The Role of the Endometrium in Endocrine Regulation of the Animal Oestrous Cycle

A critical analysis of the results of research in the function of the endometrium was carried out and a view point presented. The role of the endometrium in endocrine regulation of the oestrus cycle can be summarized as follows: 1. The transfer of prostaglandin F_2α (PGF_2α) from the uterus to an ovary, which causes luteolysis, occurs mainly via the lymphatic pathways. 2. The system of retrograde transfer of PGs enables PGF_2α and PGE₂ to reach the myometrium and endometrium with arterial blood at high concentration. In the luteal phase, PGF_2α, together with the increasing concentration of progesterone, constricts the arterial vessels of the uterus; in the follicular phase and in early pregnancy, PGE₂ together with oestrogen and embryonic signals, relaxes the arterial vessels. In addition, this system protects the corpus luteum from premature luteolysis during the cycle and luteolysis during early pregnancy. 3. In days 10–12 of the cycle, the blood flow in the uterus decreases by 60–70% in pigs and around 90% in sheep. This causes ischaemia and local hypoxia confirmed by the presence of hypoxia inducible factor and thus remodelling of the endometrium commences. 4. The pulsatile elevations in PGF_2α concentration occurring in the blood flowing out of the uterus during the period of luteolysis and the next few days, do not result from increased PGF_2α synthesis as suggested in numerous studies. They are the effect of excretion of PGF_2α and its metabolites together with lymph and venous blood and tissue fluids in which prostaglandin accumulates.     

Effects of Oxygen Exposure and Gentamicin on Stallion Semen Stored at 5 and 15°C

This study was undertaken to investigate the effects of storage of stallion semen in a defined milk protein extender at 5 and 15°C under either anaerobic or aerobic conditions, with or without addition of the antibiotic gentamicin. Semen samples were collected from eight fertile stallions and stored for 96 h (day 0–4) and assessed daily for motility, velocity and membrane integrity (viability) using a CASA system. Samples for bacteriology assessment were taken on day 2 of storage. No significant (p > 0.05) differences in motility, velocity or viability were observed between treatments on days 0–2. On days 3 and 4, semen stored without gentamicin at 5°C had a significantly (p < 0.05) better semen quality compared with storage at 15°C without gentamicin, irrespective of oxygen exposure. On days 3 and 4, motility and velocity were greater in samples stored at 15°C with gentamicin, compared with the corresponding treatments without antibiotic (p < 0.05). This effect was also evident for viability on day 4. The decline in semen quality observed at 15°C most likely resulted from the effect of bacterial growth. Bacterial growth was the greatest in samples stored at 15°C without gentamicin, under both anaerobic and aerobic conditions (p < 0.05). Bacterial growth was inhibited by adding of gentamicin at 15°C, which accordingly reduced the decline in semen quality. Addition of antibiotic to samples stored at 5°C had no significant effect on any parameter analysed. In conclusion, storage at 15°C can be achieved by using an extender containing the antibiotic gentamicin. Storage at 5°C tended to maintain better semen quality irrespective of oxygen exposure, and did not necessitate an antibiotic treatment.     

Effects of exercise on the morphology of the myenteric neurons of the duodenum of Wistar rats during the ageing process

This study aimed to evaluate the effects of regular physical activity on the morphology of the myenteric plexus of the duodenum in rats during the ageing process. To this end, 45 Wistar rats were divided into three groups: C (sedentary – 6 months old), S (sedentary – 12 months old) and T (trained – 12 months old). The animals of group S were given with a physical activity programme consisting of a 10-min-treadmill workout once a week. The animals of group T were submitted to the physical activity programme five times a week. Their duodenums were collected and submitted to the techniques of nicotinamide adenine dinucleotide (NADH)-diaphorase enzyme histochemistry for whole-mount preparations and transmission electron microscopy. No differences in the constitution of the myenteric plexuses were found when the sedentary and trained groups were compared with the control group. The ultrastructural features were similar for the three groups. However, it was verified that the physical activity of the trained animals resulted in a similar myenteric neuron morphology to that of the adult animals (6 months old), thereby confirming its beneficial effect, as the sedentary animals had larger alterations in the collagen fibrils and the basal membrane that occur through ageing. The quantitative analysis showed that the NADH-diaphorase positive neurons decreased with ageing and increased with physical activity ( P  > 0.05). No significant alteration ( P  > 0.05) in the neuronal profile area of the NADH-diaphorase positive neurons has been observed with ageing.     

