The intensity of resistance by mature Merino ewes against Haemonchus contortus and Tichostrongylus colubriformis in single-species and combined-species infection

Three-year-old, non-lactating and non-pregnant Merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with Haemonchus contortus, were given single-dose infections with either H. contortus or Trichostrongylus colubriformis or both species together. The purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to infection. To provide a criterion, some infected ewes were immunosuppressed with corticosteroid, dexamethasone. Untreated ewes were extremely resistant to challenge infection with either 15,000 or 150,000 H. contortus or 15,000 T. colubriformis. Surprisingly, when mixed infection was given, egg counts for H. contortus were significantly elevated compared with infection by that species alone. Antibody to antigens from infective larval and adult H. contortus was measured in serum by enzyme-linked-immunosorbent assay (ELISA) during the course of infection. Serum titres against larval antigens were significantly depressed when infections with either H. contortus or T. colubriformis were permitted by immunosuppression with dexamethasone, whereas those against adult antigen were depressed when infection with T. colubriformis was permitted.     

Soil CO2 emission in sugarcane management systems

Sugarcane management systems affect soil attributes such as the carbon cycle. This fact has stimulated the sugar and alcohol industry to refine the sugarcane production systems by replacing the pre-harvest burning (PB) and manual harvest with mechanized harvesting followed by residue deposition. The aim of this study was to evaluate different management systems with respect to C cycling carbon dioxide and soil parameters (chemical, physical and biological) which were determined over the season. Three sugarcane cultivation systems were evaluated at the following periods: (a) PB, (b) 5-year green harvest and (c) 10-year green harvest. The results indicated that CO₂ emission was 36% greater in the 10-year sugarcane green harvest system than in the PB system. The bulk density and macroporosity were the factors that were most affected by the different sugarcane management systems and that significantly influenced soil CO₂ emissions. The principal component analysis showed that soil CO₂ emission was 18% influenced by base saturation (V%) and 14% by pH, especially in the PB area. Additionally, 19% was affected by carbon and macroporosity in the 5- and 10-year green harvest areas, respectively. From our results, it can be concluded that the most CO₂ emissions are in the areas of sugarcane green, this is due to the higher carbon concentration when compared with the area of burning sugarcane. The parameters that most influenced the CO₂ emissions were bulk density, porosity, macroporosity, pH and V%.     

Establishment techniques affect productivity,nutritive value and atmospheric N2 fixation of two sunn hemp cultivars

Nitrogen fertilization is a common practice for sustaining forage production in forage systems in southeastern United States. Warm-season annual legumes may be an alternative forage to warm-season perennial grasses that do not require N fertilization. Sunn hemp (Crotalaria juncea L.) is a fast-growing, warm-season annual legume native to India and Pakistan. The objective of this 2-year study was to assess the herbage accumulation (HA), atmospheric N₂ fixation (ANF) and nutritive value of sunn hemp. Treatments were the factorial arrangement of two sunn hemp cultivars (“Crescent Sun” and “Blue Leaf”), three seeding rates (17, 28 and 39 kg seed/ha) and seed inoculation (inoculated or non-inoculated seeds), distributed in a randomized complete block design with four replicates. Crescent sun had greater HA (3,218 vs. 1764 kg DM/ha) and ANF (41 vs. 25 kg N/ha). Blue leaf had greater crude protein (CP) (188 vs. 176 g/kg) and in vitro digestible organic matter (IVDOM) concentrations (564 vs. 531 g/kg) than crescent sun. Non-inoculated seed had greater CP than inoculated seed, 188 and 177 g/kg, respectively, and inoculation did not affect HA. Intermediate seeding rate (28 kg/ha) decreased HA (2002 kg DM/ha), while HA from high and low seeding rates (17 and 39 kg/ha, respectively) did not differ (2,863 and 2,615 kg DM/ha respectively). Planting non-inoculated crescent sun at 17 kg/ha seeding rate is a feasible management practice to produce sunn hemp in subtropical regions; however, inoculation should always be recommended for proper establishment.     

Near-Infrared Spectroscopy Coupled with Chemometrics Tools: A Rapid and Non-Destructive Alternative on Soil Evaluation

Near-infrared (NIR) spectroscopy is a rapid, non-destructive and accurate technique for analyzing a wide variety of samples, thus, the growing interest of using this technique in soil science. The objective of this study was to evaluate the potential of NIR spectroscopy to predict organic carbon (OC), total nitrogen (TN), available phosphorus (P) and available potassium (K) in the soil. NIR spectra from 20 cm³ of soil samples were acquired on the range of 750 to 2500 nm in diffuse reflectance mode, resolution of 16 cm^?1 and 64 scans. Eight models of calibration/validation were constructed. Calibration and validation models showed that the predictive potential of NIR varied with the specific soil property (OC, TN, P and K) under evaluation and according to the methodology employed in the model construction (cross-validation or test set). Good prediction models were obtained for OC and TN content based on the statistical parameters. Test set methodology was able to predict soil OC, TN, P, and K better than cross-validation methodology.     

