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1.
Parturition and retention of fetal membranes were induced with PGF2 alpha in 3 primiparous dairy cows. Starting on day 12 post partum (PP) the cows were treated with 500 micrograms i.m. of ACTH-analogue (tetracosactid) every 6 h for 6 times. Changes in plasma concentrations of cortisol, progesterone and 15-ketodihydro-PGF2 alpha were evaluated immediately after treatment. The effects on the resumption of ovarian activity were evaluated by clinical and ultrasound examinations and by progesterone and 15-ketodihydro-PGF2 alpha analyses for 56 days after parturition. Treatment was able to induce a statistically significant (p < 0.01) similar increase in cortisol and progesterone after both the 1st and the 6th injections, in all cows. No changes in 15-ketodihydro-PGF2 alpha concentrations were seen after any of the injections of ACTH-analogue. The first corpus luteum (CL) was seen on day 18 PP (cow A), and 28 (cow B) and in both cases it was followed by a normal ovarian cyclicity. No CL was observed during the whole period of study in cow C. Progesterone profiles confirmed these clinical and ultrasonographic findings. The steroid output, especially progesterone, induced by the ACTH-analogue might be a stimulus for the onset of ovarian cyclicity, since 2 of the 3 animals ovulated earlier than expected. These findings point to the fact that interference with the stress system might have a positive effect on ovarian cyclicity. The different pattern of response does however demand further studies.  相似文献   
2.
The present study investigated the changes of serum progesterone (P4) and its faecal metabolites in pregnant and non-pregnant cows (Expt 1) and the feasibilty of using faecal P4 metabolites for early screening of open cows post-insemination (Expt 2). In Expt 1, seven crossbred Holstein-Friesian (HF) cows were studied. Serum and faecal samples were collected once daily from the day of artificial insemination (AI) until 25 days after AI. In Expt 2, 27 crossbred HF inseminated cows were employed. Serum and faecal samples were obtained on the day of AI (day 0) and on days 19-22 post-insemination. Enzyme immunoassay measurements of serum P4 and faecal P4 metabolites were established. The low detection limit of the assay was 0.01 ng/ml and the amount of P4, resulting in a 50% reduction in the initial binding value, was 1.07 ng/ml. The intra- and inter-assay coefficients of variation were <8% and <14%, respectively. A positive correlation between the levels of serum P4 and faecal P4 metabolites was found in every single cow (r = 0.73-0.88, p < 0.001) and pooled data (r = 0.78, p < 0.001). The estimated value of faecal P4 metabolites at 100 ng/g of faeces was equal to the serum P4 levels of 1 ng/ml. The accuracies of pregnancy and non-pregnancy diagnosis based on the analyses of faecal P4 metabolites between day 0 and days 19-22 post-insemination, were 67% and 100%, respectively. In conclusion, the measurement of faecal P4 metabolites can be a potentially alternative method for early screening of open cows post-insemination with the same accuracy and precision, as measured by serum P4 assay.  相似文献   
3.
This study was aimed to investigate the effects of rumen‐protected γ‐aminobutyric acid (RP‐GABA) on apparent nutrient digestibility, growth performance and health status in heat stressed beef cattle. Fifty Jinjiang Yellow cattle were randomly assigned to 5 treatments (10 animals/treatment). Treatments 1 to 5 were basal diets affixed with 0 (control), 8, 16, 24 and 32 mg of RP‐GABA/kg of body weight (BW) respectively. The trial lasted 45 days. Apparent digestibility of crude protein (CP), crude fiber (CF) and calcium (Ca) quadratically increased with increasing RP‐GABA (< .01), while apparent digestibility of phosphorus (P) tended to quadratically increase (= .09). Dietary supplementation with increasing RP‐GABA linearly increased DM digestibility and average daily gain (ADG) (< .01), whereas the feed to gain (F:G) ratio linearly decreased with increasing RP‐GABA (< .01). The average daily feed intake (ADFI) value tended to linearly increase with RP‐GABA supplementation (= .08). Total protein (TP), blood urea nitrogen (BUN) and malondialdehyde (MDA) levels quadratically decreased (< .01) with increasing RP‐GABA, however albumin (ALB), glucose (GLU), superoxide dismutase (SOD), triiodothyronine (T3) and thyroxine (T4) levels quadratically increased (≤ .01). In conclusion, the present results indicated that dietary supplementation with RP‐GABA led to improved nutrient digestibility, growth performance and antioxidant status in heat stressed beef cattle.  相似文献   
4.
