Relationships between antral follicle count, blood serum concentration of anti-Müllerian hormone and fertility in mares.

INTRODUCTION: The anti-Müllerian hormone (AMH) plays an inhibitory role during folliculogenesis by regulating the number of follicles entering the growing pool. Antral follicle counts (AFC) are highly correlated with serum AMH concentrations and both appear to be related to the ovarian reserve in several species. Few data on AMH and AFC in mares exist, especially with regard to fertility. Therefore, the objective of the current study was to investigate the interrelationship between antral follicle count, serum AMH concentrations and fertility outcome in mares. One hundred and twenty-seven mares were enrolled in the study and grouped according to their reproductive status. Around time of estrus, serum AMH concentrations and AFC before and after ovulation were determined. Mares were artificially inseminated and pregnancy diagnosis was performed 14 to 18 days later. A high inter-individual variability in AFC and AMH concentration and a positive relationship between AMH and AFC for follicles ≤ 30 mm in diameter were observed, with a stronger correlation in mares older than 18 years. A high correlation between AFC measurements before and after ovulation was identified. The AFC after ovulation was higher than AFC before ovulation. AMH concentrations were neither related to the mares' reproductive status nor to age, number of cycles needed for pregnancy and pregnancy outcome. Excepted for a higher AFC in the middle-aged mares (9-18 years) compared to the younger mares (< 9 years), no associations between AFC and age, reproductive status as well as fertility of mares were found. This study confirms the relationship between AFC and AMH and a high degree of reproducibility of AFC measurements. However, based on our findings, neither AFC nor AMH are useful predictors of fertility in mares.

INTRODUCTION: Il existe peu de données sur l'AMH et l'AFC chez les juments, particulièrement en rapport avec la fertilité. L'objectif de cette étude était donc d'examiner la relation entre le compte de follicules antraux, le taux sérique d'AMH et la fécondité chez les juments. Cent vingt-sept juments ont été inclues dans l'étude et groupées selon leur état reproducteur. Les taux sériques d'AMH et l'AFC ont été déterminés pendant l'oestrus avant et après l'ovulation. Les juments ont été inséminées artificiellement et le diagnostic de gestation réalisé 14 à 18 jours plus tard. Une grande variabilité interindividuelle de l'AFC et l'AMH et une corrélation positive entre l'AMH et l'AFC pour les follicules de diamètre ≤ 30 mm ont été observées, cette dernière étant plus forte chez les juments âgées de plus de 18 ans. L'AFC après ovulation était supérieur à l'AFC avant ovulation, et une forte corrélation entre les deux mesures a été constatée. Aucun lien entre les taux sériques d'AMH, l'état reproducteur, l'âge, le nombre de cycles œstraux par gestation et le taux de gestation n'a été observé. Hormis un AFC supérieur chez les juments d'âge moyen (9-18 ans) comparé aux juments plus jeunes (.

Effect of prostaglandin E2, DL-cloprostenol, and prostaglandin E2 in combination with D-cloprostenol on uterine motility during diestrus in experimental cows.

Prostaglandin F(2alpha) is used in dairy herd management because of its luteolytic properties and for its direct effect on the myometrium in cows diagnosed with endometritis. Prostaglandin E(2) has a contractile effect on the bovine uterus. In human medicine, prostaglandin E(2) is routinely used to maintain labor and to ripen the cervix. We hypothesized, that a combination of prostaglandin F(2alpha) and prostaglandin E(2) would provoke a long-lasting increase in intrauterine pressure (IUP) and uterine motility as compared to either prostaglandin group. Intrauterine pressure was recorded during the diestrus of eight lactating dairy cows using a transcervically placed intraluminal pressure microtransducer. After recording of physiologic uterine motility for 30min, prostaglandins (DL-cloprostenol, PGE(2), PGE(2) in combination with D-cloprostenol) or placebo were administered, followed by a 2h recording period. Significant differences were found for the area under the curve, the mean amplitude and the intrauterine pressure, whereas the number of pressure waves did not differ significantly among treatments. Peak values for area under the curve and mean amplitude were found during the first 15min for the combination of PGE(2) and D-cloprostenol. During the last 15min of the recording session, area under the curve and mean amplitude were increased only for the combination of PGE(2) and D-cloprostenol as compared to placebo. Although PGF(2alpha) and PGE(2) provoke an increase in intrauterine pressure, only their combination guarantees a significant effect over a 2h recording period.

An in vitro study on spontaneous myometrial contractility in the cow during estrus and diestrus.

Myometrial smooth muscle strips were collected from slaughtered cows in estrus and diestrus. Longitudinal and circular smooth muscle strips were mounted in organ baths and after equilibration time and 2g preload, their physiologic contractility was recorded for 3h. Area under the curve (AUC), mean amplitude (MA) and frequency of contractions (F) were studied. Differences between cycle phases, between muscle layers and over the recorded time period were statistically evaluated. In the cow, physiologic contractility patterns (measured as AUC and MA) of circular versus longitudinal myometrial strips are always different during the 3h recording. Significant differences between estrus versus diestrus are only found for circular layers, but not for longitudinal layers. Significant differences over time are only found for longitudinal layers.

The effect of infection with bovine viral diarrhea virus on the fertility of Swiss dairy cattle.

