The relationships among palpator experience, milk progesterone concentration and estrus and fertility in cows with palpable corpora lutea treated with cloprostenol

Two hundred and fifty-one cows fresh at least 37 days with normal reproductive tracts and palpable ovarian structures which clinicians believed to be corpora lutea and which were presumed to be producing progesterone were treated with 500 micrograms of cloprostenol. The cows were stratified into three groups based on milk progesterone concentrations in whole milk samples taken at the time of examination. The low group had milk progesterone concentrations less than or equal to 1 ng/ml, the intermediate group had milk progesterone concentrations between 1 and 3 ng/ml, and the high group had milk progesterone concentrations greater than or equal to 3 ng/ml. The proportion of cows in each group inseminated within 5 days of treatment and the fertility at that breeding were compared. There were no significant differences among the groups with respect to the proportion of cows that came into estrus within 5 days. However, the conception rate of the high group (54%) was significantly greater than that of the intermediate group (26%). To study the relationship between practitioner experience and diagnostic accuracy the proportion of cows with low, intermediate and high concentrations of progesterone selected by clinicians with more than 3 years experience was compared to that for clinicians with 3 years of experience or less. Less experienced clinicians were significantly more likely to make a false positive diagnosis of functional luteal tissue in cows with palpable ovarian structures than were more experienced clinicians.     

Relationships between the conception rate of estrus synchronization using estradiol benzoate and CIDR (progesterone) and other parameters in holstein lactating dairy cows

The purpose of this study was to determine the relationships between conception rate and other parameters before estrus synchronization with a Controlled Internal Drug Release Device (CIDR) and estradiol benzoate (EB). In the estrus synchronization program, animals were injected with 2 mg EB and then received a CIDR. Seven days later, the CIDR was removed and the animals were given an injection of Prostaglandin F(2alpha). Twenty-four hours later, they received an injection of 1 mg EB, and they were artificially inseminated 24 h after that. This program was applied to 258 Holstein cows in Tohoku-machi (Aomori, Japan). Blood was collected at the beginning of the program, and the conception rate was determined about 40 days after insemination. The relationships among conception rate, blood biochemical values, age, body condition score and days in milk were statistically analyzed to determine better conditions for cow conception. The conception rate of the cows in the high progesterone group (more than 1 ng/ml, P(4)+) was significantly higher than that of the low progesterone group (less than 1 ng/ml, P(4)-; 47.9% vs. 28.6% P<0.01). In the P(4)- groups, the serum phospholipid level was significantly higher in the conception group than in the non-conception group, and the same tendency was seen in the P(4)+ groups. Blood urea nitrogen (BUN), albumin (Alb), and total cholesterol (TChol) were significantly higher in the conception group compared with the non-conception group, but no with P(4) was observed. We concluded that 1) the conception rate of the P(4)- group was remarkably low, that 2) the low conception rate and low P(4) level was related to a low PL level and that 3) BUN, Alb and TChol were higher in the conception group, although no relation with P(4) was found.     

Prostaglandin F2 alpha-induced estrus in open cows and presumed abortion in pregnant cows with unobserved estrus in a herd monitored by milk progesterone assay

Data were obtained in a large Florida herd of about 1800 Holstein cows. All cows were inseminated by the herdsman who did the pregnancy checks and who also administered drugs. The herdsman injected 103 cows with prostaglandin F2 alpha during the time this herd was under continuous observation by the authors who were conducting an unrelated research project. These cows consisted of 86 open (never bred) cows which had no estrus observed during the first 70 days postpartum, or no second estrus observed within 30 days after a previous estrus, and 17 cows previously inseminated. Two-thirds (57) of the 86 open cows were in estrus within 4 days. The 17 previously inseminated cows appeared to be pregnant, based upon progesterone profiles, when these were inadvertently given prostaglandin F2 alpha by the herdsman. Progesterone declined in all cows and they were in estrus in 7 +/- 4 days (mean +/- standard error). This result of presumed abortion reflects the luteolytic effectiveness of the drug and the importance of instructing any laymen users to follow necessary precautions to avoid undesirable effects.     