The aim of the present study was to determine the effect of heat stress on postpartum (PP) luteal activity and subsequent reproductive performance in lactating cows. Thirty Holstein–Friesian (HF, ≥75%) cows (hot season, n = 15 and cool season, n = 15) were studied over 60 days after calving. The changes of temperature‐humidity index (THI) were monitored within both seasons. Body condition scores (BCS), uterine involution and the ovarian structures were recorded. Plasma samples were obtained three times a week for the analysis of progesterone (P4) and prostaglandin F metabolite (PG metabolite). Subsequent reproductive performance of the cows, calved within the same period was also evaluated. The means of THI for hot and cool seasons varied between 84–87 and 78–83 respectively. A drop of the mean BCS was recorded at 5 weeks PP in the cows during hot season (p < 0.01), however a delay of uterine involution during early PP period in hot season was not clearly seen. The cows with normal PP ovarian cyclicity during hot and cool seasons were 4/15 (26.7%) and 9/15 (60.0%) respectively. A higher percentage of abnormal luteal activity was found in the cows during hot season (p = 0.07) and delayed luteal cyclicity/anovulation was the most pronounced atypical P4 profile. The levels of PG metabolite were not different between groups and the relationship between the levels of PG metabolite and the time of uterine involution was not evident (p > 0.05). The heat detection rates and the pregnancy rates were higher in the cows during cool season (p < 0.05). Additionally, the higher first AI conception rates during cool season were recorded (p = 0.06). In conclusion, heat stress conditions had negative effects on BCS and altered a normal process of ovarian resumption PP, consequently resulted in lower reproductive performance in a tropical dairy herd.  相似文献   
5.
During late bovine pregnancy, several hormones are involved to maintain and develop a successful result with a live calf. These hormones are e.g., progesterone, high levels during the whole pregnancy period, originating from the corpus luteum, maternal adrenals and placenta. Oestrone sulphate, oestrone in its conjugated form, shows elevated levels from about mid-pregnancy until the third stage of parturition (expelling of the fetal membranes). For the onset of normal parturition and the parturition process as such, a change from progesterone to oestrone synthesis is crucial. The increasing levels of oestrone are time-related to an increased synthesis of prostaglandin F(2alpha) (reflected as elevated levels of 15-ketodihydro-PGF(2alpha)) causing prepartal luteolysis and several hormones are then involved in the labour process such as prostaglandin F(2alpha), cortisol and oxytocin. Cortisol might also be an indicator of stressful events for the dam. Levels of pregnancy associated glycoproteins (PAGs), originating from the trophoblastic binucleate cells, are increasing during the last 10 days prior to parturition. All the mentioned hormones have certain functions during pregnancy, more or less understood. However, could deviations from the expected profiles during late bovine pregnancy indicate impaired fetal well-being or be of importance for reproductive performance during the postpartum period? Abortions, stillbirths or dystocia are situations where endocrine profiles might predict the status of the calf. There are two possible approaches to study the endocrine changes in late pregnancy-to follow spontaneous cases of normal or impaired pregnancies or to experimentally disturb the gestation or induce parturition. We have in one study followed pregnant animals to depict reproductive disturbances, both animals with expected normal parturitions and animals where the sire of the calf has given rise to a high incidence of stillborn calves. The number of stillborn calves or dystocia has been small and so far it has not been possible to obtain a clear picture of the usefulness of endocrine parameters to follow fetal well being, but some of the hormonal parameters show a deviating profile. In a small group of animals with induced parturition (PGF(2alpha)), two out of three had parturition problems and one of these animals had a stillborn calf. All three animals had retained fetal membranes. It was possible to demonstrate a deviating endocrine profile in the cow having the stillborn calf in the sense of higher levels of progesterone, cortisol and 15-ketodihydro-PGF(2alpha) at the time of parturition. In both animals with dystocia the levels of oestrone sulphate after parturition were more sustained. Increasing and high levels of PAGs were only demonstrated in the animal with a normal parturition. These studies are ongoing, aiming at finding changes in endocrine profiles related to impaired pregnancies.  相似文献   
6.
