Effect of surgical removal of endometrial cups on concentrations of chorionic gonadotrophin and subsequent fertility in the mare.

Seven pregnant mares underwent general anaesthesia, laparotomy, hysterotomy and removal of a 50-day conceptus. Eversion of the uterine horn through the hysterotomy site allowed direct visualisation and electrosurgical removal of endometrial cup tissue from 5 randomly selected mares (Nos 1-5), while cup tissue in 2 mares (Nos 6 and 7) was left intact. Two pregnant mares served as unoperated controls (Nos 8 and 9). Efforts to re-establish pregnancy were initiated 20 days after surgery. Serum samples collected before surgery and during the post-operative period were analysed for concentration of horse chorionic gonadotrophin (CG) by radioimmunoassay. Mean (+/- sd) weight and area of removed tissue was 9.91 +/- 4.6 g and 22.4 +/- 5.9 cm2, respectively. Concentrations of CG ranging from 3440 to 21,220 ng/ml were highest at the time of cup removal (50 days) and declined thereafter. Peak concentrations of CG at the time of surgery were not linearly correlated (r = -0.59) with mass of excised cup tissue. Individual CG half-life values for Mares 1-5 ranged from 5.4 to 8.8 days (mean 7.1 +/- 1.2 days). Peak CG concentrations occurred 68 days after conception with a rate of disappearance (half-time) of 13.4 +/- 0.4 days in Mares 6 and 7 and at 74 and 78 days after conception with a half-time of 14.0 +/- 5.7 days in Mares 8 and 9. Mares 1-5 exhibited behavioural oestrus and ovulation 30-44 days after surgery. Pregnancy occurred in 3 mares within 41 days after surgery and was associated with concentrations of CG below 200 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

The correlation between serum selenium and blood selenium in cattle.

The selenium (Se) concentration of paired blood and serum samples from cattle was determined by 2 methods: 1) atomic absorption spectroscopy using hydride generation (HG-AAS), and 2) inductively coupled argon plasma emission spectroscopy using hydride generation (ICP). Samples from 327 cattle were analyzed by HG-AAS, and samples from 344 cattle were analyzed by ICP. The data were examined by linear regression analysis, and the technique of inverse prediction was utilized to determine prediction intervals for estimating blood Se concentration from known serum Se concentration. The correlation coefficients, by simple linear regression of serum Se on blood Se, were 0.79 (r2 = 0.62) and 0.88 (r2 = 0.77) for the HG-AAS data and the ICP data, respectively. For the HG-AAS data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. For the ICP data, the inverse prediction formula for estimating blood Se when serum Se is known, at the 95% prediction interval, was [formula; see text]. The prediction intervals were quite wide, and the accuracy of estimating blood Se from a known serum Se was not useful for diagnostic purposes. The use of serum Se concentration to assess nutritional status of cattle with respect to Se does not appear to be appropriate.

Pathology of Campylobacter jejuni abortion in sheep.

Campylobacter jejuni was inoculated intravenously into pregnant ewes on gestation days 114 and 123 to reproduce ovine abortion. All ewes aborted 7-12 days post-inoculation. High numbers of C. jejuni were isolated from ewe tissues (caruncle, bile, cecal feces), fetal tissues, and placenta. C. jejuni colonies were identified in caruncles and placenta by light microscopy and immunoperoxidase techniques. Histologically, inoculated ewes had a severe purulent endometritis with vasculitis. Placentas from inoculated ewes and field cases showed necrosis and purulent inflammation; however, placentas from inoculated ewes had large numbers of bacterial colonies compared to few bacteria found in field cases. Histologically, only one fetus from the inoculated ewes showed lesions (purulent bronchopneumonia), whereas all fetuses from field cases had a distinct bronchopneumonia, and one fetus showed multifocal hepatic necrosis. These results suggest that C. jejuni (serotypes Penner 1 and Lior 2) is an important abortifacient organism for sheep.

Cytoplasmic estrogen receptors in bovine uterus and uterine tube (oviduct).

The effects of progesterone (P) or estradiol benzoate (EB) on unfilled uterine and uterine tubal (oviductal) cytoplasmic estrogen receptors (ER) were studied in nulliparous heifers. Progesterone (4.4 mg/kg of body weight) in oil EB (350 micrograms) in oil, or oil vehicle only (C) were injected IM 24 hours after the end of estrus. The heifers were euthanatized 36 hours later. There was a difference (P less than 0.005) in the concentration of ER among treatment groups, but no difference (P greater than 0.05) between the ER concentrations in the uterus and uterine tube within each treatment group. The affinity constant (KA) of the uterine tubal ER was similar among the treatment groups (P greater than 0.15), and there was no difference (P greater than 0.05) in the KA between the uterus and uterine tubal ER within the P and C treatment groups. The KA of the uterine ER of the EB-treated heifers was greater (P less than 0.001) than that in either P- or C-treated heifers.

Oviduct (uterine tube) transport of ova in the cow.

Normal oviduct (uterine tube) transport of ova was studied in 12 nulliparous heifers oophorosalpingohysterectomized at various times (range, 26 to 85.25 hours) after the end of estrus. The mean oviduct length +/- SEM was 19.7 cm +/- 0.38. The means of left and right oviduct length were not different (P greater than 0.10). The ampulla and isthmus of the oviduct could be indentified grossly by a definite reduction in lumen size and represented 0.66 and 0.34 of the total oviduct length, respectively. The oviduct ipsilateral to ovulation was divided into eight equal segments. Each segment and the uterine horn were flushed with saline solution. An ovum or zygote was recovered from the oviduct of nine heifers. A zygote was surgically recovered from the uterus of one heifer at 76.75 hours after the end of estrus. An ovum or zygote was not recovered from two of the heifers. A significant linear relationship (P less than 0.01) existed between the estimated time after ovulation and the distance the ovum or zygote had traveled. Therefore, the ovum or zygote in these heifers was transported through the oviduct at a constant rate.

Effects of progesterone or estradiol on uterine tubal transport of ova in the cow.

An experiment was designed to determine the effect of progesterone (P) or estradiol benzoate (EB) on uterine tubal transport of ova in the cow. Intramuscular injections of P, EB, or corn oil (C) were administered to heifers 24 hours after the end of estrus. The heifers were euthanatized 60 hours after the end of estrus and the location of the ovum or zygote was determined. Venous serum levels of progesterone and estradiol-17beta were measured by radioimmunoassay. The mean uterine tube (UT) length was 23.9 cm. An ovum or zygote was recovered from 11 of 14 heifers. Serum levels of progesterone and estradiol-17beta were above normal bovine levels following the P and EB treatments, respectively. The mean UT ovum transport rates were 0.42, 0.21 and 0.23 cm/hour in the P, EB and C treatment groups, respectively. The UT ovum transport rate was increased (P<0.05) by the P treatment and EB treatment had no effect (P > 0.05) when compared with the C treatment.