Plasma Cortisol Concentrations after CIDR Insertion in Beef Cows

The objective of this study was to show plasma cortisol concentration after treatment with controlled internal drug release (CIDR) in non‐suckling beef cows. On day 9 after oestrus, two cows were inserted with CIDR into the vagina for 24 h and the other two cows were treated as a control group. Four days later, the two control cows were treated with CIDR and the other two CIDR‐treated cows were used as controls. Cortisol concentrations were determined by ELISA in plasma samples collected before, during and after insertion of CIDR. There was a significant increase in plasma cortisol concentrations (p < 0.01) after insertion of CIDR. Mean (±SEM) plasma cortisol concentrations increased from 1.3 ± 0.4 to a peak of 8.8 ± 1.1 ng/ml at 5 h and then decreased to basal concentrations at 7 h after insertion of the device. In conclusion, the insertion of intra‐vaginal device causes an increase in plasma cortisol concentrations in beef cows, although the pathophysiological significance of the elevation of cortisol is not known.     

Estrone and Progesterone Plasma Levels of Normal Cows and Cows with Parturient Paresis

Blood plasma concentrations of estrone and progesterone, calcium and inorganic phosphorus were measured in 22 cows (Swedish Red and White Breed) from 4 weeks prepartum up to 6 days post partum. Ten cows with parturient paresis had Ca levels below 6 mg/100 ml. Data from plasma analyses in individual cows were grouped in the following periods: 28–22, 21–15, 14–8, 7–6, 5–4, 3, 2, 1 day(s) before parturition and 1, 2, 3–6 days after parturition. Statistical comparisons of the levels of the hormones and the ratio progesterone/estrone did not reveal any significant differences between the paretic and normal cows at any time period. The results do not support the theories that high systemic levels of estrogens or an imbalance between estrogen and progesterone predispose towards parturient paresis.     

Termination of Pregnancy with Cloprostenol and Dexamethasone in Intact or Ovariectomized Cows

Termination of pregnancy in cows was investigated using sham-operated (SH) or ovariectomized (OV) cows treated with either a saline vehicle (V), cloprostenol (PG), dexamethasone (DEX) or dexamethasone and cloprostenol (DEX+PG). Surgery was done at 210 days of pregnancy and treatment was administered 72 hours later.

Days (mean±S.E.) from treatment to termination of pregnancy for the treatment groups were: sham-operated +vehicle (SH+V): 61.5±11.3; ovariectomized+vehicle (OV+V): 53.4±15.7; sham-operated+cloprostenol (SH+PG): 61.8±1.7; ovariectomized+cloprostenol (OV+PG): 54.5±13.1; shamoperated+dexamethasone (SH+DEX): 74.8±4.8; ovariectomized+dexamethasone (OV+DEX): 2.8±0.4; shamoperated+dexamethasone+cloprostenol (SH+DEX+PG) 26.0±23.0; ovariectomized+dexamethasone+cloprostenol (OV+DEX+PG): 7.2±4.9. Pregnancies in the OV+DEX and OV+DEX+PG groups were terminated significantly earlier than in all other groups (P<0.05) except the SH+DEX+PG group. These findings suggest that dexamethasone will terminate pregnancy in cows near seven months of gestation after the ovarian source of progesterone has been removed by either an injection of prostaglandin or by ovariectomy.

     

Milk Progesterone Profile at and after Artificial Insemination in Repeat-Breeding Cows: Effects on Conception Rate and Embryonic Death

The aim of this study was to investigate whether the skim milk progesterone concentrations at artificial insemination (AI) and day of rise of post-ovulatory progesterone concentration thereafter affect the conception and embryonic death rates in repeat-breeding cows. Milk samples were obtained from 96 repeat-breeding cows that failed to conceive to three or more AIs. The samples were taken from the cows at the day of AI and three times/week until day 45 post-AI. Skim milk was obtained after centrifugation and used for progesterone assay. The cows with a progesterone concentration more than 0.5 ng/ml at AI showed a significantly higher incidence of late embryonic death than those having a progesterone concentration<0.5 ng/ml at AI (p<0.01). As the progesterone level at insemination rose, conception rate declined. A negative correlation was shown between conception rate and skim milk progesterone level at AI. Of 56 cows showing a rise of progesterone to 1 ng/ml or more within 6 days after AI, 28 cows (50%) conceived. On the contrary, only eight of 39 cows (20.5%) conceived when the progesterone rose up to 1 ng/ml after day 6 post-AI. We concluded that increased progesterone concentration at the time of AI and delayed rise of progesterone post-AI might lead to decrease in fertility in repeat-breeding cows.     