Secondary Intracranial Neoplasia in the Dog: 177 Cases (1986–2003)

Background: This study investigates the frequency, location, and clinical findings associated with 177 secondary brain tumors in dogs.
Hypothesis: Secondary intracranial neoplasia is more common than primary intracranial neoplasia in dogs during the time period studied, and hemangiosarcoma (HSA) is the most common secondary intracranial tumor.
Animals: One hundred and seventy-seven client-owned dogs presented to the Matthew J. Ryan Veterinary Hospital between 1986 and 2003.
Methods: Medical records were searched for a diagnosis of intracranial neoplasia in dogs who underwent complete postmortem examination. Of these dogs, those with a diagnosis of primary intracranial neoplasia were excluded.
Results: Of the 177 secondary brain tumors, 51 (29%) were HSAs, 44 (25%) were pituitary tumors, 21 (12%) were lymphosarcomas, and 21 (12%) were metastatic carcinomas. The average age at diagnosis was 9.6 ± 3.0 years. Most tumors were located in the cerebrum, and a mentation change was the most common presenting clinical sign. On postmortem examination, the same tumor that was in the brain was also present in the lung in 84 cases (47%), in the kidney in 62 cases (35%), and in the heart in 55 cases (31%).
Conclusions and Clinical Importance: Secondary intracranial neoplasia in dogs was more common than primary intracranial neoplasia during the time period studied. Many of these dogs had related disease in other body systems that was apparent on diagnostic tests such as thoracic radiography.     

Effects of cereals and/or protein supplement extrusion on diet utilisation and performance of intensively reared cattle

The effect of extruding the cereal and/or the protein supplement of a compound feed on its nutritive value and on the performance of intensively reared male calves was studied. The compound feed was formulated with 0.65 of a cereal blend (60:40 maize:barley), 0.25 of a protein blend (1/3:1/3:1/3 raw soybeans:peas:lupins), and 0.08 of urea to contain 0.17 of crude protein. It was tested without extruding (NE) and with the cereal blend (CE), the protein blend (PE) or both (CPE) extruded. Another non-extruded compound feed with mainly soybean meal as the protein supplement (NE-SBM) also was studied. The five experimental compound feeds together with barley straw were offered ad libitum to 50 male Friesian calves (112 kg initial live weight) for 13 weeks, recording individual feed intake and live weight gain. Crude protein (CP) solubility and in vitro and in situ CP degradation of experimental compounds, and in vitro gas production kinetics, in vivo digestibility and urinary allantoin excretion of diets were determined. Cereal extrusion promoted a greater gas production at all incubation times (p < 0.001), associated to the increase in starch gelatinisation. PE and NE-SBM compounds showed lower in vitro (p < 0.01) and in situ (p < 0.001) CP degradability than the other feeds. Ingredient extrusion did not affect apparent DM, OM and CP digestibilities, but diet CPE showed a lower NDF digestibility (p < 0.05) than the others (0.293 vs. 0.420, 0.387, 0.390 and 0.407 with CPE vs. NE, CE, PE and NE-SBM, respectively). The apparent EE digestibility increased (p = 0.053) with the inclusion of extruded ingredients, (0.799, 0.749 and 0.794 vs. 0.719 and 0.702 with CE, PE and CPE vs. NE and NE-SBM, respectively). Daily allantoin excretion was lower (p < 0.01) in calves receiving the CPE diet than in those receiving the NE, PE and NE-SBM diets. Treatments did not affect the average daily gains (1.61 ± 0.022 kg d^− 1), however calves on the CPE diet showed a lower (p < 0.01) concentrate and total conversion ratios than those fed NE, PE and NE-SBM (2.60 vs. 2.79, 2.85 and 2.98 kg concentrate DM kg^− 1 daily gain and 2.93 vs. 3.09, 3.13 and 3.26 kg total DM kg^− 1 daily gain, respectively). The CE diet resulted in numerically higher (p > 0.05) concentrate and total DM conversion ratios (2.72 and 3.02) than CPE and lower (p < 0.05) than NE-SBM. Improvement in feed conversion ratio after extrusion would be related to a better starch utilisation and not to changes in microbial or dietary protein flow to the duodenum, although a better utilisation of fat energy cannot be disregarded.     

