Effects of the nitrification inhibitor dicyandiamide on soil mineral N, pasture yield, nutrient uptake and pasture quality in a grazed pasture system

Recent lysimeter studies have demonstrated that the nitrification inhibitor, dicyandiamide (DCD), can reduce nitrate (NO) leaching losses from cow urine patches in grazed pasture systems. The objective of this study was to quantify the effects of fine particle suspension (FPS) DCD on soil mineral N components, pasture yield, nutrient uptake and pasture quality under grazed pasture conditions. A field study was conducted on the Lincoln University dairy farm, Canterbury, New Zealand, from 2002 to 2006. FPS DCD was applied to grazed pasture plots at 10 kg ha^?1 in early May in addition to applied cow urine patches at a nitrogen (N) loading rate of 1000 kg N ha^?1, with DCD reapplied in early August. Soil mineral N levels in the urine patches were monitored. Pasture yield, N and cation concentrations and uptake were measured in treatment urine patches and inter‐urine areas of the pasture. Comparisons were made with control plots which did not receive DCD. NO levels under the DCD‐treated urine patches (0–7.5 cm) were in the order of 10 kg N ha^?1 compared with 40–80 kg N ha^?1 under untreated patches, and soil ammonium (NH) levels were consistently higher under the DCD‐treated patches. The DCD significantly and consistently increased pasture yield in both the urine patches, and inter‐urine areas of the pasture in all 4 years of the trial. Mean annual dry matter (DM) yields over 4 years were inter‐urine areas, 10.3; inter‐urine + DCD, 12.4; urine, 12.4 and urine +DCD 16.0 t DM ha^?1, representing an average DM yield increase of 20 and 29% in inter‐urine and urine patch areas, respectively. On a whole paddock basis, the increase in annual DM yield resulting from DCD application was estimated to be 21%. N, calcium (Ca), magnesium (Mg) and potassium (K) concentrations in pasture were unaffected by treatment with DCD; however, total annual uptake of these nutrients by pasture was significantly higher in all years where DCD had been applied. Pasture DM, protein, carbohydrate, metabolizable energy and fibre levels and sward clover content were not affected by treatment with DCD. The results demonstrate the agronomic value of the DCD treatment in addition to the environmental benefits in a grazed pasture system.     

Neurogenesis in a young dog with epileptic seizures

Epileptic seizures can lead to various reactions in the brain, ranging from neuronal necrosis and glial cell activation to focal structural disorganization. Furthermore, increased hippocampal neurogenesis has been documented in rodent models of acute convulsions. This is a report of hippocampal neurogenesis in a dog with spontaneous epileptic seizures. A 16-week-old epileptic German Shepherd Dog had marked neuronal cell proliferation (up to 5 mitotic figures per high-power field and increased immunohistochemical expression of proliferative cell nuclear antigen) in the dentate gyrus accompanied by microglial and astroglial activation. Some granule cells expressed doublecortin, a marker of immature neurons; mitotically active cells expressed neuronal nuclear antigen. No mitotic figures were found in the brain of age-matched control dogs. Whether increased neurogenesis represents a general reaction pattern of young epileptic dogs should be investigated.     

Effects of fermented garlic powder supplementation on growth performance,nutrient digestibility,blood characteristics and meat quality in growing‐finishing pigs

One hundred pigs (BW = 50.7 ± 1.89 kg) were used to investigate the effects of fermented garlic powder (FGP) in growing‐finishing pigs. Pigs were allotted to one of five treatments, included: (i) NC (basal diet); (ii) PC (NC + 44 mg/kg of Tylosin); (iii) FGP1 (NC + 1 g/kg FGP); (iv) FGP2 (NC + 2 g/kg FGP); and (v) FGP4 (NC + 4 g/kg FGP). Supplemental FGP increased average daily gain (ADG) and gain/feed ratio compared with those fed NC diet throughout the experiment (P < 0.05, linearly). Dietary PC treatment increased the ADG and average daily feed intake during the first 6 weeks (P < 0.05). The inclusion of FGP2 and FGP4 treatments had higher apparent total tract digestibility of dry matter and nitrogen (P < 0.05) than those in the NC treatment. Dietary NC treatment exhibited lower (P < 0.05) lymphocyte count (6 and 12 weeks) and immunoglobulin G (12 weeks) than those in the other treatments. Marbling scores were higher (P < 0.05) in FGP treatment groups than the NC treatments. Pigs fed on FGP2 and FGP4 diets evidenced lower 2‐thiobarbituric acid reactive substances value (P < 0.05) than those in the NC and PC treatments. Collectively, our findings demonstrated that the administration of FGP at a level of 2 or 4 g/kg improved growth performance, nutrient digestibility and meat quality in growing‐finishing pigs.     