雌二醇和孕酮对卵巢摘除大鼠子宫内肥大细胞数量分布的影响

本研究旨在研究雌激素和孕酮对卵巢摘除大鼠子宫内肥大细胞数量的影响，探讨雌激素和孕酮与子宫内肥大细胞之间的相关关系。35只雌性成年大鼠随机分成7组：假手术组（SHAM）、卵巢摘除组（OVX）、卵巢摘除＋雌二醇E2（OVX＋E 20 μg、OVX＋E 100 μg、OVX＋E 500 μg）、卵巢摘除＋孕酮P4（OVX＋P 2 mg、OVX＋P 10 mg）。动物处理7 d后，应用放射免疫分析法检测各组大鼠血清雌二醇和孕酮的含量，用甲苯胺蓝染色显示大鼠子宫内肥大细胞。结果显示：①OVX组大鼠血清雌二醇浓度最低，雌二醇处理后， OVX＋E 20 μg组雌二醇浓度比OVX组升高97.13%、OVX＋E 100 μg组比OVX组升高204.84%、OVX＋E 500 μg组比OVX组升高936.45%；孕酮处理后，孕酮浓度OVX＋P 2 mg组比OVX组升高77.25%、OVX＋P 10 mg组比OVX组升高235.25%，各组差异均显著（P〈0.05）。②雌二醇处理后大鼠子宫内肥大细胞数量减少, 与OVX组比较，OVX＋E20 μg组减少32.65%、OVX＋E 100 μg组减少64.50%、OVX＋E 500 μg组减少74.49%；孕酮处理后，OVX＋P 2 mg组比OVX组增加66.73%、OVX＋P 10 mg组比OVX组减少70.67%。除OVX＋E 20 μg组外，各组与OVX组比较差异均显著（P〈0.05）。随着血清中雌、孕激素含量的升高，大鼠子宫内肥大细胞的数量呈递减趋势，提示雌激素和孕酮对大鼠子宫内肥大细胞的数量有直接的影响。     

Pregnancy‐Associated Glycoprotein (PAG) Profile of Holstein–Friesian Cows as Compared to Dual‐Purpose and Beef Cows

Pregnancy‐associated glycoproteins (PAGs) are produced by mono‐ and binucleate trophoblast cells in the ruminant placenta. PAG appears in maternal blood and, from approximately 4 weeks after fertilization onward, may serve as a reliable means of diagnosing pregnancy. A range of factors are said to affect plasma PAG concentrations, such as number and sex of foetus, mass of calf and placenta, level of milk production and genetic constitution. In this study, PAG pregnancy profiles of a dual‐purpose (Simmental) and two beef breeds (Uckermark and Aubrac) are compared with the profile of the specialized dairy breed Holstein–Friesian. Holstein–Friesian cows were sampled weekly; the levels of the other breeds were presented at 3‐week intervals. The overall significant breed difference (p = 0.013) was founded on deviations during the initial 3 weeks of pregnancy and from 23 weeks onward. During the period critical for the detection of pregnancy, between four and 22 weeks, agreement between PAG levels of various breeds was close (p > 0.05). No significant effect of body mass of cow or calf (relative to mass of dam) was detected. These findings imply that the PAG pregnancy test may be executed uniformly irrespective of breed or type of cow, affirming the suitability of the test as a valuable asset for the cattle industry.     

Pharmacokinetic Profile of Erythromycin after Intramammary Administration in Lactating Dairy Cows with Specific Mastitis

