Pros and cons of using alpha-2 agonists in small animal anesthesia practice

The alpha-2 agonists have been used in veterinary practice for over 30 years following the introduction of xylazine (ROMPUN, Bayer Corp., Shawnee Mission, KS) in 1962. The decision to use alpha-2 agonists in anesthesia practice should be based on factors including patient disposition, presenting complaint, type of procedure, and the veterinarian's familiarity with the drug. Controversy surrounds the issue of using anticholinergic agents concurrent with the alpha-2 agonists. Patient selection and procedure type can aid in determining when use of an anticholinergic with the alpha-2 agonist is advantageous. Antagonism of alpha-2 agonists can be readily accomplished. Commonly, alpha-2 agonists are used in combination with other agents to provide neuroleptanalgesia or sedation prior to general anesthesia.     

Spatial and Temporal Dynamics of Stink Bugs in Southeastern Farmscapes

A 3-yr study (2009–2011) was conducted to examine the spatial and temporal dynamics of stink bugs in three commercial farmscapes. Study locations were replicated in South Carolina and Georgia, in an agriculturally diverse region known as the southeastern coastal plain. Crops included wheat, Triticum aestivum (L.), corn, Zea mays (L.), soybean, Glycine max (L.), cotton, Gossypium hirsutum (L.), and peanut, Arachis hypogaea (L.). Farmscapes were sampled weekly using whole-plant examinations for corn, with all other crops sampled using sweep nets. The predominant pest species of phytophagous stink bugs were the brown stink bug, Euschistus servus (Say), the green stink bug, Chinavia hilaris (Say), and the southern green stink bug, Nezara viridula (L.). Chi-square tests indicated a departure from a normal distribution in 77% of analyses of the variance to mean ratio, with 37% of slopes of Taylor’s power law and 30% of coefficient β of Iwao’s patchiness regression significantly greater than one, indicating aggregated distributions. Spatial Analyses by Distance IndicEs (SADIE) indicated aggregated patterns of stink bugs in 18% of year-end totals and 42% of weekly counts, with 80% of adults and nymphs positively associated using the SADIE association tool. Maximum stink bug densities in each crop occurred when the plants were producing fruit. Stink bugs exhibited greater densities in crops adjacent to soybean in Barnwell and Lee Counties compared with crops adjacent to corn or fallow areas. The diversity of crops and relatively small size of fields in the Southeast leads to colonization of patches within a farmscape. The ecological and management implications of the spatial and temporal distribution of stink bugs within farmscapes are discussed.     

Characterization of volatile compounds contributing to naturally occurring fruity fermented flavor in peanuts

Published research has indicated that ethyl 2-methylpropanoate, ethyl 2-methybutanaote, ethyl 3-methylbutanoate, hexanoic acid, butanoic acid, and 3-methylbutanoic acid are responsible for fruity fermented (FF) off-flavor; however, these compounds were identified in samples that were artificially created by curing immature peanuts at a constant high temperature. The objective of this study was to characterize the volatile compounds contributing to naturally occurring FF off-flavor. Volatile compounds of naturally occurring FF and no-FF samples were characterized using solvent-assisted flavor evaporation (SAFE), solid phase microextraction (SPME), gas chromatography-olfactometry (GC-O), and gas chromatography-mass spectrometry (GC-MS). Aroma extract dilution analysis (AEDA) identified 12 potent aroma active compounds, none of which were the previously identified esters, with no consistent differences among the aroma active compounds in no-FF and FF samples. Hexanoic acid alone was identified in the naturally occurring FF sample using the SAFE GC-MS methodology, whereas two of the three previously identified esters were identified in natural and artificially created samples. The same two esters were confirmed by SPME GC-MS in natural and artificially created samples. This study demonstrated the need for caution in the direct application of data from artificially created samples until those compounds are verified in natural samples. However, these results suggest that a laboratory method using SPME-GC techniques could be developed and correlated on an ester concentration versus FF intensity basis to provide an alternative to sensory analysis for detection of FF off-flavor in peanut lots.     

