Rearing conditions influence nutrient availability of plant extracts supplemented diets when fed to broiler chickens

The effects of a standardised mixture of essential oils, including 5% carvacrol, 3% cinnamaldehyde and 2% capsicum (XT 6930; Pancosma S.A), on dietary apparent metabolisable energy corrected for nitrogen retention (AMEn), nutrient digestibility and mucin secretions, measured as sialic acid (SA) were investigated in broilers fed on the same diet but reared under different conditions, that is, cages and floor pens littered with wood shavings used in previous broiler study. The use of XT reduced (p < 0.05) nitrogen digestibility (0.585 vs. 0.544) and tended (p = 0.072) to reduce dry matter digestibility (0.733 vs. 0.717) of the diet when fed to birds reared in cages. However, XT supplementation improved (p < 0.05) fat digestibility (0.844 vs. 0.862) and tended (p = 0.093) to increase AMEn (14.01 vs. 14.25 MJ/kg DM) of the same diet when fed to broilers reared in floor pens. Essential oils supplementation tended (p = 0.059) to increase the secretion of SA, when fed to birds reared in cages (11.24 vs. 14.18 μg), but did not influence (p > 0.05) the SA secretion from birds reared in floor pens. The results obtained from the cage study tend to be the opposite of those obtained from the floor pen study. This suggests that the efficiency of dietary plant extracts may be influenced by the rearing/hygienic conditions of poultry. Based on the overall results, it can be concluded that information on rearing conditions should be taken into account for more complete interpretation of the experimental data emanating from experiments involving use of essential oils typified by those considered in this study.     

Compensatory density dependence in fish populations: importance, controversy, understanding and prognosis

Density‐dependent processes such as growth, survival, reproduction and movement are compensatory if their rates change in response to variation in population density (or numbers) such that they result in a slowed population growth rate at high densities and promote a numerical increase of the population at low densities. Compensatory density dependence is important to fisheries management because it operates to offset the losses of individuals. While the concept of compensation is straightforward, it remains one of the most controversial issues in population dynamics. The difficulties arise when going from general concepts to specific populations. Compensation is usually quantified using some combination of spawner–recruit analysis, long‐term field monitoring or manipulative studies, and computer modelling. Problems arise because there are limitations to each of these approaches, and these limitations generally originate from the high uncertainty associated with field measurements. We offer a hierarchical approach to predicting and understanding compensation that ranges from the very general, using basic life‐history theory, to the highly site‐specific, using detailed population models. We analyse a spawner–recruit database to test the predictions about compensation and compensatory reserve that derive from a three‐endpoint life‐history framework designed for fish. We then summarise field examples of density dependence in specific processes. Selected long‐term field monitoring studies, manipulative studies and computer modelling examples are then highlighted that illustrate how density‐dependent processes led to compensatory responses at the population level. Some theoretical and empirical advances that offer hope for progress in the future on the compensation issue are discussed. We advocate an approach to compensation that involves process‐level understanding of the underlying mechanisms, life‐history theory, careful analysis of field data, and matrix and individual‐based modelling. There will always be debate if the quantification of compensation does not include some degree of understanding of the underlying mechanisms.     

Reduction in Microbial Load of Wheat by Tempering with Organic Acid and Saline Solutions

Reducing microbial contamination in wheat is desirable to ensure consumer safety. In this study, the efficacy of adding organic acids and NaCl to tempering water to reduce microbial contamination in hard wheat was evaluated. Hard red winter wheat was tempered to 15.5% moisture by adding sterile distilled water (control) or tempering solutions containing organic acids (acetic, citric, lactic, or propionic; 1.0, 2.5, or 5.0 v/v), NaCl (26 or 52% w/v), or a combination of organic acid (acetic or lactic; 2.5 and 5.0% v/v) and NaCl (26 or 52% w/v). After tempering, the microbial load was significantly reduced by all the acid and NaCl treatments when compared with the control. Wheat tempered with 5% acetic, propionic, and lactic acids resulted in reductions of 1.7, 2.3, and 3.8 log colony forming units (CFU) per gram in aerobic plate count (APC), Enterobacteriaceae (Eb), and mold counts, respectively. The combination lactic acid (5.0%) and NaCl (52%) was the most effective against APC and Eb, with an average reduction of 4.3 and 4.7 log CFU/g, respectively. Tempering wheat with organic acids and saline solutions may provide milled products with improved microbiological quality when compared with the traditional tempering process using water.     

A model incorporating the diffuse double layer to predict the electrical conductivity of bulk soil

A model has been developed to predict the electrical conductivity of bulk soil. The total soil-water content is divided into free water and water in the diffuse double layer (DDL) around clay particles. These two fractions of soil water conduct electrical current through the soil and are assumed to act in parallel with the soil solid. The volume of water in the DDL is evaluated from the surface area of the clay and the thickness of the DDL. The surface area of the clay is estimated from its cation exchange capacity (CEC) and surface charge density. A transmission coefficient correcting for the effect of the tortuous flow path of current through the soil, and a proportionality constant relating the electrical conductivity of water in the DDL to that of free water, are included in the model. The transmission coefficient is a function of the contents of water and clay and has been modelled in terms of these factors. The values of the proportionality constant and those relating to the transmission coefficient were optimized for five different soils. The electrical conductivities of the five soils estimated by the model compare well with the measured values, which, however, deviate systematically from predictions by the three-component model of Rhoades et al .     