First molecular detection of canine herpesvirus 1 (CaHV-1) in the Eastern Brazilian Amazon

BackgroundCanine herpesvirus type 1 (CaHV-1) infects dogs and is associated with neonatal deaths and reproductive, ocular, neurological, and respiratory problems. In Brazil, reports of CaHV-1 have been restricted to the southeast and south regions, particularly in municipalities in the state of Rio Grande do Sul.ObjectivesTo assess the presence and variability of CaHV-1 in canine populations in the state of Pará, North Brazil.MethodsBiological samples from 159 dogs from 4 municipalities in the State of Pará were evaluated using polymerase chain reaction and phylogenetic analyses, with the target being the viral enzyme, thymidine kinase.ResultsCaHV-1 was detected in 13 dogs (8.2%), with 2 animals being from the municipality of Santa Bárbara do Pará, 8 from Algodoal Island, 2 from Salinópolis, and one from Capanema. The study sequences revealed 100% identity among themselves and 64% to 100% identity with the other nucleotide sequences from Australia, Brazil, United Kingdom, and United States, including 100% identity with the 2002 isolate from Australia. The 1996 isolate from France was grouped in a branch that was different from the sequence of this study.ConclusionsThis study presents the first molecular detection of CaHV-1 in dogs from the Amazon region in northern Brazil. The nucleotide identity between the strains and cytosine insertion in the sequences isolated in this study suggests at least 2 strains of CaHV-1 circulating in Brazil (Pará and BTU-1).     

Effects of delmadinone acetate on pituitary-adrenal function, glucose tolerance and growth hormone in male dogs

Objective To characterise the effects of delmadinone acetate on the pituitary-adrenal axis, glucose tolerance and growth hormone concentration in normal male dogs and dogs with benign prostatic hyperplasia.
Design A prospective study involving nine normal male dogs and seven with prostatic hyperplasia.
Procedure Delmadinone acetate was administered to six normal male dogs and seven dogs with benign prostatic hyperplasia at recommended dose rates (1.5 mg/kg subcuta-neously at 0, 1 and 4 weeks). Three normal controls received saline at the same intervals. Blood concentrations of ACTH, cortisol, glucose, insulin and growth hormone were measured over 50 days. Intravenous glucose tolerance and ACTH response tests were performed before and after treatment in the nine normal animals.
Results A substantial suppression of basal and 2 h post-ACTH plasma cortisol secretion was demonstrated after one dose in all dogs given delmadinone acetate. Individual responses after the second and third administration varied between recovery in adrenal responsiveness to continued suppression. Plasma ACTH concentration was also diminished after one treatment. No effects were evident on glucose tolerance or serum growth hormone concentrations.
Conclusion Delmadinone acetate causes adrenal suppression from inhibition of release of ACTH from the pituitary gland. Treated dogs may be at risk of developing signs of glucocorticoid insufficiency if subjected to stressful events during or after therapy. Neither glucose intolerance nor hyper-somatotropism seems likely in male dogs given delmadinone acetate at the recommended dose rate, but the potential for excessive growth hormone secretion in treated bitches remains undetermined.     

Plasma cortisol responses to three cortico-trophic preparations in normal dogs

Objective To compare cortisol responses to three corticotrophic preparations in normal dogs.
Animals Eight clinically normal dogs (four intact males, four intact females) of medium size.
Procedures Each dog received four treatments on four separate occasions in a duplicated Latin square pattern. Treatments were two adrenocorticotrophin (ACTH) preparations given intramuscularly at 2.2 U/kg, one of the ACTH preparations given intramuscularly at 1 U/kg and a synthetic polypeptide with ACTH-like activity (tetracosactrin, cosyntropin) given intravenously at 5 μg/kg. Plasma samples were taken for cortisol assay before and at 0.5, 1, 2 and 4 h after treatment.
Results Plasma cortisol concentrations were similar with the two ACTH preparations and at both dose rates. Tetracosactrin produced smaller mean peak cortisol concentrations, which tended to occur earlier than with ACTH, and smaller values for the area under the curve of plasma cortisol concentration from zero time to 4 h.
Conclusion The findings suggest that canine adrenal function can be tested adequately by giving ACTH intramuscularly at 1 U/kg and measuring plasma cortisol in samples taken at 0 and 2 h, or by giving tetracosactrin intravenously at 5 μg/kg and determining cortisol concentration at 0 and 1 h.