G. C. van der Weyden

Fertility, production and culling following cesarean section in dairy cattle

A population-based historical cohort study design was used to investigate the effects of a cesarean section on calf mortality, fertility, milk production and culling on 35 Dutch dairy farms. The data were collected during a routine herd health and production control program. Cows undergoing a cesarean section had a higher calf mortality rate, a longer interval from first service to conception and a smaller risk for retained placenta than control cows, those with spontaneous deliveries and those with dystocias. Cumulative milk production at 100 days was lower and the risk of being culled was higher for cows with cesarean sections than for the control cows.

Cervical ripening and parturition in cows are driven by a cascade of pro-inflammatory cytokines.

The final stages of cervical ripening and parturition resemble an inflammatory process. Although the role of cytokines in both spontaneous and experimentally induced parturitions has been described in several small laboratory animals and humans, the involvement of pro-inflammatory and regulatory cytokines in physiologic parturition in cows has not been determined. In this study, the cytokine expression profiles were assessed in bovine cervical tissue at several stages of pregnancy and at parturition. Serial biopsy samples of the cervix were obtained from 10 cows on day 185 and day 275 of pregnancy (which was on average 5.4 days before parturition) and at parturition. Messenger RNA expression levels of interleukin (IL)-1beta, IL-6, IL-8, IL-10 and tumour necrosis factor (TNF)alpha were determined using real-time polymerase chain reaction and the number of neutrophils and eosinophils was estimated by Luna and Sirius Red staining. At parturition, IL-8 expression had increased 430-fold (p < 0.001) when compared with that of the day 185 of pregnancy, large numbers of neutrophils had invaded the cervix while eosinophils remained scarce, IL-1beta had increased eightfold (p < 0.05) and IL-6 had not changed significantly. Additionally, IL-10 was increased by 10-fold (p < 0.001) and TNFalpha decreased by 57% (p < 0.05) when compared with that of the day 185 of pregnancy. The large increase in expression of IL-8, enabling the influx of neutrophils, is indicative of its important role in the final stage of cervical ripening and at parturition. As previous studies have shown that neutrophils excrete matrix metalloproteinases (MMP), this might contribute to softening of the cervix. In contrast, the only slightly increased levels of IL-1, steady concentrations of IL-6 and decreased TNFalpha, the potential consequences of increased IL-10 expression, indicate that final cervical of cows in ripening at term parturition is an inflammatory process influenced by regulatory cytokines.

Concentration of growth hormone, prolactin and cortisol in fetal and maternal blood and amniotic fluid during late pregnancy and parturition in cows with cannulated fetuses

Growth hormone, prolactin and cortisol concentrations were measured by radioimmunoassay in samples of fetal and maternal plasma and amniotic fluid from 15 days before until 24 hours after spontaneous parturition in cows. Average gestation length in ten cows with chronically catheterized fetuses was 267 ± 2.7 days (SEM). Mean fetal plasma GH concentrations decreased gradually during the last 15 days before birth (r = 0.925, P < 0.01) and were 4–6 times higher than mean concentrations in maternal plasma. The latter did not change during the period under observation. GH and PRL concentrations in amniotic fluid were low during late gestation and showed no changes around parturition. Prolactin concentrations changed only in maternal plasma and reached peak values just before birth of the calf. The fetal cortisol concentration was significantly (P < 0.05) elevated at Days −9 to −7 compared with that in samples taken before Day −9. A further increase occurred during the last week before birth. It is concluded that prepartum changes in the concentrations of GH, PRL and cortisol in fetal and maternal plasma and amniotic fluid are not synchronous but take place according to a pattern which is rather specific for each hormone in each of the compartments.