Bovine viral diarrhea virus is a major cattle pathogen with a worldwide distribution. Animals may be infected with BVD virus transiently or persistently. Transient infection leads to protective immunity. Persistent infection is unique because it is associated with an immunotolerance that is specific to the infecting strain of BVD virus. Persistent infection results from viral invasion of fetuses between the second and fourth month of development. Such animals are of prime importance in the epidemiology of BVD because they shed large amounts of virus, and thus serve as a constant source of infection for non-immune animals. Infection of pregnant animals during the first two months of gestation may result in an increased rate of return to estrus. Animals infected in the period of five months to birth may abort or give birth to calves with malformations. The effects of BVD virus on fertility and gestation are well documented from experimental infection. However, much less is known of the extent of losses under field conditions. The main reason for this may be the multitude of other causes of increased return rates and gestation failures. In addition, the incidence of infection with BVD virus may vary over time and depends on management practices. In this study, we investigated the impact of BVD virus on gestation failures under field conditions in a large cattle-breeding area of Switzerland, where no specific measures to control BVD are in effect. Our approach consisted of relating seroconversions to BVD virus with the rate of return to estrus, abortion, and birth of calves with apparent malformations. These parameters of fertility were compared to those of animals immune to BVDV infection due to previous exposure to the virus and animals without seroconversion. Our data show that infection with BVD virus during the first 45 days of gestation did not influence the rate of return to estrus. By contrast, we observed a statistically significant increase in the abortion rate in mid-term gestation (Days 46 to 210) while no such effect was observed in the later stages of gestation. No clinically manifest malformations were observed in the offspring of animals that had seroconverted to BVD virus. In our study population the prevalence of BVDV antibody positive cattle varied only slightly between 78% and 80% over the period of observation. Our data showed that 7% (CI: 2.4-14%) of fetal deaths may be attributable to infection with BVD virus.

Abortion rate during the second half of gestation of cows undergoing surgery in lateral recumbency as compared with cows of a control population.

In a retrospective study, we compared the abortion rates of 59 cows in the second half of gestation, admitted to the Clinic for Food Animals and Horses (1993-1996) with a strictly focal problem (head region, udder and teats, locomotor system) requiring surgery in lateral recumbency, to the abortion rate of a control cow population. Before surgery, a uterus relaxant was given in 42 cases, and 17 cows were untreated as to pregnancy. Cows included in the reproduction health program of the Department of Fertility and Reproduction were used as a control population. Data of 1,736 cows pregnant in the second half of gestation per year were available for the same time period (1993-1996). Abortion rate was 5.08% for the cows undergoing surgery in lateral recumbency as compared with 5.18% for the cows of the control population. There was no significant difference between the two populations (P > 0.05). Thus, the risk for abortion in the cows in question is not elevated as compared with the control population.

[Surgical and conservative methods for removing mummified fetuses in cattle]. / Chirurgische und konservative Methode zur Entfernung von abgestorbenen Feten beim Rind.

The purpose of this study was to describe the findings and therapy in 4 cows and 1 heifer with mummified fetus. All animals were admitted at the clinic after several unsuccessful therapies with prostaglandin F2alpha and local uterine infusions. All animals were in good condition. In case 1, diagnosis of mummified fetus could not be confirmed after manual rectal palpation and ultrasonography whereas cases 2, 4, 5 all had mummified fetus. In case 3, the fetus was in maceration. Initial therapy consisted of administration of prostaglandin F2alpha and prostaglandin E2 followed by repeated administration of prostaglandin E2. Mummies (length from apex to rump 13-32 cm) could be taken out within 3 to 6 days per vias naturales in cases 2, 4, 5 and in case 3, bones (maximal length 4 cm) could be unhinged. The structure in the uterus of case 1 could not be mobilised and was consequently removed under sight control using colpotomy followed by hysterotomy. Animals 2, 3, 4 and 5 were pregnant on the occasion of telephone inquiry. On the basis of our results, we recommend the conservative medical therapy with PGE2 for cases of mummified fetus. Colpotomy and hysterotomy are reserved as therapy feasible if the use of prostaglandin E2 is not successful.

Reproductive efficiency of cows with endometritis after treatment with intrauterine infusions or prostaglandin injections, or no treatment.

Data from 3276 cows with 6598 lactations in 85 herds participating in a herd health monitoring programme were selected for an observational study. Cases of endometritis were diagnosed based on a clinical examination after 21 days postpartum. The cases were grouped by the severity of endometritis (mild, severe) and by the treatment performed (intrauterine infusion, prostaglandin injection, no treatment). The conception rates and the calving-to-conception intervals of these groups were compared statistically. Conception rate was lower in cows with severe endometritis compared to cows with mild endometritis while it did not differ between treatment groups. In cows with mild endometritis a significantly longer calving-to-conception interval was observed if intrauterine infusions were performed compared to the other two treatment options. The occurrence of other fertility problems during the same service period had a significant effect on conception rate and calving-to-conception intervals. In cows with severe endometritis intrauterine or prostaglandin treatments appeared to be beneficial, whereas intrauterine infusions in cows with slight endometritis had a negative effect on reproductive efficiency.

Effect of two dosages of d-cloprostenol on intrauterine pressure and uterine motility during dioestrus in experimental cows.

Prostaglandins are commonly used in herd management for their luteolytic properties; however, prostaglandins also have a direct contractile effect on the myometrium. We hypothesized that different dosages (0.15 and 0.3 mg) of d-cloprostenol, a synthetical prostaglandin F2 alpha preparation, would differ as to their contractile effects on the uterus. Intrauterine pressure was recorded during dioestrus of lactating dairy cows, using a transcervically placed intraluminal pressure microtransducer. After recording of physiological uterine motility for 30 min, a placebo or d-cloprostenol at one of the two different dosages 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 15-min 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 the lower dosage of d-cloprostenol, and between 75 and 90 min after administration of the higher dosage. Using the higher dosage of d-cloprostenol, a steady plateau from 15 to 30 min after administration until the end of the recording session was obtained. Thus, double the luteolytic dose of the d-cloprostenol preparation gives a significantly better reaction in terms of uterine contractility than the single dose.