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.     

Forms of employment and species caseload of veterinary practitioners in New Zealand

A survey by means of a postal questionnaire was undertaken to investigate the patterns of work and the need for information of veterinary practitioners in New Zealand. Of the 670 eligible veterinarians, 399 practitioners (60 per cent) participated in the survey. Of these, 38 per cent were in large animal practice (less than 20 per cent of work devoted to cats and dogs) and 31 per cent were in small animal practice (more than 80 per cent of work with cats and dogs). The remaining 31 per cent were in mixed practice, with a workload intermediate between the other two groups. Across the entire sample of practitioners, cats and dogs took up the largest number of veterinary hours per person (1092 hours per year). Dairy cattle were second (438 hours), and horses third (302 hours). Deer and goats ranked next, and each used more veterinary hours per person than did either sheep or beef cattle. Other species comprised very minor parts of the overall workload. Women spent a much higher proportion of their working hours with small animals and a much lower proportion with horses than did men. For other species workload patterns were similar between men and women. In relation to employment of the practitioner group, women were under represented, compared with men, among those with responsibilities for the management of practices, even when account was taken of the fact that the women in the sample were younger. Fewer than one per cent of men in the sample were not employed full-time, whereas 15 per cent of the women were in part-time employment. The survey indicates that there has been a substantial change in the demographic structure of the veterinary profession and the forms of veterinary work carried out. It also shows that the differences in work and career patterns between men and women need more intensive study to improve the accuracy of predictions of future requirements for veterinary manpower.     

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.     

Manipulating Chlorine Atom Bonding on the Si(100)-(2 x 1) Surface with the STM

Chlorine atoms strongly chemisorbed at dangling bond sites on the Si(100)-(2 x 1) surface are observed by scanning tunneling microscopy (STM) to hop between adjacent sites. The origin of this behavior is suggested to be an interaction between the field of the probe tip and the dipole moment of the silicon-chlorine bond. Chlorine atom migration is shown to be facilitated by the presence of a metastable chlorine bridge-bonded minimum. The STM probe was used to excite single chlorine atoms into this bridging configuration, resulting in a local population inversion. Selective application of voltage pulses between the probe tip and the surface rearranged the local bonding and induced transformations between different types of chlorine sites. In this manner, adsorbed species can be dissected and their composition and structure directly probed.     

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.     

POSSIBLE PATHWAYS OF CONTAMINATION OF MEAT AND BONE MEAL WITH SALMONELLA

Samples taken at various points along the processing line in 2 rendering plants showed that post-processing contamination occurs almost immediately after termination of the heat process in the percolator and surge bin. Further contamination occurs at each processing stage. In plant A 12.5% of the samples collected from material leaving the surge bin, 36% of the samples of product after it has passed the milling stage and 61% of samples collected from the stored product were found to be contaminated with salmonellas. In plant B the results were 15%, 40% and 69% respectively. Heavy contamination of product left overnight in percolators and surge bins, which are not cleaned routinely, was considered an important source of early post-processing contamination. The ecology was found to be similar at both plants despite the fact that in one plant the uncooked and cooked areas were separated completely, whilst this was not the case in the other plant. None of the air samples collected yielded salmonellas, while nearly all the insect samples collected in the rendering plants yielded salmonellas.