Treatment of a metallic foreign body in the cranial cervical region of a horse

Ingestion of foreign bodies is uncommon in horses when compared with indiscriminate grazers such as cattle. This case report describes the diagnosis and treatment of a cervical abscess in a Thoroughbred racehorse thought to be associated with ingestion of wire. Radiographic and ultrasonographic examination provided a diagnosis, and conservative treatment of the lesion with antimicrobials initially allowed the lesion to localise closer to the skin for safer surgical exploration. Intra-operative ultrasonographic imaging facilitated surgical access, removal of the foreign body, and drainage. While surgical treatment is usually necessary to resolve an abscess, initially conservative therapy may help to improve the prognosis by simplifying surgical access and reducing the risk of surgical complications.     

Effects of chicken thymic stromal cells on the growth and differentiation of thymocytes in vitro

We examined contact-mediated effects of chicken thymic stromal cells (TSC) on thymocyte differentiation by co-cultivation of these cell populations. The primary cultures of TSC isolated from thymus mainly have consisted of epithelial cells which were polygonal in shape, possessed long processes and expressed MHC class II antigen. When thymocytes were co-cultured with TSC, 60% to 70% of thymocytes attached to TSC and some of them engulfed underneath TSC. These attached thymocytes were CD4-CD8- and CD4+CD8+ subsets and expressed alpha/beta TCRhigh or gamma/delta TCRlow. Some of the thymocytes attaching to TSC showed an increase of intracellular and nuclear density, fragmentation of cytoplasm and nuclei, and DNA fragmentation. And also, thymocytes attaching to TSC contained a higher percentage of cycling (S and G2 + M phase) cells than nonattaching cells. These results indicate that specific subsets in thymocytes selectively bind to TSC and undergo apoptotic death or proliferation because of interaction with TSC. Chicken TSC may play an important role in thymic differentiation by direct contact within the thymus as in mammals.     

Characterization of age- and location-associated variations in the composition of articular cartilage from the equine metacarpophalangeal joint

Objective: To characterize the impact of age, gender, location and individual animal variation on the composition of articular cartilage from the metacarpophalangeal joint of horses. Design: Cartilage specimens were obtained from the metacarpophalangeal joints of 28 male, female and castrated male horses ranging in age from one day to 27 years of age. Cartilage samples from the distal metacarpus, proximal first phalanx and proximal sesamoids were analyzed separately. Chondrocyte number, DNA content, proteoglycan concentration and total collagen content were determined for each animal and joint location. Results: Age and joint location had a significant effect on chondrocyte number and DNA content with higher cell counts and DNA content detected in cartilage from the youngest age groups and in cartilage from the metacarpus and proximal sesamoids. The influence of age on chondrocyte numbers was not significant in horses over two years of age. Both age and joint location also influenced total proteoglycan and collagen content. Lower proteoglycan and collagen concentrations were detected in younger horses, and cartilage from the metacarpus had lower proteoglycan and collagen concentrations than that from other joint locations. Gender did not appear to influence chondrocyte number or matrix content of equine articular cartilage. However, there was significant residual variation in cellularity, proteoglycan levels and collagen content between individual animals that could not be explained by the signalment factors considered in this study. Conclusions: Future studies examining equine articular cartilage should avoid direct morphologic comparisons between animals of different ages, and any comparisons made between individuals should be interpreted cautiously. In addition, in vitro tissue culture models should avoid the use of cartilage pooled from different animals or from different locations within the same joint.     

Pharmacokinetics of oral ivabradine in healthy cats

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) analytical method for the measurement of the novel heart rate-lowering drug ivabradine and its major metabolite, S-18982, was cross-validated in the plasma of eight healthy cats. Plasma concentrations were then determined after single and repeated oral administration of ivabradine. Individual plasma concentrations versus time from each cat were used in compartmental analysis using the commercially available software WinNonlin. Both ivabradine and S-18982 reached their maximum concentrations of 103.33 and 3.86 ng/mL within 1 h. Following repeated administration, areas under the plasma concentration-time curves for ivabradine and S-18982 did not significantly increase. Two-compartmental and one-compartmental models with first-order input and elimination provided the best fit to the data for ivabradine and S-18982, respectively. Both models were combined to produce a single 4-compartment model characterizing ivabradine and S-18982 pharmacokinetics. The results of this study indicate that repeated oral doses of ivabradine produced plasma drug concentrations suitable for 12-h dosing intervals in healthy cats. Furthermore, the analytical assay and combined ivabradine/S-18982 model provide tools for further evaluation of ivabradine pharmacokinetics and pharmacodynamics in future studies in cats.     

