W.H. Johnson

The use of real-time ultrasound rectally for early pregnancy diagnosis in sheep.

Three groups of ewes (n=64) were tested for pregnancy using a real-time ultrasound system rectally, beginning at Day 25 after breeding. The ewes were examined while standing, using a 5 mH(3) transducer designed for equine rectal use. Each examination required less than one minute and produced no apparent distress. The results of the test compare favorably with other methods of early pregnancy detection with a predictive value of a positive test of 97%, a predictive value of a negative test of 80% and an accuracy of 91%.

The developmental competence of bovine embryos with reduced cell numbers

Abstract Early cleavage stage bovine embryos can now be readily produced and maintained in vitro ; therefore, their usefulness for producing identical calves and providing biopsies for sexing was investigated and compared with a conventional method of embryo splitting. Up to half the total number of blastomeres can be removed from 2- to 16-cell embryos without adversely affecting their subsequent development into blastocysts. Two- and 4-cell embryos needed to be maintained at 38°C during manipulation because of their sensitivity to cooling. Until the time of hatching, cell numbers in such blastocysts were reduced in proportion to the numbers of cells originally removed. The transfer of two demi-embryos produced from bisected blastocysts resulted in pregnancy rates similar to that obtained with whole embryos and there were no differences between cell numbers in, or survival of, demi-embryos produced in vitro or in vivo . Multiple calves also have been produced from single blastomeres isolated from 4-cell embryos produced in vitro . Seventy three percent of the 4-cell embryos manipulated produced either 3 or 4 blastocysts. Pregnancy rates resulting from transferred pairs of quarter embryos were lower than from demi-embryos, but there are some indications that success rates may be increased if the smaller embryos are co-transferred with fresh trophoblastic vesicles.

The significance to bull fertility of morphologically abnormal sperm.

Bull fertility depends partially on the quality of the spermatozoa (i.e., different spermatozoa defects) produced in the ejaculate, emphasizing the importance of the interpretation of the spermeogram results. This article discusses the production of normal and abnormal spermatozoa and the influence that spermatozoa defects may have on bull fertility.

Progesterone profiles in postpartum Holstein dairy cows as an aid in the study of retained fetal membranes, pyometra and anestrus

This study was carried out to investigate the utility of enzymeimmunoassay (EIA) - derived progesterone profiles in the investigation of postpartum reproductive abnormalities and the effect of their use on reproductive performance in Holstein cows. Whole milk samples, collected twice weekly from parturition until confirmation of pregnancy or removal from the herd, were assayed for progesterone (P4) concentration using a commercially available microtitre plate EIA. The sensitivity, specificity, precision and accuracy were satisfactory to distinguish cyclic changes of P4 reflecting ovarian activity. The P4 profiles indicated that retained fetal membranes and anestrus were associated with increased mean intervals to first ovulation and first estrus (P < 0.05). The first luteal phase of cows with pyometra was prolonged compared with that of normal herdmates (P < 0.05). Anestrus cows had an increased number of ovulations before first service and before pregnancy (3.9 and 5.9) in comparison with normal herdmates (2.1 and 3.5; P < 0.05). Calving to pregnancy interval was increased above normal (74.8) for pyometra (125.0) and anestrus (152.7) (P < 0.05). Pregnancy rate for anestrus cows (82%) was lower than for normal cows (100%) and more anestrous cows were culled (27%) than normal cows (5%) (P < 0.5). The P4 profiles indicated that the major problem in the herd studied, anestrus (32% incidence rate), was most likely due to the failure to observe estrus rather than acyclicity.

The effect of prostaglandin administration to Holstein-Friesian cows at Day 26 postpartum on clinical findings, and histological and bacteriological results of endometrial biopsies at Day 40

Ninety-two cows that calved between April and August 1984 in a commercial dairy herd were studied. The cows were randomly assigned to receive either cloprostenol (500 mug) or saline placebo on Day 26 postpartum. In addition, each cow was examined per rectum, had three endometrial biopsies taken and milk progesterone level determined. Double-blind techniques were used in administering treatments and in assessing response to treatment. The results of histological and bacteriological assessment of endometrial biopsies and clinical findings at Day 40 were compared between the cows that received prostaglandin at Day 26 and those that did not. Each Day 40 variable which was significantly associated with prostaglandin treatment at Day 26 was regressed against the treatment variable and progesterone level at Day 26 as well as a prostaglandin progesterone interaction term. Prostaglandin-treated cows had less vaginal discharge, smaller diameter uterine horns, less inflammation and fibrosis in the endometrium, and were less likely to have Actinomyces pyogenes isolated from a biopsy at Day 40 than untreated cows. These effects were independent of progesterone level at the time of treatment.