The pharmacokinetics of erythromycin was studied in five lactating dairy cows following single intramammary infusion of 300 mg erythromycin in each of two quarters per cow with specific mastitis. Levels of erythromycin in plasma and quarter milk samples were measured by agar plate diffusion assay using Micrococcus luteus (ATCC 9341) as the test organism. Erythromycin level in plasma reached a peak concentration value (C _max) of 0.07 ± 0.01 μg/ml at 30 min; thereafter, levels declined gradually to reach 0.05 ± 0.00 μg/ml 12 h post drug administration. The pharmacokinetic profile of the drug revealed mean absorption half life (t _1/2ka) as 0.26 ± 0.05 h. The drug was eliminated slowly with elimination half-life (t _1/2β) of 13.75 ± 0.35 h and elimination rate constant (k _el) of 0.04 ± 0.00 h⁻¹. The volume of distribution based on the zero-time plasma concentration intercept of the least-squares regression line of the elimination phase (V _d(B)) was 0.032 L/kg. The drug crossed to untreated quarters also; mean drug levels of 0.20 ± 0.07, 0.23 ± 0.07, 0.17 ± 0.04, and 0.17 ± 0.04 μg/ml were found at 3, 6, 8 and 12 h, respectively. The mean drug concentration for treated quarters was measured as 22.97 ± 2.31 μg/ml milk at first milking (12 h) following drug infusion. No apparent adverse reaction was seen in cows administered erythromycin. It is concluded that following intramammary infusion erythromycin diffuses readily and extensively in various body fluids and tissues and adequate concentration is maintained in udder tissues for at least 12 h post intramammary administration. Thus, erythromycin may be recommended for local therapy of acute mastitis caused by Gram-positive bacteria in lactating dairy cows.     

Involvement of Plasma Progesterone, Oestradiol-17β and Cortisol in Ovulatory Response to Gonadotropin-releasing Hormone in Dairy Cows with Cystic Follicles

The aim of the present study was to examine the plasma concentrations of progesterone, oestradiol-17beta and cortisol in the cows with cystic follicle and to examine its relationship with the ovulatory response to gonadotropin-releasing hormone (GnRH). Eighty-five post-partum Holstein-Friesian cows with cystic follicles regardless of the presence of corpus luteum were studied. Follicular size, presence of corpus luteum and occurrence of ovulation were checked by palpation per rectum. Blood collection and palpation per rectum were conducted on days 0, 7 and 14. Gonadotropin-releasing hormone was administered at day 7. Plasma concentrations of progesterone, oestradiol-17beta and cortisol were determined. Progesterone concentrations of <3.2, 3.2-4.8 and >4.8 nmol/l were defined as low, intermediate and high, respectively. Sixty-three (74.1%) of 85 cows showed low (<3.2 nmol/l =1 ng/ml) progesterone concentrations on day 0. Only 40 (47.1%) of them showed low-low pattern of progesterone at days 0 and 7. In 27 (31.8%) of them, progesterone concentration had increased by day 14. Of 22 cows having high progesterone concentration (>/=4.8 nmol/l) on day 0, corpus luteum was not detected in 18 cows (21.2%). Only in 10 cows, cystic follicle disappeared after GnRH administration. However, only one of 27 cows in which progesterone pattern was low-low-high at days 0, 7 and 14 experienced ovulation of the cystic follicle. Significantly lower oestradiol-17beta concentration was found on day 7 in cows showing a low-low-low pattern than a low-low-high pattern of progesterone (43.0 +/- 4.6 vs 55.8 +/- 2.8 pmol/l, p < 0.05). There was no significant difference in cortisol concentration on any days (days 0, 7 and 14) between cows showing a low-low-low and low-low-high pattern of progesterone. These results suggest that approximately one-fifth of cows diagnosed to have ovarian cysts possess luteal cysts and that a high oestradiol-17beta concentration at the time of GnRH administration is involved in the subsequent ovulation of the follicle, although ovulated follicle may not be cystic.     

Application of an ELISA Milk Pregnancy Test in Beef Cows

Pregnancy‐associated glycoproteins (PAG) are secreted by the binucleate giant cells of the ruminant placenta and enter maternal circulation at the time of placental attachment. The IDEXX Milk Pregnancy Test (IDEXX, Westbrook, ME) detects a subset of PAG in milk. Although designed as a management tool for dairy cows, there is potential for using the milk PAG test in beef cows. Our objective was to compare the performance of the milk PAG ELISA with a gold standard method for pregnancy diagnosis and determine the agreement between milk and serum PAG analysis in lactating beef cows. Angus and Angus‐crossed cows (n = 332) from two Michigan beef herds were enrolled in this study. Cows were subjected either to timed artificial insemination followed by exposure to a bull or exclusively exposed to a bull. The bulls and cows were separated 30 days prior to examination. Serum and milk samples were collected and submitted within 24 h of collection to a commercial laboratory for PAG analysis using the IDEXX Milk Pregnancy Assay (milk) and the IDEXX Bovine Pregnancy Assay (serum). Concurrently with milk and serum collection, each cow was examined transrectally by palpation or ultrasonography. When compared to transrectal examination, the performance (and 95% confidence intervals) of the milk PAG ELISA was sensitivity of 99.7% (99.0–100.0%) and specificity of 80.8% (65.6–95.9%). The lower specificity is likely due to the low prevalence (9.9%) of open cows (n = 30) in the herds examined. Of the 332 cows examined, 1.8% (n = 6) were classified as rechecks using the milk PAG ELISA. Results of the milk and serum PAG ELISA were in high agreement (kappa coefficient = 0.91). The milk PAG ELISA was accurate in predicting pregnancy status using milk collected from beef cattle between days 37 and 125 post‐insemination and may be useful for aiding management decisions in beef herds.     