Mermithid nematode infection in a colony of blue-winged grasshoppers (Tropidacris collaris)

A die-off occurred in a captive colony of blue-winged grasshoppers (Tropidacris collaris) at the Toronto Zoo. One fourth of the colony died within a year due to infection with worms initially mistaken for nematomorphs but later identified as nematodes belonging to the Mermithidae, genus Mermis. Mortality persisted and the grasshopper population dwindled over the following years. Mermithid larvae developed in the hemocoel of the insects until they eventually emerged from a hollowed-out exoskeleton. Circumstantial evidence suggests that the parasites were introduced with raspberry browse that was grown on site and contaminated with mermithid eggs.     

Differential response of cull cow muscles to the hypertrophic actions of ractopamine-hydrogen chloride

Ractopamine-HCl (RAC) is a beta-adrenergic agonist with variable effects on cattle performance and carcass variables. Cull cows fed RAC (200 mg . head(-1) . d(-1)) demonstrate an increased size of type I and II muscle fibers that does not translate into a larger ribeye area. The objective of this study was to examine the dose-dependent effects of RAC on cull cow muscle morphometrics. Eighty-eight cull beef cows representing 2 breed types (n = 44 each) were fed 0, 100, 200, and 300 mg . head(-1) . d(-1) of RAC for the last 28 d of a 54-d feeding period. On d 54, cows were slaughtered, and samples of the LM and semimembranosus muscle (SM) from 16 randomly selected carcasses (n = 4 per treatment) were taken for measurement of beta (2)-adrenergic receptors and type I, IIA, and IIX myosin heavy chain (MyHC) gene expression. Twenty-four hours postmortem, LM, SM, infraspinatus (INF), and vastus lateralis samples from 40 randomly selected carcasses (n = 10 per treatment) were obtained and frozen for immunohistochemical analysis. Muscle fiber cross-sectional area and diameter, MyHC isoform expression, and fiber-associated nuclei numbers were measured. Ractopamine dosage exhibited differential effects on muscle morphometrics and MyHC gene expression. Muscle fiber cross-sectional area and diameter were increased (P < 0.05) by RAC in INF type I and IIA fibers and SM type IIA fibers. Ractopamine increased (P < 0.05) MyHC type IIX mRNA and tended to increase (P < 0.10) beta(2)-adrenergic receptors in the SM; a change in mRNA abundance was not detected for either gene in the LM. Treatment with RAC decreased (P < 0.05) fiber-associated nuclei numbers in the INF, vastus lateralis, and LM but did not affect (P > 0.05) MyHC or beta-adrenergic receptor expression. These results indicate that cull cow feeding programs may consider supplementing RAC as a means of adding value to cuts within the chuck, such as the INF.     

Acute lead intoxication in a pregnant mare

Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain 2614 ppm Pb. Lead concentrations in the brain, liver, stomach and kidney were 29, 4, 6 and 2 ppm wet weight, respectively.