Evaluation of the effect of GnRH on follicular ovarian cysts in dairy cows using trans-rectal ultrasonography.

The objectives of this study were to evaluate ovarian changes in cows with follicular ovarian cysts following treatment with either GnRH or saline. The parameters determined were the intervals from treatment to observation of a CL and from treatment to disappearance of the cyst, and the association between serum concentrations of LH, FSH and the LH/FSH ratio, before and after treatment, with the test intervals. Thirty-nine cows were identified as having follicular cysts. The GnRH treatment induced a significant increase in LH and the LH/FSH ratio. The gonadotropin response was not associated with the intervals from treatment to CL detection or to disappearance of the cyst. Survival curves for the intervals from treatment to CL detection and cyst disappearance indicate that treatment with GnRH or saline did not yield significantly different results for either parameter. The results question the efficacy of treating cystic ovarian disease with GnRH.

The determination and correlation of reproductive parameters of performance-tested Hereford and Simmental bulls

Purebred Hereford and Simmental bulls (n = 120), managed similarly to bulls in the Ontario Bull Evaluation Program, were evaluated for reproductive parameters. Four diets, equivalent except for the form of dietary fiber, were fed in a growth performance trial. Diet had no direct effect (P > 0.10) on any of the reproductive variables examined. Of the 117 bulls that had complete breeding soundness evaluations, 75% were classified as satisfactory potential breeders, 24% as questionable potential breeders and 1% as unsatisfactory potential breeders. The 2 breeds were significantly different (P < 0.05) for several end of test parameters. When controlling for age and weight differences, Herefords had a higher backfat thickness, smaller scrotal circumference, lower paired testicular weight and lower epididymal weight. Semen morphology and motility did not differ (P > 0.10) between the breeds. When examining simple correlations, scrotal circumference was highly correlated with paired testicular weight, moderately correlated with epididymal weight, daily sperm production and extragonadal sperm reserves, and negatively correlated with backfat thickness. Scrotal circumference was not related to backfat thickness when controlling for breed effects. The degree of germinal epithelium loss was moderately and negatively correlated with the percentage of spermatozoa with normal morphology and progressive motility, epididymal sperm reserves and epididymal weight, but was not correlated with scrotal circumference.

Amounts of selected coagulation factors in pre- and post-mortem follicular fluid are similar and do not correlate with molecular mass

This study was designed to evaluate the amounts of coagulation factors and to determine whether the protein profile in pre-ovulatory ovarian follicular fluid aspirated from ovaries collected from mares at slaughter are representative of that in follicular fluid collected from live animals. The proteins evaluated included, (i) albumin, ceruloplasmin and fibronectin, (ii) the procoagulant plasma proteins, Factor V (FV), Factor VII (FVII), Factor X (FX) and prothrombin, and (iii) the anticoagulant plasma proteins, antithrombin and alpha2-macroglobulin. The amounts of the individual proteins were similar in both types of follicular fluid. There was no correlation between the activity of FV, FVII, FX or prothrombin in follicular fluid and their molecular size although a correlation was found for the other proteins. These results suggest that the procoagulant proteins in follicular fluid are not likely derived from plasma. The total protein content of follicular fluid samples collected from both sources was similar and the results determined with the Biuret, Lowry and Biorad methods were also not significantly different (P>0.05).

Ultrastructural assessment of a blastocyst recovered from a cow with subclinical purulent endometritis

A blastocyst was recovered from a cow with subclinical purulent endometritis from which Actinomyces pyogenes was isolated. Ultrastructurally the blastocyst appeared viable, although the zona pellucida and pervitelline cell debris were undergoing phagocytosis by neutrophils. An increase in lysosomal activity was observed in the inner cell mass, which may represent sublethal injury due to inflammatory alteration of the uterine milieu. It was concluded that the embryo was resistant to the bystander effect of the suppurative inflammation but that the altered uterine microenvironment may have caused sublethal blastocyst injury.