孕酮免疫生物传感器在奶牛上的临床应用

为了解孕酮免疫生物传感器的临床应用效果,本试验对7头妊娠奶牛,8头产后发情奶牛和18头乏情奶牛的血浆雌二醇、促黄体素、促卵泡素和孕酮浓度进行了检测,同时应用的孕酮免疫生物传感器进行了乳汁孕酮检测。结果显示,孕酮免疫生物传感器检测的乳汁孕酮水平与ELISA检测血浆孕酮含量之间呈正相关。该优化的生物传感器检测奶牛妊娠的孕酮浓度范围为10~15 ng/mL,发情的孕酮浓度范围为4~10 ng/mL;持久黄体的孕酮浓度范围为10~16 ng/mL,卵巢静止的孕酮浓度范围为3~7 ng/mL,黄体囊肿的孕酮浓度范围为12~18 ng/mL。表明该孕酮免疫生物传感器能有效的检测奶牛妊娠、发情和繁殖障碍疾病的乳汁孕酮水平。     

Improved Detection of Reproductive Status in Dairy Cows Using Milk Progesterone Measurements

This study tested a model for predicting reproductive status from in-line milk progesterone `measurements. The model is that of Friggens and Chagunda [Theriogenology 64 (2005) 155]. Milk progesterone measurements (n = 55 036) representing 578 lactations from 380 cows were used to test the model. Two types of known oestrus were identified: (1) confirmed oestrus (at which insemination resulted in a confirmed pregnancy, n = 121) and (2) ratified oestrus (where the shape of the progesterone profile matched that of the average progesterone profile of a confirmed oestrus, n = 679). The model detected 99.2% of the confirmed oestruses. This included a number of cases (n = 16) where the smoothed progesterone did not decrease below 4 ng/ml. These cows had significantly greater concentrations of progesterone, both minimum and average, suggesting that between cow variation exists in the absolute level of the progesterone profile. Using ratified oestruses, model sensitivity was 93.3% and specificity was 93.7% for detection of oestrus. Examination of false positives showed that they were largely associated with low concentrations of progesterone, fluctuating around the 4 ng/ml threshold. The distribution of time from insemination until the model detected pregnancy failure had a median of 22 days post-insemination. In this test, the model was run using limited inputs, the potential benefits of including additional non-progesterone information were not evaluated. Despite this, the model performed at least as well as other oestrus detection systems.     

Laparoscopic intra-uterine insemination of fallow deer with frozen-thawed or fresh semen after synchronisation with CIDR devices

