Suppression of ovarian progesterone production in dairy cows using an implant of GnRH-agonist (deslorelin) for the purpose of evaluating progesterone metabolism

OBJECTIVE: To evaluate the potential of an implant of a GnRH-agonist (deslorelin) to create a progesterone free animal suitable for studying progesterone (P4) metabolism in intact cows by measuring blood P4 and faecal P4 metabolites. METHODS: Experiment 1: Eighteen non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to one of three groups to study plasma P4 concentrations preceding an intravaginal insert. These groups comprised: i) a deslorelin group (GnRH-agonist implanted); ii) a PGF group receiving two injections of prostaglandin (PGF2alpha) 12 days apart; and, iii) an ovariectomised (OVX) group. An intravaginal device (CIDR) was inserted into the vagina of each animal and left in place for 11 days. Plasma P4 concentrations were measured during the study period. Experiment 2: Twelve non-lactating cycling Holstein-Friesian cows, 4 to 7 years old, were allocated to two groups: i) a deslorelin group (GnRH-agonist implanted); and ii) an ovariectomised group. Plasma P4 and faecal P4 metabolites (20-oxo-pregnanes, 20alpha-OH and 20beta-OH) were monitored for a period of 5 weeks. RESULTS: Experiment 1: Average plasma P4 concentration did not differ between the three groups (1.28, 1.43 and 1.55 ng/mL for deslorelin, OVX and PGF cows, respectively, P = 0.8) during the period of supplementation. Experiment 2: There was no difference in plasma P4 (mean plasma P4 < 0.02 ng/mL, P = 0.9) and faecal P4 metabolites between deslorelin and OVX cows 2 weeks after the implantation (P = 0.7). CONCLUSIONS: These data showed that a GnRH-agonist (deslorelin) implant may be used as an alternative to ovariectomy to create a progesterone free animal suitable for studying the metabolism of administered P4.     

The stress response to environmental change in captive cheetahs (Acinonyx jubatus).

The captive North American cheetah (Acinonyx jubatus) population is not self-sustaining because of high prevalences of unusual diseases and poor reproductive success. Cheetahs are commonly moved between zoos for breeding purposes to maintain genetic diversity within the captive population, and movement may exacerbate infertility and disease. Fecal corticoids were analyzed by radioimmunoassay to measure the stress response of cheetahs to movement between facilities. Fecal samples were collected from 15 cheetahs for 14 days before movement and for at least 30 days after movement. For each cheetah, premovement fecal corticoid concentrations were used to determine baseline and then compared with trends in postmovement concentrations. In general, postmovement corticoid concentrations either increased (n = 8), did not change (n = 2), or decreased (n = 5). Although individual animal differences occurred, corticoid concentrations increased for most animals moved on-exhibit and decreased in animals moved off-exhibit. Animals moving on-exhibit had an 18-times greater risk of having corticoids elevated more than two standard deviations above baseline for 30 days after movement compared with animals that moved off-exhibit. In addition, greater day-to-day variation in corticoids occurred in animals moved on-exhibit. In general, animals with initially low baseline corticoid concentrations had a greater postmovement corticoid response than cheetahs with initially high baseline levels. These results indicate that some cheetahs have a prolonged stress response when moved between facilities, and the magnitude and character of this response is influenced by the exhibit environment.     

Validation of the 13C-urea breath test for use in cheetahs (Acinonyx jubatus) with Helicobacter.

Historically, therapeutic monitoring for prescribed eradication treatment of Helicobacter in cheetahs (Acinonyx jubatus) with associated gastritis has been accomplished only through endoscopic biopsies. The 13C-urea breath test (UBT) can offer an alternative to repeated biopsies for therapeutic monitoring. Five male and five female cheetahs and one male Sumatran tiger (Panthera tigris) were studied. All were clinically healthy before and after this investigation. Breath samples of end-tidal expiration were taken before and after administration of a 13C-enriched urea solution through a gastroesophageal tube. Twenty-milliliter breath samples were taken at 10, 20, 30, and 40 min after administration of the urea solution. The results of the breath analysis were compared with the results of rapid urease testing, histopathologic examination, and impression smears of gastric biopsies taken at the time of the breath test. The sensitivity and specificity for the 13C-UBT in this investigation were 100%. and the positive predictive value and negative predictive value were both 100%. Although the 13C-UBT is a good noninvasive diagnostic tool for monitoring the presence of Helicobacter sp. in the gastric mucosa, endoscopy should still be used for initial diagnosis and grading of gastritis and for monitoring the progression of disease in cheetahs. The 13C-UBT is a valuable, simple, accurate, and sensitive tool for monitoring eradication of Helicobacter during therapy for clinical gastritis.     

Detection and genetic diversity of porcine rotavirus A,B and C in eastern Australian piggeries

Rotaviruses (RV) have a high prevalence in piggeries worldwide and are one of the major pathogens causing severe diarrhoea in young pigs. RV species A, B, and C have been linked to piglet diarrhoea in Australian pig herds, but their genetic diversity has not been studied in detail. Based on sequencing of the structural viral protein 7 (VP7) RVA G genotypes G3, G4 and G5, and RVC types G1, G3, G5, and G6 have been identified in Australian piggeries in previous studies. Although occurrence of RVB was reported in Australia in 1988, no further genetic analysis has been conducted. To improve health management decisions in Australian pig herds, more information on RV prevalence and genetic diversity is needed. Here, 243 enteric samples collected from 20 pig farms within Eastern Australia were analysed for the presence of RV in different age groups using a novel PCR-based multiplex assay (Pork MultiPath™ enteric panel). RVA, RVB, and RVC were detected in 10, 14, and 14 farms, respectively. Further sequencing of VP7 in selected RV-positive samples revealed G genotypes G2, G5, G9 (RVA), G6, G8, G14, G16, G20 (RVB), and G1, G3, G5, G6 (RVC) present. RVA was only detected in young (<10 weeks old) pigs whereas RVB and RVC were also detected in older animals (>11 weeks old). Interestingly, RVB and RVC G-type occurrence differed between age groups. In conclusion, this study provides new insights on the prevalence and diversity of different RV species in pig herds of Eastern Australia whilst demonstrating the ability of the Pork MultiPath™ technology to accurately differentiate between these RV species.     

Early harvest and ensilage of forage sorghum infected with ergot (Claviceps africana) reduces the risk of livestock poisoning

Sorghum ergot produces dihydroergosine (DHES) and related alkaloids, which cause hyperthermia in cattle. Proportions of infected panicles (grain heads), leaves and stems were determined in two forage sorghum crops extensively infected 2 to 4 weeks prior to sampling and the panicles were assayed for DHES. Composite samples from each crop, plus a third grain variety crop, were coarsely chopped and half of each sealed in plastic buckets for 6 weeks to simulate ensilation. The worst-infected panicles contained up to 55 mg DHES/kg, but dilution reduced average concentrations of DHES in crops to approximately 1 mg/kg, a relatively safe level for cattle. Ensilation significantly (P = 0.043) reduced mean DHES concentrations from 0.85 to 0.46 mg/kg.     

人员在岗培训在实施兽药GMP现场管理中的作用

论述了对兽药生产企业进行人员在岗培训的必要性,对实施在岗培训的基本程序和应注意的事项进行了总结,旨在为兽药企业进行GMP现场管理提供参考。