healthy and East African cassava mosaic virus-Uganda variant (EACMV-UG)-infected cassava plants. The whitefly fecundity and nymph development was not affected by bacterial infections or the infection of cassava by the virus. However, emergence of adults from nymphs was 50 and 17% higher by AR? on healthy and virus-infected plants, respectively, than AR+ flies. Development time of adults also was 10 days longer in AR+ than AR?. The whiteflies were further compared for acquisition and retention of EACMV-UG. Higher proportion of AR? acquired (91.8%) and retained (87.6%) the virus than AR+ (71.8, 61.2%, respectively). Similarly, the AR? flies retained higher quantities of virus (~ninefold more) than AR+. These results indicated that bacteria-free whiteflies were superior and better transmitters of EACMV-UG, as they had higher adult emergence, quicker life cycle and better virus retention abilities than those infected with bacteria.     

Organic matter inputs into headwater streams of southwestern British Columbia as a function of riparian reserves and time since harvesting

Riparian vegetation strongly influences the structure and function of terrestrial and aquatic ecosystems; therefore, harvest of riparian trees can profoundly impact these habitats. Riparian reserves (no harvest zones) are used world-wide to reduce these impacts, including effects on organic matter dynamics. There are, however, few experimental evaluations of their efficacy. Particulate organic matter delivery from riparian vegetation to streams, a critical ecosystem process, was measured over an eight year period after logging in southwestern British Columbia, Canada to quantify the relationship between these litter fluxes and riparian reserves (unlogged controls, 30 and 10-m wide uncut reserves, and clear-cuts). We hypothesized that the timing, composition and quantity of organic matter entering these streams would vary as a function of reserve width, but that these differences would decline with time since logging. We also hypothesized that inter-annual variation in precipitation patterns would partially contribute to litter dynamics. Riparian treatment significantly affected the quantity and composition of litter flux: inputs of needles and twigs were significantly lower and proportion of deciduous litter higher in clear-cut streams compared to other treatments. ANOVA models indicated that treatment differences in litter flux persisted through year 7 for some components of litter, while regression models indicated positive trends between reserve width and litter flux through year 8. This positive slope indicates the clear-cut treatment had yet to recover from logging. Variation in snowfall and plant succession contributed to temporal variation in litter flux; in some cases, litter inputs increased with annual snowfall. Another key finding from this study was that riparian reserves provided total litter inputs to streams that were similar to fully forested controls.     

A pilot study on ethanol-polyethylene glycol-formalin fixation of farm animal cadavers

Most embalming of cadavers for anatomical dissection in veterinary medicine has used 6-10% formaldehyde resulting in discoloured and rigid specimens. This project produced teaching specimens of sheep, horse and calf cadavers having their musculoskeletal and visceral structures with a natural appearance using a fixation solution with lowered concentrations of formaldehyde (2% and 3%) together with ethanol and polyethylene glycols. Fixation parameters (palpable consistency, flexibility, colour, tissue hydration and odour) were assessed qualitatively by twice weekly dissections over two months for sheep and three months for horses and calf. Formaldehyde levels, measured in the breathing zone, were below the maximum allowable concentration in all specimens except for a 300 kg horse cadaver. To evaluate the effectiveness of the fixation solution in microbial inhibition, tissue samples were taken and analyzed for the presence of culturable aerobic and anaerobic bacteria, yeasts and moulds. Single colonies of Pseudomonas oryzihabitans, Chryseobacterium sp., Acinetobacter sp. were isolated from lungs, and Micrococcus sp. and Bacillus sp. were isolated from one muscle sample.     

Potato tuber sugar content during development and storage (10°C): possible predictors of storage potential and the role of sucrose in storage hexose accumulation

Summary Reducing sugar and sucrose contents of potato tubers (Solanum tuberosum L.) from six cultivars were monitored both during the growing season and after a four months storage period at 10°C. Significant correlations were found between tuber sugar contents (sucrose, reducing and total) measured at harvest and the reducing sugar content after storage. Similarly, in five of the six cultivars, the sucrose loss and the corresponding reducing sugar gain during storage were significantly correlated.     

Standing laparoscopic-guided uterine biopsy in a southern white rhinoceros (Ceratotherium simum simum).

Transrectal ultrasonography of a 35-yr-old captive female southern white rhinoceros (Ceratotherium simum simum) with a history of chronic mucohemorrhagic vulvar discharge revealed right transmural uterine horn enlargement. Abdominal laparoscopic surgery, although extremely difficult because of inadequate instrumentation, permitted uterine visualization and biopsy. Standing anesthesia, incorporating butorphanol and azaperone together with local anesthetic infiltration, facilitated the laparoscopy. A leiomyoma was suspected on the basis of history, physical examination, ultrasonographic appearance, and histopathology. Prior rhinoceros laparoscopies have failed, primarily from limitations imposed by recumbency.     

Subsequent reproduction and calf performance of nonpregnant cows compared with pregnant cows and replacement females

This study was conducted with Angus, Polled Hereford and Santa Gertrudis straightbred and crossbred cows. The subsequent cow breeding and calf performance of cows that were nonpregnant (NP) were compared with cows that were pregnant (PG) at the time calves were weaned. All NP cows had a calf the year previous to their being nonpregnant. They were diagnosed as physically sound with no detection (by rectal palpation) of an abnormal reproductive tract. The NP and PG cows were aged 4 to 9 yr. Also, the NP cows were compared with replacement females exposed to calve first as 2- and 3-yr-olds (H2 and H3, respectively), and with cows exposed for second calving as 3-yr-olds (C2). Cows were assigned within breed composition and age to sire breeding groups on pasture. Subsequent calving and weaning rates were similar for NP, PG and H2 cows, similar for H3 and H2 cows and lowest (P less than .05) for C2 cows. Calves from NP and H3 cows were born earlier (P less than .05) in the calving period than calves from PG and H2 cows, whereas calves from C2 cows were born later (P less than .05) than those from NP, PG and H3 cows. Calving difficulty was similar for NP, PG and C2 and greatest (P less than .05) for H2 cows. Calf 205-d weights were highest (P less than .05) for NP, similar for PG and H3 and lowest (P less than .05) for C2 and H2 cows. Calf weaning weight per cow exposed for breeding from NP cows was 13.8, 32.3, 55.2 and 1.0 kg higher than from PG, H2, C2 and H3 cows, respectively. Causes for cows being nonpregnant were reported. Also, calving patterns during 6 consecutive calving periods (6 yr) were evaluated.