Effect of Experimental Hypothyroidism on Glomerular Filtration Rate and Plasma Creatinine Concentration in Dogs

Background: Hypothyroidism affects renal function in a manner opposite the effects of hyperthyroidism.
Objective: To evaluate the effects of experimentally induced hypothyroidism on glomerular filtration rate (GFR) and basal plasma creatinine concentration in dogs.
Animals: Sixteen anestrous, female dogs.
Methods: Hypothyroidism was induced by administration of ¹³¹I in 8 dogs, and 8 healthy euthyroid dogs acted as controls. Exogenous plasma creatinine clearance (an estimate of GFR) was measured in all dogs before (control period) and 43–50 weeks after induction of hypothyroidism (posttreatment period). Other pharmacokinetic parameters of creatinine were also determined.
Results: No significant difference was observed for basal plasma creatinine concentration and creatinine clearance between control and hypothyroid dogs in the control period. In the posttreatment period, mean ± SD creatinine clearance in the hypothyroid group (2.13 ± 0.48 mL/min/kg) was lower ( P < .001) than that of the control group (3.20 ± 0.42 mL/kg/min). Nevertheless, basal plasma creatinine concentrations were not significantly different between the hypothyroid and control groups (0.74 ± 0.18 versus 0.70 ± 0.08 mg/dL, respectively) because endogenous production of creatinine was decreased in hypothyroid dogs (22 ± 3 versus 32 ± 5 mg/kg/d, P =.001).
Conclusion and Clinical Importance: Hypothyroidism causes a substantial decrease in GFR without altering plasma creatinine concentrations, indicating that GFR evaluation is needed to identify renal dysfunction in such patients.     

Optimum contribution selection using traditional best linear unbiased prediction and genomic breeding values in aquaculture breeding schemes

The aim of this study was to compare genetic gain for a traditional aquaculture sib breeding scheme with breeding values based on phenotypic data (TBLUP) with a breeding scheme with genome-wide (GW) breeding values. Both breeding schemes were closed nuclei with discrete generations modeled by stochastic simulation. Optimum contribution selection was applied to restrict pedigree-based inbreeding to either 0.5 or 1% per generation. There were 1,000 selection candidates and a sib test group of either 4,000 or 8,000 fish. The number of selected dams and sires to create full sib families in each generation was determined from the optimum contribution selection method. True breeding values for a trait were simulated by summing the number of each QTL allele and the true effect of each of the 1,000 simulated QTL. Breeding values in TBLUP were predicted from phenotypic and pedigree information, whereas genomic breeding values were computed from genetic markers whose effects were estimated using a genomic BLUP model. In generation 5, genetic gain was 70 and 74% greater for the GW scheme than for the TBLUP scheme for inbreeding rates of 0.5 and 1%. The reduction in genetic variance was, however, greater for the GW scheme than for the TBLUP scheme due to fixation of some QTL. As expected, accuracy of selection increased with increasing heritability (e.g., from 0.77 with a heritability of 0.2 to 0.87 with a heritability of 0.6 for GW, and from 0.53 and 0.58 for TBLUP in generation 5 with sib information only). When the trait was measured on the selection candidate compared with only on sibs and the heritability was 0.4, accuracy increased from 0.55 to 0.69 for TBLUP and from 0.83 to 0.86 for GW. The number of selected sires to get the desired rate of inbreeding was in general less in GW than in TBLUP and was 33 for GW and 83 for TBLUP (rate of inbreeding 1% and heritability 0.4). With truncation selection, genetic gain for the scheme with GW breeding values was nearly twice as large as a scheme with traditional BLUP breeding values. The results indicate that the benefits of applying GW breeding values compared with TBLUP are reduced when contributions are optimized. In conclusion, genetic gain in aquaculture breeding schemes with optimized contributions can increase by as much as 81% by applying genome-wide breeding values compared with traditional BLUP breeding values.