Evaluation of tumescent local anesthesia in cats undergoing unilateral mastectomy

ObjectiveTo evaluate the analgesic efficacy and safety of tumescent local anesthesia (TLA) in cats undergoing unilateral mastectomy.Study designProspective clinical trial.AnimalsA total of 12 ovariohysterectomized female cats.MethodsAll animals were premedicated with pethidine (4 mg kg^–1) intramuscularly (IM), followed by induction of anesthesia with propofol (5 mg kg^–1) intravenously and maintenance with isoflurane in oxygen. A refrigerated TLA solution (15 mL kg^–1, 8 °C) was injected using a Klein cannula. The solution was composed of 0.5 mL of epinephrine (1 mg mL^–1) and 40 mL of 2% lidocaine added to 210 mL lactated Ringer’s solution (final lidocaine concentration 0.32%). Heart and respiratory rates, systolic arterial blood pressure, temperature and oxygen saturation were measured during anesthesia. Blood samples were collected from the jugular vein for measurement of plasma lidocaine concentration using high performance liquid chromatography. Postoperative pain scores were evaluated hourly for 6 hours. Analgesic rescue was performed with tramadol (2 mg kg^–1) IM and meloxicam (0.15 mg kg^–1) subcutaneously.ResultsPlasma lidocaine concentration peaked at 90 minutes after injection of TLA, but no concentration considered toxic for the species was measured. The median postoperative analgesia time was 6 hours after injection of TLA.ConclusionsThis study found that TLA prevented sympathetic response to noxious stimuli during anesthesia and provided satisfactory postoperative analgesia in cats submitted to total unilateral mastectomy, with no apparent signs of toxicity.Clinical relevanceTLA can prevent sympathetic stimulation resulting from noxious stimuli during anesthesia, promoting good intraoperative conditions, proving to be a viable addition to analgesia in cats submitted to a total unilateral mastectomy.     

Bone morphogenetic protein 15 supplementation enhances cumulus expansion,nuclear maturation and progesterone production of in vitro-matured bovine cumulus-oocyte complexes

In vitro embryo production (IVP) efficiency is reduced when compared to in vivo. The basic knowledge of bovine in vitro oocyte maturation (IVM) mechanisms provides support to improve in vitro embryo production yields. The present study assessed the effects of bone morphogenetic protein 15 (BMP15), fibroblast growth factor 16 (FGF16) and their combined action on cumulus cells (CC) expansion, oocyte and CC DNA fragmentation, oocyte nuclear maturation, energetic metabolism and progesterone production in bovine IVM. Cumulus-oocyte complexes (COC) were matured in control or supplemented media containing BMP15 (100 ng/ml), FGF16 (10 ng/ml) or BMP15 combined with FGF16; and assessed at 0 and 22 hr of IVM. BMP15 alone or its association with FGF16 enhanced cumulus expansion. BMP15 decreased DNA fragmentation in both CC and oocytes, and improved oocyte nuclear maturation rate. In addition, BMP15 increased CC progesterone production, an effect not previously reported. The present study reinforces previous data pointing to a beneficial influence of BMP15 during IVM, while providing novel evidence that the underlying mechanisms involve increased progesterone production.     

Biooxidation of added and natural hydrocarbons in soils: Effect of iron

The decomposition of pure hydrocarbons in soils depends essentially on the intrinsic biological activity of the soils. Seasonal variations were observed, but other environmental factors, such as acidity, were more important. In non-acid soils, the structure of the hydrocarbons was secondary, whereas in acid soils, the rate of decomposition was much slower and depended on their chain length. The difference was reflected, in characteristic soils, in the natural distribution of the hydrocarbons, which originate predominantly from plant decay.Two acid soils, supplemented with ferric hydroxide, were incubated for 16 weeks at 28°C and their hydrocarbon fraction analyzed. Iron enrichment did not lead to complete biodegradation but rather to stimulation of the biooxidation of unbound hydrocarbons and to disppearance of the chain length discrimination. Conversely, the bound alkanes were stable towards microbial activity, with only the amounts of short chain hydrocarbons being slightly reduced.     

Dissipation of Cotton Pesticides from Runoff Water in Glasshouse Columns

The use of vegetated wetlands for accelerating pesticide removal from agricultural runoff is gaining acceptance as a best management practice. In this study, the dissipation of five cotton pesticides – endosulfan, chlorpyrifos, aldicarb, prometryn and diuron – was quantified in cotton field runoff water contained in glasshouse columns, under light or dark conditions. Two water samples sourced from large, non-vegetated storage dams were compared with two other water samples obtained from vegetated wetlands receiving runoff from cotton fields. All pesticides studied except chlorpyrifos dissipated significantly faster from the storage dam samples than the vegetated wetland samples. Suggested reasons include a greater number of pesticide-degrading microorganisms in the storage dam waters and/or the presence of more organic matter in the wetland samples, limiting contaminant volatilisation and hydrolysis. Exposure to light significantly reduced the rate of endosulfan removal, whereas light increased the rate of chlorpyrifos removal. Half-lives are presented for each pesticide where appropriate.     

Soil water stress: Its effects on phenology, physiology, and morphology of containerized Douglas-fir seedlings

Containerized Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) seedlings were subjected to six moisture-stress treatments (ranging from 7 to 65% soil water content by volume) for 12 weeks. At the end of this period, there were significant differences in phenological, physiological, and morphological responses among the seedlings in the various moisture-stress treatments. In general, seedlings grown under very high or very low soil moisture conditions were adversely affected, while those grown under moderate conditions (29 to 53% soil water content) exhibited optimum growth, bud development, and nutrient and starch reserves. The use of vector analysis was found to be helpful in data interpretation. The results indicate the importance of closely monitoring nursery moisture regimes in order to achieve the best seedling quality.