Genetic diversity and phenotypic variation for drought resistance in alfalfa (<Emphasis Type="Italic">Medicago sativa</Emphasis> L.) germplasm collected for drought tolerance

Drought is a major environmental factor hampering alfalfa productivity worldwide. Gene banks provide an array of trait diversity, frequently consisting of specific seed collection projects that focused on acquiring germplasm adapted to specific traits such as drought tolerance. These subsets provide a logical starting point to identify useful breeding resources. In the present study, we investigated the genetic diversity and evaluated 18 agronomic, physiological and quality traits associated with drought tolerance in a subset of 198 alfalfa accessions collected for their potential drought resistance. Significant differences were found among accessions for most of the traits evaluated. Water deficit significantly decreased biomass dry yield by 61.9% compared with well-watered control. A positive correlation was found between relative water content (RWC) and drought susceptible index, while negative correlations were found between RWC and leaf senescence (LS), and between RWC and canopy temperature (CT). Alfalfa accessions with high RWC showed relative lower yield reduction, cooler CT and delayed LS. Genetic variation for forage quality was also investigated and the correlation between agronomic and quality traits was analyzed. Biomass yield under drought was negatively correlated with total protein, relative feed value and relative forage quality, suggesting that the efforts to improve yield under drought tend to negatively affect forage quality. Therefore, maintaining forage quality should be considered for breeding alfalfa with drought resistance. Alfalfa accessions with high drought resistance scores and minimum loss of quality were identified in this study and can be used as genetic resources for developing alfalfa varieties with improved drought resistance and water use efficiency while maintaining forage quality.     

Semen Characteristics in a Sub‐Fertile Arabian Stallion with Idiopathic Teratospermia

A 5‐year‐old Arabian stallion was managed for breeding with fresh/extended semen during a period of 8 months with a resulting per cycle pregnancy rate of 26.3%. The stallion was in good health and no abnormalities of the reproductive tract were observed. Evaluation of several ejaculates revealed that sperm production and semen quality were mostly unchanged during the period of evaluation, that sperm production was normal and that semen quality was extremely poor. The most prevalent sperm defects were abnormal heads and mid‐pieces. Most abnormal heads were microcephalic and/or tapered and considerable variation in sperm head dimensions within and among ejaculates was observed. A unique defect characterized by swollen/roughened mid‐piece caused by accumulation of cytoplasmic‐like material and abnormal mitochondrial sheath was observed. Nuclear vacuoles, acrosome defects, and teratoids were also prevalent and most sperm presented multiple abnormalities. The absence of any clear cause or any signs of testicular degeneration, combined with normal sperm production, and constant abnormal sperm production suggest an inherent, congenital disturbance of spermatogenesis as the cause of teratospermia in this case.     

Influence of oscillating dietary crude protein concentration on performance, acid-base balance, and nitrogen excretion of steers

Decreasing dietary N inputs into beef cattle feeding operations could potentially decrease environmental concerns relating to air and water quality. Previous studies with sheep suggest that oscillating dietary CP concentrations may improve N use efficiency and thereby decrease dietary N requirements. Therefore, two studies were conducted to determine the effects of oscillating dietary CP concentrations on performance, acid-base balance, and manure characteristics of steers fed high-concentrate diets. Steers were fed to a constant backfat thickness in both studies. In the first trial, 92 steers (mean BW = 408 +/- 2.8 kg; four pens/treatment) were fed the following diets: 1) constant 12% CP, 2) constant 14% CP, and 3) 10 and 14% CP oscillated at 2-d intervals. Steer performance and carcass characteristics were measured. In the second trial, 27 steers were individually fed the same three experimental dietary regimens (nine steers/treatment). Animal performance, arterial acid-base balance, plasma metabolites, and fecal characteristics were measured. In both trials, steers fed the 14% CP diet tended (P < 0.10) to have greater ADG and gain:feed than steers fed the 12% CP diet. Steers fed the oscillating CP regimen had intermediate performance. In Trial 1, steers fed the 14% CP diet tended (P = 0.09) to have smaller longissimus area and higher quality grades than steers fed the oscillating CP regimen. Protein retentions (g/d) calculated from NRC (2000) equations were greater (P = 0.04) for steers fed the 14% CP diet than steers fed the 12% CP diet. Steers fed the oscillating CP regimen tended (P = 0.08) to have greater calculated protein retention (g/d) than steers fed the 12% CP diet. Steers fed the 14% CP diet had greater (P < 0.05) calculated urinary N excretion than steers fed the 12% CP or oscillating CP regimens. Venous plasma concentrations of urea N were greater (P < 0.001) in steers fed the 14% CP diet than in steers fed the 12% CP diet; steers fed the oscillating CP regimen were intermediate but fluctuated over days. Based on arterial blood gas concentrations, acid-base balance was not significantly affected by dietary CP regimen. Results of these trials suggest that the CP requirement of steers in these studies was greater than 12% of the diet DM, and/or that the degradable CP requirement was greater than 6.3% of diet DM. However, the effects of oscillating dietary CP were minimal.