Myometrial electrical activity throughout the entire course of pregnancy in the ewe

Bipolar electrodes were implanted into the myometrium of three cycling ewes. Natural mating took place 35, 47 and 91 days after surgery, and all three animals became pregnant. Two of them were slaughtered 18 and 40 days after mating, the third delivered twin lambs 144 days after mating. The uterine electrical activity was recorded during pregnancy and parturition. From the 3rd until the 27th day after mating the uterus appeared to be quiescent. From the 5th wk of pregnancy until induction of parturition on day 141, electrical activity was observed to occur in episodes of 5--10 min, with a frequency of 1--3 per 2 h. The episodes are separated by periods of inactivity. The amplitudes of the electrical discharges increased gradually during pregnancy, although the plasma progesterone levels increased also. It is concluded that (1) the implanted electrodes did not interfere with normal reproductive processes such as conception, maternal recognition of pregnancy, implantation and fetal development: (2) a distinct pattern of electrical activity can be detected as early as the 5th wk of pregnancy.

Cesarean section in dairy cattle: A study of risk factors

Abstract Cesarean sections were studied on 35 Dutch dairy farms using data collected through a routine herd health and production control program. Over a period of 8 years and 9 months there were 198 cesarean sections out of a total of 15,051 calvings. The 198 cesarean sections were compared with a referent group of 841 calvings that was randomly selected from the original 15,051 calvings. A population-based, case-referent study design was used to investigate risk factors for cesarean section. Risk factors for cesarean section consisted of first parity, single male calf, long gestation period, long interval between first service and conception, long dry period, sired by a bull of double-muscled structure or Piedmont bull, under 730 days of age at first calving, and having a previous cesarean section. A short dry period and a short gestation were protective factors.

Ultrasonic cervimetry to study the dilatation of the caudal cervix of the cow at parturition.

The objective of this study was to investigate the temporal changes in dilatation of the caudal cervix during induced calvings (n = 5). We used ultrasound cervimetry, allowing the continuous recording of the distance between a transmitting and receiving ultrasound crystal, which were implanted opposite to each other on the caudal rim of the cervix. We started recording between 19 and 21 h after injecting a prostaglandin analogue (PG) on day 272 of gestation. A fluid-filled catheter had been introduced transcervically between the fetal membranes and the uterine wall for measurements of intra-uterine pressure (IUP). While the characteristics of calving varied widely between the five animals, it appeared possible to divide the process of dilatation into four phases. During the latent phase, which lasted until 25-43 h after PG, no net gain in dilatation occurred. We found an acceleration phase (4.3-6.8 h), in which the dilatation rate speeds up (0.49-0.84 cm/h) in three of the cows. During the phase of maximum slope (lasting 0.5-4.8 h), we measured an even higher rate (1.47-8.48 cm/h), decreasing again during the deceleration phase (rate 0.24-2.28 cm/h) in four cows. The quality of the IUP measurements precluded us from continuously investigating the relationship between cervical dilatation and uterine contractions. However, short term simultaneous recordings revealed that the cervical opening changed momentarily in the absence of IUP during the latent phase, while during the phase of maximum slope, temporary changes of dilatation coincided with uterine contractions. We concluded that the method of ultrasound cervimetry used in this study provides a valuable way to study the process of cervical dilatation in parturient cows in vivo.

Follicular dynamics and oestrous detection in Thai postpartum swamp buffaloes (Bubalus bubalis).

This study characterized follicular activity and oestrous behaviour from 5 to 9 days post-calving up to the 4th ovulation postpartum (pp) in 16 multiparous (range 2-7 parities) Thai swamp buffalo cows (Bubalus bubalis), aged 4-12 years and weighing from 432 to 676 kg. Ovarian follicular activity was examined by transrectal ultrasonography (TUS) every morning. Oestrous detection was performed twice daily by direct personal observation of behaviour and for presence of clear cervical mucus discharge and indirectly by video camera recording during 21 h/day. A follicular wave-like pattern was present before the 1st ovulation leading to short oestrous cycles. Growth rates and maximum diameters of the ovulatory follicles did not differ between the 1st and 4th ovulations. However, growth rate for non-ovulatory dominant follicles (DF) before the 1st ovulation was lower than for the ovulatory follicle (p<0.05). In addition, the diameter of all ovulatory follicles (14.3 ± 0.46 mm, n=39) was significantly larger (p < 0.01) than those of the preceding last but one non-ovulatory DF (10.8 ± 0.20 mm, n = 5), but similar to the last preceding non-ovulatory DF diameter (12.92 ± 0.96 mm, n = 14). Short oestrous cycles were most common between the 1st and 2nd ovulations (93.75%, 15/16 cows, 10.2 ± 0.38 days) decreasing in prevalence thereafter (50%, 3/6 buffaloes, 12.0 ± 1.53 days). Oestrous signs were relatively vague around the 1st ovulation pp to become more easily detectable thereafter. This study suggests that properly fed swamp buffaloes could be mated successfully within 2 months pp, at their 2nd spontaneous ovulation, provided oestrous detection is at least performed daily at 06:00-08:00 hour.