This study investigated the efficacy of fixed-time laparoscopic intra-uterine insemination of farmed fallow deer (Dama dama) with frozen-thawed or fresh semen. In the trials with frozen-thawed semen, a total of 547 mature non-lactating does across five New Zealand farms were used. For oestrous synchronisation and artificial insemination, a standard control regimen was applied to at least 30% of the does on each farm, involving the insertion of single CIDR type-G devices intravaginally for 14 days, deposition of 50 x 10(6) frozen-thawed spermatozoa at 65 hours after withdrawal of the CIDR device and the continuous presence of vasectomised bucks from the insertion of the CIDR device until 10 days after insemination. Various aspects of this protocol were changed for the remaining does on each farm, including inseminations at 60 or 70 hours, the absence of vasectomised bucks, insemination with 25 x 10(6) or 10 x 10(6) spermatozoa, synchronisation with CIDR type-S devices and synchronisation with prostaglandin. The conception rate, based on rectal ultrasonography at 45 days after insemination, was 67% across all treatments (n=547). Corrected conception rates (+/-s.e.), calculated following between-farm adjustments, were 67+/- 3% for the control regimen, 67+/- 9% and 73 +/- 8% for inseminations at 60 and 70 hours respectively, 61 +/- 9% for absence of bucks, 80 +/- 8% and 74 +/- 9% for inseminations with 25 x 10(6) and 10 x 10(6) spermatozoa respectively, 62 +/- 10% for CIDR type-S device synchronisation, and 49 +/- 10% for prostaglandin synchronisation. Despite apparent differences, none of the treatments resulted in adjusted conception rates that were significantly different from the control regimen (P>0.01). In the trials with fresh semen, 216 does in the USA were inseminated at 69-71 hours after withdrawal of the CIDR device using either cryopreserved semen from New Zealand (n=158; 25 x 10(6) spermatozoa per inseminate) or fresh semen (n=58; 7.5 x10(6) to 20 x 10(6) spermatozoa per inseminate) collected less than 10 hours earlier. The overall conception rates were 77% and 81% respectively, with no significant differences between semen type (frozen v. fresh) or fresh spermatozoa number per inseminate (P>0.01). A further 102 does in New Zealand similarly received fresh semen from 3/4 Mesopotamian buck. Doses of 10 x 10(6) (n=35), 5 x 10(6) (n=32) or 2.5 x 10(6) (n=35) spermatozoa per inseminate were delivered at 69-71 hours after withdrawal of the CIDR device. The conception rates were 77%, 66% and 51% respectively, reflecting a dose effect (P<0.05). However, 1/4 Mesopotamian does in the group (n=19) exhibited higher conception rates (95% overall) irrespective of semen dose, possibly indicating a semen/recipient genotype interaction. It is concluded that laparoscopic intra-uterine insemination of fallow deer with frozen-thawed or fresh semen at fixed intervals after removal of a CIDR device can give acceptable conception rates under a range of on-farm management options and semen doses.     

Prevalence of Mastitis Pathogens Preceding and Following Parturition in Primiparous Beef Cows

Prevalence of intramammary infection was studied in primiparous beef cows preceding and following parturition. Aseptic mammary quarter samples were collected from Brahman-sired cows (Group 1; n = 19) on d −143, −30, and 110 ± 4 from parturition, and from Angus-sired cows (Group 2; n = 54) on d -36 and 37 ± 2 from parturition. In Group 1, 67.6, 55.6, and 9.3% of quarters sampled were infected with mastitis pathogens on d −143, −30, and 110 ± 4 from parturition, respectively. In Group 2, 35.3 and 10.4% of the quarters were infected on d −36 and 37 ± 2 from parturition, respectively. In Group 2, over 22% of the quarters that had previously been infected with Staphylococcus aureus, and over 26% of the quarters that had previously been infected with Staphylococcus species were still infected with the same organism on d 37 ± 2 postpartum. In Group 2, representative cows were selected for blood chemistry analyses (n = 30) and machine milking (n = 46). Serum potassium was higher (4.64 vs 4.36 ± 0.09 mmol/L; P<0.03) and serum chloride was lower (106.19 vs 107.24 ± 0.31 mmol/L; P<0.02) in infected than in non-infected cows, respectively. Based on the d 37 ± 2 postpartum milk yield, cows were retrospectively divided into a low-milk (below the median milk production) or high-milk (above the median milk production) group. Serum cholesterol was higher in high-milk than in low-milk cows (145 vs 124 ± 5.3 mg/dL; P<0.01). In summary, mastitis-causing pathogens were present in quarters of primiparous beef cows prior to parturition; however, prevalence was considerably lower during lactation.     

Evaluation of Subclinical Endometritis and Consequences on Fertility in Piedmontese Beef Cows

Subclinical endometritis (SEM) is poorly investigated in beef cows, as stated in the literature. This project aims to evaluate the rate and the consequences of SEM in Piedmontese cows, with a focus on bacteriological findings and fertility parameters. Uterine cytology was performed for 97 subjects; a total of 31% of the cows were diagnosed as being positive for SEM and as having an 8% neutrophil (PMN) presence on the slide, which is considered as the best cut‐off to diagnose the pathology. Only 13% of the cows positive for SEM were pregnant within 130 dpp and generally showed increases of 40 days in the partum to conception interval compared with the negative cows (142 vs 182, p = 0.01). Cows positive for both bacteriology and cytology showed a lower fertility than cows with only inflammation or only a bacterial presence (p = 0.0004). Bacterial isolation detected different species, but no difference in regard to the impact of these bacteria on SEM was shown. Parity, presence of calves, hygiene condition, age and number of service did not affect whether a cow was positive for subclinical endometritis (p < 0.05). The housing system (free stalls vs tie stalls) used seems to affect the SEM rate in Piedmontese cows; cows bred in tie stalls were more likely to be positive for SEM (OR = 2.2; p = 0.04). In conclusion, cytology seems to be a good technique for the diagnosis of subclinical endometritis in beef cows, and as in dairy cows, subclinical endometritis has a detrimental effect on fertility, causing an increase in partum to conception and a decrease in the rate of cows who become pregnant within 130 dpp, particularly for those cows housed in a tie stall.     