The Cow in Endocrine Focus Before and After Calving   总被引:2,自引:0,他引:2  
During the period 1 month before and 1 month after parturition in the cow, several events take place. The dam has to be prepared for the impending parturition and the uterus and ovaries must return to a certain stage to be prepared for a new pregnancy. Most of these processes are due to or reflected in endocrine changes. A special interest is of course the status of the foetus --"foetal well being". The processes could either be considered as normal in a clinical perspective or as impaired (dystocia, small calves, stillbirth, retained foetal membranes, etc.). The main question for this presentation is if normal and impaired performance could be mirrored in endocrine parameters. Many studies have been performed to follow endocrine changes during the periparturient period in the cow. The following parameters have been shown to be the most important and seem to be the most suitable for an endocrine supervision: Endocrine parameter: progesterone; parameter of: corpus luteum, maternal adrenals, placenta. Endocrine parameter: prostaglandin (PG) metabolite; parameter of: placenta, uterus, inflammation. Endocrine parameter: cortisol; parameter of: regulator of prostaglandin synthesis, stress. Endocrine parameter: free oestrogens; parameter of: placenta, ovaries. Endocrine parameter: oestrone sulphate; parameter of: placenta, calf weight. Endocrine parameter: pregnancy-associated glycoproteins (PAG); parameter of: placenta.  相似文献   
7.
The aims of the current study were to illustrate figures for the characteristics of oestrous cycles especially on follicular dynamics, corpus luteum and changes in progesterone and prostaglandin F2alpha, in the Holstein cross-bred dairy heifers. Twenty six healthy and sexual-mature virgin heifers were monitored for signs of oestrus. Their ovaries were sonically examined and the numbers and the sizes of the follicles as well as of the corpus luteum were documented. In our study, no difference in ratio of the 2-wave and 3-wave patterned cycle was evident. Seasons' change did not affect on characteristics oestrous cycles as well as on dynamics of follicles and corpus luteum. The heifers showed high variation in manifesting oestrus especially on a number of hours. The ‘bodily’ oestrous signs lasted longer than did ‘behavioural’ signs and connection of lowering of the back to standing oestrus was established. Certain diversities comparing to of existed dairy breeds were drawn for follicular dynamics, corpus luteum and its progesterone: 1) the 1st an-ovulatory dominant follicles showed higher growth rate and earlier exceeded dominant diameter; 2) the follicle tended to quicker ovulate but with a smaller diameter at ovulation; 3) the corpus luteum exhibited 4−16.5 mm in diameter of central cavity. Connecting to the levels of progesterone, 4) the corpus luteum turned into active, as well as mid-luteal, period quite late, and 5) the duration of the active period of the corpus luteum was shorter, but 6) at the end of the cycle –around the day of oestrus, progesterone remained certain low but significant levels. In conclusion, the Holstein cross-bred dairy heifers in our study faced a problem of delayed post-ovulatory progesterone rise of which underlying causes are needed to be further scrutinised either at endocrine or at cell levels.  相似文献   
8.
During 3 consecutive calving seasons, calving performance, placental characteristics and endocrine profiles of total 98 pregnancies of late pregnant Swedish Red and White (SRB) and Swedish Holstein (SLB) dairy heifers and cows, were investigated. Ninety-four singleton pregnancies and 4 sets of twins were recorded. In animals with singleton pregnancy, 8 stillbirths, 7 weak calves, 3 premature parturitions and 1 abortion were registered. In the SLB heifers, 19% of stillbirth (5/26) were observed, while 5% (2/42) were noted for the SRB heifers. One stillborn calf derived from the SRB cows and none was found from the SLB cows. In the heifers and cows delivering a normal living calf with unassisted parturition, the placentome thickness monitored by ultrasonography was constant towards the end of pregnancy. The numbers of foetal cotyledons varied individually between animals but in total, fewer cotyledons were found in the foetal membranes of the SRB animals than in the SLB animals (69 +/- 19) vs. (88 +/- 29) (p < 0.05). No morphological and numerical differences of the placentome thickness in animals delivering a stillborn or weak calf, compared to animals delivering a normal living calf, could be observed. In animals with unassisted parturition and without birth complications, the levels of progesterone (P4), PGF2alpha metabolite (PG-metabolite), cortisol, oestrone sulphate (E1SO4) and pregnancy associated glycoproteins (PAGs) were not different by breeds and parities. In animals carrying stillbirth, higher levels of E1SO4 were found in 3 SRB animals and 1 SLB heifer, whereas lower levels of E1SO4 were recorded in 3 SLB heifers during the last week of pregnancy, compared to the profiles found in animals with unassisted parturition. Additionally, the levels of PAGs remained low and constant in 1 SRB cow (delivering a stillborn calf), 1 SRB heifer (giving birth prematurely), 4 animals (carrying twins) and 1 aborting SRB cow. Our results show a very high rate of stillbirth in especially SLB heifers and deviating profiles of E1SO4 and PAGs in animals with impaired parturition were recorded.  相似文献   
9.
