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.     

Populations of Salmonella typhimurium in internal organs of experimentally infected carrier swine.

Experiments were conducted to determine comparative populations of Salmonella typhimurium in the most commonly infected body organs of long-term carrier swine. Naturally farrowed Salmonella-free pigs (n = 58) were orally exposed to S typhimurium when they were 47 days old. Necropsy of 3 to 5 randomly selected pigs was conducted at 3, 7, 10, 14, and 17 days and at 3, 4, 5, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. Mean populations (log10/g) of S typhimurium in palatine tonsils, ileum, cecum (wall and contents), ascending colon (wall and contents), and mandibular and ileocolic lymph nodes were estimated at each necropsy, using a most-probable-number method of bacteriologic examination. Populations of organisms in cecum and colon were similar to each other throughout the duration of the study. Mean populations (log10/g) associated with cecal and colonic walls decreased from 6.1 and 6.6, respectively, during the first postexposure (PE) week to less than or equal to 1.67 from PE weeks 4 to 28. Populations (log10/g) associated with cecal and colonic contents decreased from 5.6 and 5.5, respectively, at PE day 3 to 2.5 and 2.7, respectively, at PE week 4, and remained less than or equal to 2.8 until week 28. Populations (log10/g) associated with intestinal walls and contents were closely correlated during the study. Population (log10/g) in the ileum was greater than or equal to 5.3 from PE days 3 to 17, then varied between 5.4 and -0.4 up to PE week 28.(ABSTRACT TRUNCATED AT 250 WORDS)     

Survey of internal parasites in Western Australian pig herds. 1. Prevalence

Between September 1982 and March 1984, 101 Western Australian piggeries with 15 or more sows were surveyed to determine the prevalence of internal parasites and examine the relationship between parasitism and management practices. Faecal samples were collected from 20 pigs in 4 age groups in randomly selected piggeries, and examined for the presence of eggs of helminth parasites and protozoan cysts. Evidence of nematode parasites was found in 79% of piggeries. Sows were more commonly affected than other classes of pigs with worm eggs being found in 68% of herds. Oesophagostomum spp was the most prevalent worm species, being found in pigs from 65% of piggeries and in sows in 60% of herds. Ascaris suum was the most common species of worm found in growing pigs. There was no evidence of infection with either Metastrongylus spp or Strongyloides spp in any of the herds sampled. Oocysts of coccidia were found in pigs from 56% of piggeries and Balantidium coli cysts were detected in pigs from 42% of piggeries sampled.     

Efficacy of nemadectin, a new broad-spectrum endectocide, against natural infections of canine gastrointestinal helminths

Nemadectin, a new broad-spectrum endectocide, was highly efficacious against natural infections of all the major canine gastrointestinal helminths. At single oral dosages of 0.2-0.4 mg kg-1 body weight (BW), a liquid formulation administered in gelatin capsules was 100% effective in eliminating natural infections of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Uncinaria stenocephala. Tablets (267 mg) containing 4.6% nemadectin given at a rate of 1/3 tablet per 20 kg BW (0.2 mg nemadectin kg-1) were 100% active against T. canis, A. caninum and U. stenocephala. With both formulations, an increase in the dose rate to 0.6-0.8 mg kg-1 BW resulted in 99-100% elimination of Trichuris vulpis infections. No adverse reactions were observed in any of the treated dogs.     

An evaluation of an oral formulation of moxidectin against selected anthelmintic-resistant and -susceptible strains of nematodes in lambs

The efficacy of an oral formulation of the newly developed parasiticide, moxidectin, was tested against benzimidazole-resistant Haemonchus contortus, Trichostrongylus colubriformis, and Nematodirus spathiger, levamisole-resistant Ostertagia circumcincta, and susceptible Cooperia curticei infections in weaned lambs. Thirty-two lambs were experimentally infected with mixed doses of the above strains of nematodes. They were allocated into four treatment groups by stratified randomisation using liveweights and faecal egg counts 28 days later. One group received moxidectin at 0.2 mg/kg liveweight, one group oxfendazole at 4.5 mg/kg liveweight, one group levamisole at 7.5 mg/kg liveweight and the last group remained untreated as the control. Worm burdens in the lambs at slaughter 10 days after oral treatment confirmed the resistance status of the nematode strains used, and showed that moxidectin had a greater than 99.9% efficacy (p<0.01) against all of them. No adverse effects due to treatment with moxidectin were observed in any of the animals.     

Interactions between different media and follicle‐stimulating hormone supplementation on in vitro culture of preantral follicles enclosed in ovarian tissue derived from collared peccaries (Pecari tajacu Linneaus, 1758)

The aim was to verify the effect of follicle‐stimulating hormone (FSH) supplementation to α‐MEM+ or TCM199+ media on the in vitro development of ovarian preantral follicles (PFs) derived from collared peccaries. Ovaries (n = 5 pairs) were collected and divided into fragments destined to control group (non‐cultured) or treatments that were cultured for 7 days. The PFs morphology, growth and activation were evaluated by classical histology. The immunohistochemistry markers Ag‐NOR and PCNA were used for nuclear proliferation analysis, and the picrosirius red labelling was used for ovarian extracellular matrix (ECM) evaluation. After 7‐day culture, only the TCM199+ treatment maintained the proportion of intact PFs similar to day 1 (63.2%), but no differences were found among treatments (p > .05). In addition, a significant increase in the growing follicles proportion was verified for all the treatments, indicating follicular activation (p > .05). By the Ag‐NOR analysis, only the TCM199+/FSH maintained the nuclear proliferation similar to the first day (p > .05). The picrosirius red staining revealed that the ECM remained intact in all the treatments (p > .05). We suggest the use of TCM199+ medium supplemented of FSH for the in vitro development of peccaries PFs under 7‐day culturing conditions.     

An entropy approach to spatial disaggregation of agricultural production

While agricultural production statistics are reported on a geopolitical – often national – basis we often need to know the status of production or productivity within specific sub-regions, watersheds, or agroecological zones. Such re-aggregations are typically made using expert judgments or simple area-weighting rules. We describe a new, entropy-based approach to making spatially disaggregated assessments of the distribution of crop production. Using this approach, tabular crop production statistics are blended judiciously with an array of other secondary data to assess the production of specific crops within individual ‘pixels’ – typically 25–100 square kilometers in size. The information utilized includes crop production statistics, farming system characteristics, satellite-derived land cover data, biophysical crop suitability assessments, and population density. An application is presented in which Brazilian state level production statistics are used to generate pixel level crop production data for eight crops. To validate the spatial allocation we aggregated the pixel estimates to obtain synthetic estimates of municipality level production in Brazil, and compared those estimates with actual municipality statistics. The approach produced extremely promising results. We then examined the robustness of these results compared to short-cut approaches to allocating crop production statistics and showed that, while computationally intensive, the cross-entropy method does provide more reliable estimates of crop production patterns.