Oestrus Expression and Ovarian Function in Repeat Breeder Cows, Monitored by Ultrasonography and Progesterone Assay

Ovarian ultrasonography and plasma progesterone levels were monitored in 37 lactating Holstein cows with a history of repeat breeding; the data obtained were analysed in conjunction with clinical and behavioural signs, to identify the aetiology of the syndrome. Differences were detected between RBCs displaying apparently normal cycles and others with irregular cycles. There were also differences in heat expression; a large number of repeat breeder cows (RBCs, 50%) displayed delayed or silent oestrus. Ovarian disorders were common in RBCs, and included ovarian cysts, mistimed AI, subluteal progesterone levels, luteal dysfunction or ovulation defects. Both ultrasonography and plasma progesterone assays are useful tools for ascertaining the aetiology of the repeat breeder syndrome.     

Cholinesterase Levels in Blood Plasma and Erythrocytes from Calves,Normal Delivering Cows and Cows Suffering from Parturient Paresis

Plasma cholinesterase (pChE) levels and erythrocyte acetylcholinesterase (eAChE) levels were studied in 6 cows before, during and after parturition (Group I), their calves (Group II), 38 cows suffering from parturient paresis (Group III) and 14 newly delivered non-paretic cows (Group IV).The mean of the pChE level in Group I was 1.5 μkat/1 ± 0.20 before parturition and decreased significantly (P ≦ 0.05) to 1.2 ukat/1 ± 0.16 after parturition. The eAChE level was before parturition ≅ 140 ukat/1 and decreased to ≅ 130 μkat/1 4–5 weeks after parturition.At birth the pChE level was 12.8 ukat/1 ± 5.9 in Group II. After 4 weeks the level had decreased to 2.3 ukat/1 ±0.3. In the bull calves the pChE level started to increase when they were 6 weeks old and reached a level of 5.7 μkat/1 ± 0.6 before slaughter at 6 months of age. The heifers did not show this increase. They had a level of around 2 μkat/1 throughout the investigation. The eAChE level at birth was 119 μkat/1 and increased slowly to a level of 145 μkat/1 at 6 months. No differences between the sexes were found.The cows suffering from parturient paresis had a pChE level of 1.80 μkat/1 ± 0.30 before treatment with calcium (Ca). The level decreased significantly (P ≦ 0.001) after Ca-infusion to a level of 1.67 ukat/1 ±0.29. Group IV had a pChE level of 1.65 μkat/1 ± 0.42 at parturition. Two to 4 months later the cows that had recovered from milk fever had a level of 1.61 μkat/1 ± 0.31 and the control cows 1.66 ukat/1 ± 0.48. No differences between the groups were found for the eAChE level.The findings show that parturition influences the pChE level in cows and that sex influences the pChE level in calves between 6 weeks to at least 6 months of age. Furthermore the elevated pChE level found in the cows suffering from parturient paresis before Ca infusion may be a further sign of a disturbance in the cholinergic system with a special preference to the neuromuscular junctions.     

Clinical Response in Anestrous Dairy Cows with High or Low Blood Progesterone Levels to Treatment with the PGF Analog Alfaprostol*