Parturition was induced in 12 dairy heifers with prostaglandin (PG) F2 alpha about 2 weeks before the expected time of calving. Eight animals gave birth after two injections (group 1), three animals needed more than two injections (group 2) and one animal (cow no. 740) required one injection. All animals in groups 1 and 2 had retained foetal membranes and the time needed to induce parturition was 59 +/- 7 and 149 +/- 10 h, respectively. As cow no. 740 did not have retained foetal membranes and calved 24 h after one PGF2 alpha injection, it was excluded from the results. Udder distension and relaxation of the pelvic ligaments could predict the calving to within 12 h. Furthermore, the pre-calving drop of body temperature could predict the time of parturition to within 16 h. The total white blood cells and polymorphonuclear cells were at their highest values on the day preceding parturition whereas mononuclear cells had a tendency to increase 3 days after calving. Increased levels of haemoglobin were found at the time of parturition, whereas, plasma-calcium levels significantly decreased after parturition (P < 0.001). Progesterone levels markedly decreased after the first PGF2 alpha injection and reached 2 nmol/l at the time of parturition. Plasma levels of oestradiol-17 beta reached the peak at the time of parturition, whereas, the highest levels of the PGF2 alpha metabolite and cortisol were recorded 16 h after calving.  相似文献   
10.
The high incidence of stillbirth in Swedish Holstein heifers has increased continuously during the last 15 years to an average of 11% today. The pathological reasons behind the increased incidence of stillbirth are unknown. The present experiment was undertaken to investigate possible causes of stillbirth and to study possible physiological markers for predicting stillbirth. Twenty Swedish Holstein dairy heifers sired by bulls with breeding values for a high risk of stillbirth (n = 12) (experimental group) and a low risk of stillbirth (n = 8) (control group, group B) were selected based on information in the Swedish AI-data base. The experimental group consisted of 2 subgroups of heifers (groups A1 and A2) inseminated with 2 different bulls with 3.5% and 9% higher stillbirth rates than the average, and the control group consisted of heifers pregnant with 5 different bulls with 0%-6% lower stillbirth rates than the average. The bull used for group A1 had also calving difficulties due to large calves as compared to the bull in group A2 showing no calving difficulties. The heifers were supervised from 6-7 months of pregnancy up to birth, and the pregnancies and parturitions were compared between groups regarding hormonal levels, haematology, placental characteristics and calf viability. In group A1, 1 stillborn, 1 weak and 4 normal calves were recorded. In group A2, 2 stillborn and 4 normal calves were registered. All animals in the control group gave birth to a normal living calf without any assistance. The weak calf showed deviating profiles of body temperature, saturated oxygen and heart rates, compared with the normal living calves. No differences of the placentome thickness, measured in vivo by ultrasonography were seen between the groups. The number of leukocytes and differential cell counts in groups A1 and A2 followed the profiles found in the control group. In group A1, a slight decrease of oestrone sulphate (E1SO4) levels was found in the animal delivering a stillborn calf from the first 24-h blood sampling at 6 weeks to the second at 3 weeks prior to delivery, while the levels of E1SO4 at both periods in the animal delivering a weak calf followed the profile in animals delivering a normal living calf. During late pregnancy and at the time of parturition, the levels of E1SO4 and PAGs in animals delivering a stillborn or weak calf (from group A1) followed the normal profiles found in animals delivering a normal living calf. In group A2, low levels of E1SO4 and pregnancy associated glycoproteins (PAGs) over 24 h at both 3 and 6 weeks prior to parturition (< 1.5 nmol/L) were recorded in animals delivering a stillborn calf. During late pregnancy and parturition, the levels of E1SO4 and PAGs were slightly lower during 30-50 days prior to delivery and increased with a lower magnitude at the time of parturition. In conclusion, our results indicate that the aetiology behind stillbirth varies depending on the AI-bulls used and is associated with dystocia or low viability of the calves. Deviating profiles of oestrone sulphate (E1SO4) and pregnancy associated glycoproteins (PAGs) in animals delivering a stillborn calf not caused by dystocia were observed, suggesting placental dysfunction as a possible factor. The finding suggests that the analyses of E1SO4 and PAGs could be used for monitoring foetal well-being in animals with a high risk of stillbirth at term.  相似文献   
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