Evidence of dependence between crop vigor and yield

A recent paper in Precision Agriculture concluded that algorithms to calculate in-season fertilizer nitrogen (N) recommendations need to include yield and fertilizer response considerations because grain yield and yield response index are independent of each other. The authors used maximum and zero N yields from selected long-term wheat and maize studies to support their conclusion. Yields from plots receiving intermediate N rates in the maize study indicated a probable dependence between grain yield and yield response index, which is contrary to the authors’ conclusions. Data from a more recent, long-term irrigated maize study on a similar soil type were used to illustrate that grain yield and yield response index are definitely dependent on each other and further that the in-season sensor-based sufficiency index is highly correlated with relative yield. The implication is that a yield component, as such, does not necessarily need to be included in development of an in-season N recommendation algorithm.     

Effects of dietary energy density and supplemental rumen undegradable protein on intake,viscera, and carcass composition of lambs recovering from nutritional restriction

Variation in nutrition is a key determinant of growth, body composition, and the ability of animals to perform to their genetic potential. Depending on the quality of feed available, animals may be able to overcome negative effects of prior nutritional restriction, increasing intake and rates of tissue gain, but full compensation may not occur. A 2 × 3 × 4 factorial serial slaughter study was conducted to examine the effects of prior nutritional restriction, dietary energy density, and supplemental rumen undegradable protein (RUP) on intake, growth, and body composition of lambs. After an initial slaughter (n = 8), 124 4-mo-old Merino cross wethers (28.4 ± 1.8 kg) were assigned to either restricted (LO, 500 g/d) or unrestricted (HI, 1500 g/d) intake of lucerne and oat pellets. After 8 wk, eight lambs/group were slaughtered and tissue weights and chemical composition were measured. Remaining lambs were randomly assigned to a factorial combination of dietary energy density (7.8, 9.2, and 10.7 MJ/kg DM) and supplemental RUP (0, 30, 60, and 90 g/d) and fed ad libitum for a 12- to 13-wk experimental period before slaughter and analysis. By week 3 of the experimental period, lambs fed the same level of energy had similar DMI (g/d) and MEI (MJ/d) (P > 0.05), regardless of prior level of nutrition. Restricted-refed (LO) lambs had higher rates of fat and protein gain than HI lambs (P < 0.05) but had similar visceral masses (P > 0.05). However, LO lambs were lighter and leaner at slaughter, with proportionally larger rumens and livers (P < 0.05). Tissue masses increased with increasing dietary energy density, as did DMI, energy and nitrogen (N) retention (% intake), and rates of protein and fat gain (P < 0.05). The liver increased proportionally with increasing dietary energy density and RUP (P < 0.05), but rumen size decreased relative to the empty body as dietary energy density increased (P < 0.05) and did not respond to RUP (P > 0.05). Fat deposition was greatest in lambs fed 60 g/d supplemental RUP (P < 0.05). However, lambs fed 90 g/d were as lean as lambs that did not receive supplement (P0, P > 0.05), with poorer nitrogen retention and proportionally heavier livers than P0 lambs (P < 0.05). In general, visceral protein was the first tissue to respond to increased intake during refeeding, followed by non-visceral protein and fat, highlighting the influence of differences in tissue response over time on animal performance and body composition.     

Ultrasonographic appearance and abdominal haemorrhage associated with a juvenile granulosa cell tumour in a foal

Granulosa cell tumours are commonly identified in mares, but have rarely been identified in equine neonates. This report describes a septic neonatal foal that presented with haemoabdomen secondary to a ruptured ovarian granulosa cell tumour. The ultrasonographic appearance, successful surgical removal and histopathological appearance of the tumour is described. Juvenile ovarian granulosa cell tumours differ histologically from adult granulosa cell tumours. Ultrasound is a useful way to identify haemoabdomen and abdominal masses in foals. Juvenile granulosa cell tumour should be considered as a differential for this combination in neonatal foals.     

Assessment of the economic costs of damage caused by air-pollution

Cost-benefit analysis is one of the fundamental tools for the development of economic instruments for pollution control. The costs of various abatement measures are reasonably well characterised. However, assessment of the economic costs of pollutant impacts is less well developed. This paper reports on two studies carried out for DGXII of the European Commission, the ExternE-Project and the Green Accounting Research Project. Both studies have been performed by international, multi-disciplinary research teams.Analysis of the effects of emissions of PM₁₀, SO₂, NO_x and VOCs (as ozone precursors) has included assessment of human health, materials, crops and other terrestrial ecosystems, and freshwater fisheries. The analysis follows the impact pathway approach, linking dose-response functions, valuation data and other models. It differs significantly to earlier top-down approaches that made only very limited use of the wealth of scientific data available. Most success has been achieved in analysis of impacts on human health, building materials and crops. Significant uncertainties exist for these receptors, though these have been identified and are now being addressed. Assessment of impacts on other receptors, perhaps most notably forests, is more limited. The methodology is particularly applicable for analysis of impacts on receptors for which the critical loads approach is not appropriate.     

Spatio-temporal modeling of fine particulate matter

Studies indicate that even short-term exposure to high concentrations of fine atmospheric particulate matter (PM_2.5) can lead to long-term health effects. In this article, we propose a random effects model for PM_2.5 concentrations. In particular, we anticipate urban/rural differences with regard to both mean levels and variability. Hence we introduce two random effects components, one for rural or background levels and the other as a supplement for urban areas. These are specified in the form of spatio-temporal processes. Weighting these processes through a population density surface results in nonstationarity in space. We analyze daily PM_2.5 concentrations in three midwestern U.S. states for the year 2001. A fully Bayesian model is implemented, using MCMC techniques, which enables full inference with regard to process unknowns as well as predictions in time and space.     

