Uterine activity in cows during the oestrous cycle, after ovariectomy and following exogenous oestradiol and progesterone.
ABSTRACT Uterine activity was monitored in three, 2-year-old nulliparous Ayrshire heifers using intrauterine balloon-tipped catheters and pressure transducers during the oestrous cycle, after ovariectomy and following the intravenous infusion of progesterone and oestradiol-17 beta. During the oestrous cycle uterine activity, as measured by the frequency and amplitude of contractions, was greatest around oestrus and declined during the luteal phase of the cycle; there was a close correlation with peripheral progesterone concentrations. In two animals after bilateral ovariectomy spontaneous uterine activity persisted, whilst in the third animal the uterus was quiescent. In the first two heifers intravenous progesterone infusions reduced the spontaneous uterine activity, eventually completely abolishing it. There was evidence of a dose response effect at the two infusion rates. Oestradiol benzoate infusions initially inhibited spontaneous uterine activity before stimulating contractions with some evidence of a dose relationship. As demonstrated in normal cyclical and steroid-infused animals, uterine activity appears to be under the influence of both hormones although the influence of progesterone is greater.
- SourceAvailable from: Zerai Woldehiwet[Show abstract] [Hide abstract]
ABSTRACT: Endometritis in breeding cattle occurs during the postpartum period, and is associated primarily with contamination of the reproductive tract involving Arcanobacter pyogenes (formerly Actinomyces pyogenes) together with Gram-negative anaerobes. Polymorphonuclear inflammatory cells (PMNs) contribute partly to the defense mechanisms against micro-organisms contaminating the vagina and uterine lumen, whose phagocytic activity depends on bacterial opsonisation by humoral antibodies; significant numbers of lymphocytes are also present. Whilst leukocyte numbers in the uterine lumen are relatively high during metoestrus and dioestrus compared to other phases of the oestrous cycle, their functional activity is unaffected. Humoral antibody concentrations in the reproductive tract are stimulated following exposure to local antigen, and the response is site dependent; of the several different classes of immunoglobulins, IgG predominates in the uterus and IgA the vagina. Only a portion of the total IgG1 found on the uterine lumen is synthesised locally in the endometrium, the remainder and all of the IgG2 is derived from the local uterine blood supply. Generally, concentrations of immunosuppressant proteins present in the uterine lumen increase under progesterone dominance, and these inhibit lymphocyte proliferation, making the uterus more susceptible to infection. The relationship between uterine susceptibility to micro-organism contamination and the luteal phase of the oestrous cycle is still unclear. Intrauterine infusion of immunomodulators such as E. coli lipopolysaccharides (LPS) or oyster glycogen, in healthy cows and those with endometritis, stimulates leukocytes to migrate into the uterine lumen. At a dosage rate of 100 microg, lipopolysaccharides are not absorbed by the healthy endometrium and do not alter the oestrous cycle length. It is unknown, whether a similar dose can be absorbed through an inflamed endometrium in naturally occurring cases of endometritis to cause systemic illness. Currently, prostaglandin F2alpha is recommended for treating endometritis in both cycling and non-cycling cows, but its mode of action in non-cycling cows is not fully understood. The efficacy of endometritis treatment using an intrauterine infusion of an immunomodulator in cases occurring naturally has not been determined on a large scale.Animal Reproduction Science 10/2001; 67(3-4):135-52. · 1.90 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Prostaglandins are widely used in herd management due to their luteolytic properties. They have also a direct effect on the myometrium. We hypothesized, that dissimilar prostaglandin preparations would differ as to their contractile effect. Intrauterine pressure was recorded during the diestrus of lactating dairy cows using a transcervically placed intraluminal pressure microtransducer. After recording physiologic uterine motility for 30 min, prostaglandins (dinoprost, DL-cloprostenol, D-cloprostenol) or a placebo was administered intramuscularly, followed by a 2-h recording period. Significant differences were found for the area under the curve (P < or = 0.05) and mean amplitude (P < or = 0.05), whereas the number of spikes per 15 min and the baseline pressure during the last 3 min of every recording period did not differ significantly among treatments. Peak values for area under the curve and mean amplitude were found between 15 and 30 min after administration of DL-cloprostenol, while dinoprost yielded the steadiest plateau from this period until the end of the recording session. These results contrast with those of earlier studies comparing prostaglandins after intravenous administration.Theriogenology 08/1998; 50(3):445-55. · 2.08 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: To determine the effects of estradiol cypionate (ECP) on measures of reproductive efficiency in postparturient dairy cows. Randomized clinical trial. 273 cows in a single herd in California. Twenty-four hours after parturition, 122 cows were treated with ECP (4 mg, IM); the remaining 151 cows were untreated controls. Percentages of cattle with abnormal findings during uterine palpation 27 to 40 days after parturition were compared between groups, along with days to first artificial insemination (AI), percentages of cows that were not pregnant after the first AI, and days to pregnancy. Treatment with ECP did not have a significant effect on whether results of uterine palpation 27 to 40 days after parturition were abnormal, days to first AI, or odds that a cow would be pregnant after the first AI. Treatment with ECP appeared to have a negative effect on days to pregnancy (hazard ratio, 0.72) Results suggest that prophylactic administration of ECP during the early postparturient period in dairy cows did not have measurable beneficial effects on reproductive efficiency.Journal of the American Veterinary Medical Association 08/2001; 219(2):220-3. · 1.72 Impact Factor