Contents: In a controlled field trial, 211 anestrous dairy cows with palpable corpora lutea were treated once with a luteolytic dose of the PGF analog alfaprostol (1.5 mgl 100 kg bw) or with a placebo solution. In cows not responding with heat within 10 d, the same treatment was repeated. All cows showing heat were bred. Blood progesterone values were determined at the days of treatment, 2 or 3 d thereafter and at breeding. As reported previously, 109 of 199 cases available for final evaluation showed initially high progesterone values (>6.36 nmol/L) and responded to one or two treatments with heat (alfaprostol us placebo: 96.6% us 48.0%). Breeding resulted in an overall pregnancy rate of 71.4% us 3 7.2%. Of the ninety cows showing initially low blood levels of progesterone (<6.36 nmol/L), 93.5% responded to the first or second alfaprostol treatment with heat versus 27.3% of the placebo treated controls. Breeding of these cows resulted in an overall pregnancy rate of 69.6% (alfaprostol) us 27.3% (placebo). Cows with low progesterone levels treated with alfaprostol once or twice responded with a higher level of heat than anticipated from silently cycling animals. This indicates that the well described gonadotropin releasing effects of PGF in cattle may have resulted in the stimulation of follicular growth, followed by overt or covert estrus, ovulations, conceptions and the formation of corpora lutea. Inhalt: Klinische Ergebnisse der Behandlung mit einem Prostaglandin F Analog, Alfaprostol, bei Milchkühen mit hohem oder niedrigem Blutprogesteronspiegel In einem doppelten Blindversuch erhielten 211 anöstrische Milchkühe, die ein palpier-bares Corpus luteum aufwiesen, eine luteolytische Behandlung mit 1.5 mg/100 kg KGW des PGF Analogs Alfaprostol oder eine Plazeboinjektion. Bei Kühen, die innerhalb von 10 Tagen keine Brunst erkennen lieβen, wurde diese Behandlung wiederholt. Alle Kühe, die in Brunst kamen, wurden besamt. Blut für Progesteronbestimmungen wurde am Tag der Behandlung, am 2. oder 3. Tag danach und am Tag der Besamung entnommen. Serumprogesteron wurde rnit einem RIA bestimmt. Wie schon früher berichtet, wiesen 109 von 199 Fällen, die zur Endauswertung zur Verfügung standen, am Tage der Behandlung einen hohen Progesteronwert auf (<6.36 nmol/L) und reagierten auf die 1. oder 2. Behandlung mit Brunst (Alfaprostol : Plazebo=96.6% : 48%). Die Besamung resultierte in einer Trächtigkeitsrate von 71% für Alfaprostol und von 37.2% für Plaze-bobehandlung. Von den 90 anöstrischen Kühen rnit niedrigem Progesteronwert bei Behandlungsbeginn (<6.36 nmol/L) reagierten 93.5% mit Brunst auf die 1. oder die 2. Behandlung mit Alfaprostol, aber nur — wie zu erwarten — 27.3% der mit Plazebo behandelten Tiere; 69.6% (Alfaprostol) und 27.3% (Plazebo) wurden tragend. Kühe mit niedrigem Progesteronspiegel reagierten somit auf die PGF-Behandlung, entgegen den Erwartungen, ebenso mit einem hohen Prozentsatr an Brunst und nachfolgender Konzeption. Es ist bekannt, daβPGF bei Kühen Gonadotropine freirusetzen vermag. Dieser Effekt könnte für die Anregung von Follikelwachstum, Brunst oder Stillbrün-stigkeit, Ovulation, Konzeptionen und die Bildung von Gelbkörpern verantwortlich gemacht werden.     

Absence of Feeding-Induced Variations in Plasma Insulin in Hypoglycaemic-Ketonaemic Cows

The effects of food intake on plasma insulin levels were studied in 38 cows with plasma sugar ranging from 41 to 86 mg/100 ml and acetoacetate (Acac) ranging from 0.2 to 18 mg/100 ml, measured before morning feeding. The animals were fed concentrates, silage and hay. Blood samples were taken immediately before feeding in the morning and at intervals of % to 1 hr. during the following 4 hrs.In animals with low blood Acac, plasma insulin concentrations began to increase as early as 1/2 hr. after the start of feeding and reached maxima after 2 hrs. Simultaneously Acac increased and sugar decreased markedly. Animals with Acac levels > 1 mg/100 ml had low pre-feeding insulin concentrations, and the level of the hormone did not increase after feeding. They did not show systematic changes in Acac. But plasma sugar tended to decrease when food was given, even in the absence of insulin increments in peripheral blood.Glucose was infused at a low rate (0.9 g/min.) for 18 hrs. into a hypoglycaemic, ketonaemic cow. As her glucose and ketone levels became normalized, she also responded to feeding with insulin increments. But throughout the experiment her plasma insulin remained considerably lower than in an identically treated control animal which had low Acac levels before the infusion. It appears that the endocrine adjustments during ketonaemia in cows include, beside low basal (pre-feeding) insulin levels, an inhibition of the normally occurring elevation of plasma insulin after feeding.