Liquid chromatographic determination of chlortetracycline hydrochloride in ruminant and poultry/swine feeds.

A liquid chromatographic (LC) method is described for the determination of chlortetracycline hydrochloride (CTC) in poultry/swine and ruminant feeds in the 10-100 ppm range and in premix. CTC is extracted from ground feed/premix with acidified acetone, and the extract is filtered through a Millex-HV filter or disposable C18 column. The filtrate is partitioned with methylene chloride when additional cleanup is necessary. A Nova-Pak C18 column is used for LC separation with determination at 370 nm. The average recovery of CTC from premix was 95% with a standard deviation (SD) of 1.70 and a coefficient of variation (CV) of 1.79%. The overall average recovery from feeds was 77% with an SD of 3.18 and a CV of 4.10%.     

Intraarticular injection of a Tin‐117 m radiosynoviorthesis agent in normal canine elbows causes no adverse effects

This longitudinal prospective exploratory study used serial measurements in five dogs to evaluate safety and retention of a tin‐117 m (^117mSn) colloid after intra‐articular injection in normal elbow joints. Each dog was deemed healthy based on physical examination, laboratory results, and radiographic evaluation of both elbows. While anesthetized, each received an MRI of both elbows, followed by fluorine‐18 fluorodeoxyglucose positron emission tomography scans of both elbow joints and associated lymph nodes. Joint fluid (0.5‐1.0 mL) was withdrawn aseptically from the left elbow joint, followed by intra‐articular injection of ^117mSn colloid (92.5 MBq; 1‐1.5 ml). Post‐injection assessments included blood counts, serum chemistry panels, urinalyses, radiographs, joint fluid analyses, MRI/positron emission tomography scans, scintigraphy, and biodistribution scans. On day 45‐47, each dog was euthanized and a complete postmortem examination was performed. Tissue samples were submitted for histopathology and radioisotope retention studies. Left elbow joints were decalcified and sectioned for future autoradiography. Scintigraphy, 1 day after injection, indicated slight radioisotope escape from the joint to regional lymph nodes. Serial blood, urine, feces, and organ counts indicated >99.1% of the ^117mSn activity was retained in the joint for 45‐47 days. Radiation output levels were below patient release levels the day following injection. Maximum standard uptake value for the injected joint decreased. Joint fluid cytology was unchanged. No dog exhibited lameness during the study. Absence of joint damage and lack of systemic effects after injection of the ^117mSn colloid in normal canine elbow joints indicate that this agent may be safely used for radiosynoviorthesis in dogs with osteoarthritis.     

Postsynaptic transmission block can cause terminal sprouting of a motor nerve

Sprouting of mouse soleus motor nerve terminals can be evoked by daily intramuscular injections of purified alpha-bungarotoxin. This finding supports the hypothesis that an important stimulus to terminal sprouting in partial denervation and presynaptic nerve blockade is a product of inactive muscle fibers.     

Detection of feline herpesvirus 1 DNA in skin biopsy specimens from cats with or without dermatitis

OBJECTIVE: To compare detection rates of feline herpesvirus 1 (FHV-1) DNA in skin biopsy specimens from cats with herpetic dermatitis, cats with nonherpetic dermatitis, and cats without dermatitis. DESIGN: Prevalence survey. Animals-5 cats (9 biopsy specimens) with herpetic ulcerative dermatitis, 14 cats (17 biopsy specimens) with nonherpetic ulcerative dermatitis, and 8 cats (21 biopsy specimens) without clinically apparent skin lesions. PROCEDURES: A single-phase PCR assay was used to detect FHV-1 DNA in biopsy specimens. Assay results were compared with results of histologic examination. RESULTS: FHV-1 DNA was detected in all 9 biopsy specimens from the 5 cats with herpetic dermatitis and in 1 of 17 biopsy specimens from the 14 cats with nonherpetic dermatitis, but was not detected in any of the 21 biopsy specimens from the 8 cats without dermatitis. When results of histologic examination were used as the gold standard, sensitivity and specificity of the PCR assay were 100% and 95%, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Results confirmed that FHV-1 DNA can be detected in the skin of cats with herpetic dermatitis and suggest that the virus may play a causative role in the disease. In addition, the PCR assay may be useful in confirming a diagnosis of herpetic dermatitis.     

Effect of different grazing management systems on the herbage mass and pasture height of a Nardus stricta grassland in western Scotland, United Kingdom

The aims of this study were to examine the effect of three grazing treatments (year‐round stocking rates of 0·8 ewes ha^?1, 0·5 ewes ha^?1 and 0·5 ewes ha^?1 plus grazing cattle in summer), imposed for 4 years, on the herbage mass and surface height of a Nardus stricta‐dominated grassland in western Scotland and to obtain estimates of annual productivity of this grassland. Nardus stricta‐dominated grassland comprised proportionately 0·20 of the grazing area. Stocking rate of sheep had no significant effect on the herbage mass of the grassland in the first 2 years of the experiment, although mean summer pasture heights were significantly higher under the lower stocking rate of sheep. The pasture on the treatment with cattle grazing in summer had a significantly lower herbage mass and lower surface height than the two sheep‐only grazing treatments. Year‐to‐year variation in the herbage mass and surface height of herbage in summer was greater than the effect of treatments. Despite changes in surface height, the structural diversity of the grasslands was not increased by the treatments. The annual production of vascular plant material ranged from 417 g DM m^?2 in 1994 to 628 g DM m^?2 in 1996.