Preliminary Observations on Myometrial Electrical Activity before, During and after Parturition in the Cow

In eight cows bipolar silver electrodes were implanted on the outside of the uterine wall at different locations, 9 – 30 days before calculated term. In addition, open-end catheters were placed between the uterine wall and the foetal membranes in seven of these animals in order to measure pressure fluctuations. In two cows parturition occurred within 4 days after the operation. In five cows parturition started around calculated term while in one cow parturition was induced with flumethason 30 days after operation. In three of the eight animals an uterine torsion had to be connected during the early state of parturition. During the last week of pregnancy, periods (6 – 30 minutes) of distinct electrical activity (groups of trains) occurred at irregular intervals (15 – 120 minutes) in the distended parts of the pregnant horn. The first sign of impending parturition was the increase in the duration of the individual trains between 24 and 12 hours before birth. Around the same time electrical activity became evident in the undistended parts of the uterus. Regular uterine contractions (tubo-cervical as well as cervico-tubal) occurred only after the expulsive stage had started. During the first hours postpartum the majority of the contractions progressed in a tubo-cervical direction.

Cardiotocography in cows: A method for monitoring calves during delivery.

Fetal ECG-electrodes and an intrauterine catheter were inserted into 15 Holstein-Friesian cows during their first stage of labor to make a cardiotocogram. Simultaneously, fetal heart rate and intrauterine pressure were recorded until completion of fetal expulsion. Immediatly post partum the viability of the calf was assessed by clinical evaluation and measurements of blood pH, base excess (BE) and pCO(2). Fetal heart rate patterns and their changes were evaluated according to standards used in human medicine. Basal fetal heart rate (90 to 120) in 10 calves gradually increased towards the end of parturition, with a marked loss of variability. Decelerations, coinciding with periods of increased intrauterine pressure, occurred in all cows. When decelerations occurred beyond the end of a contraction the calf was born in a poor condition. Accelerations were only recorded in two cows. Many of the fetal heart rate changes observed were similar to those which in human cardiotocography are considered to be signs of fetal distress. Further investigation is needed to establish the predictive value of fetal heart rate patterns in cows, which would be a welcome addition to improved fetal diagnostics during parturition.

Smooth Muscle Cells of the Bovine Cervical Stroma may have a Secretory, rather than a Contractile Function during Parturition

The bovine cervix contains a large amount of smooth muscle cells distributed over an outer muscular layer and within a stromal layer. The stromal layer exhibits no electromyographic (EMG) activity at parturition. This leads to the question whether the stromal smooth muscle cells of the bovine cervix are prepared to contract with parturition, or whether they have another function. To this end, cervical biopsies were repeatedly taken from 10 pregnant cows at day-185 and -275 of gestation, at spontaneous, uncomplicated calving and at 30 days after calving. The smooth muscle bundles of the stroma were immunohistochemically analysed (n = 5) with regard to their integrity and cellular density, and the degree of staining for connexin-43, smooth muscle actin alpha (SMA), desmin and vimentin. Additionally, the mRNA expression for connexin-43, SMA, desmin and vimentin was determined with RT-PCR (n = 5). The smooth muscle tissue was arranged in bundles, also at parturition. However, the cellular density of these bundles and the SMA mRNA expression were decreased at parturition. Additionally, the SMA staining and connexin-43 expression and staining remained constant during pregnancy and at parturition. This might indicate that stromal smooth muscle cells are not prepared to contract with parturition, in contrast to the myometrial smooth muscle cells. The smooth muscle cells, stained for SMA, also expressed vimentin, and the proportion of co-expression was increased at day-275 of pregnancy. This suggests that the stromal smooth muscle cells predominantly have a secretory function in cows.