Histology of the oviduct epithelium of dairy cows after estrus synchronization with cloprostenol

After fading away of the effect of cloprostenol contained in the Oestrophan inj. Spofa preparation, the qualitative and quantitative changes in the epithelium of oviduct ampulla and isthmus of dairy cows were studied. Three dairy cows in the fourth to fifth day after heat were used as control, three cows with the rectally palpated active corpus luteum were given 0.5 mg cloprostenol i. m. On the eighth day after treatment, samples were taken from ampulla and isthmus by means of necropsy. After histological treatment, the samples were evaluated microscopically. Histological staining with hematoxylin-eosine, PAS reaction and PAS reaction with nucleus staining with Harris hematoxylin were used to describe the occurrence of the so-called pale cells. In accordance with the literary data, these cells are believed to be intraepithelial lymphocytes, the function of which will have to be further researched and determined objectively. On the eighth day after cloprostenol administration or on the fourth to fifth day after ovulation in the ipsilateral ovary, a significant decrease in epithelium thickness close to infundibulum and in the depth of ampulla (P less than 0.001) was observed. The changes in the contralateral left side were not significant. After cloprostenol application, the multiplication of nail-like cells in the right-side oviduct ampulla was statistically significant (P less than 0.05).     

Evaluation of oestrus observation and conception rates in suckling beef cows using whole milk progesterone concentration

A 2-sample regime was used to measure whole milk progesterone concentration on the day of oestrus and insemination (Day 0) and 6 days later (Day 6) in a sample of 50 primiparous and 100 multiparous suckling beef cows. Exposure to teaser bulls and observation by cattlemen identified the occurrence of oestrus. Three sets of criteria used to define ovulatory oestrus were compared: a) milk progesterone concentration less than 6 nmol/l on Day 0; b) milk progesterone less than 6 nmol/l on Day 0 and rising to greater than 6 nmol/l on Day 6; c) milk progesterone less than 6 nmol/l on Day 0 and rising to greater than 6 nmol/l on Day 6, or cow diagnosed pregnant to 1st insemination. Using only a single milk sample on Day 0 (criterion a) would have resulted in the positive predictive value of heat detection being estimated at 98.7%. Using a pair ed measurement (criterion b) resulted in a significantly lower estimate of 84.7%. The inclusion of cows that conceived despite not showing a marked rise in milk progesterone concentration (criterion c) resulted in a more accurate estimate of 89.3 %. Use of a 2-sample regime also allowed calculation of conception rates while eliminating the effect of heat detection errors. In the cows sampled, of those in ovulatory oestrus that were inseminated, 73.1% conceived to the 1st insemination. These results demonstrate that artificial insemination within a limited breeding season can be successful if nutrition is optimal and management is intensive. The use of a 2-sample milk progesterone test may be a valuable tool in investigating heat detection and conception problems in beef herds in which artificial insemination is used.     

注射国产LRH-A对产后母牛卵巢活动、发情和受胎的作用

<正> 引言 促性腺激素释放激素(GnRH)是下丘脑神经内分泌细胞分泌的一种释放激素。由于本身结构和功能上的特点,自七十年代初人工合成后,GnRH及其类似物被广泛用于牛繁殖的研究和生产中。国外有报道认为GnRH有促进产后母牛发情周期恢复,缩短产后空怀天数等作用。国内用LRH-A提早牦牛产后发情和受胎收到良好效果。     

Superovulation and uterine lavage in relation to subsequent conception in donor cows

On the Slusovice co-operative farm, embryo transfer has been practised since 1984 as a method of controlled reproduction of the heifer and cow herd. The effect of superovulation, embryo recovery and administration of 500 micrograms Oestrophan Spofa upon the donors' conception rate and upon their resuming a new reproduction cycle was studied on this farm. The effect of superovulation, induced by FSH-P (Folicotropin, Spofa), was evaluated in 162 cows, out of which 121 (74.69%) got in calf after three inseminations. Fifty-nine (48.76%) of the pregnant cows got in calf after the first insemination, 38 (31.40%) after the second insemination, and 24 (19.83%) after the third insemination. Having been subjected to embryo collection and luteolysis, the donors conceived within 67.6 days, on an average, and the animals superovulated within 60 days post partum conceived within 59.11 days. The average SP of the superovulated animals was about 148 days but in the donors from which the embryos had been recovered within 60 postpartal days the SP did not exceed 110 days. Hence the earlier postpartal superovulation of cycling cows speeds up the resumption of reproduction in the donors and increases the numbers of recovered embryos. Repeated superovulation had no influence on the fertility of the cows but adequately prolonged the service period.     

Plasma progesterone and gonadotrophin concentrations following norgestomet treatment with and without cloprostenol in beef cows

Twelve Hereford cross Friesian cows received subcutaneous implants containing 6 mg norgestomet and intramuscular injections of 5 mg oestradiol valerate and 3 mg norgestomet. Six of the cows also received 0.5 mg cloprostenol eight days later and all implants were removed on day 9. When treatment was commenced between days 3 and 5 of the ovarian cycle, luteal function was not prevented although the luteal phase was shortened in some cases. When treatment was commenced between days 8 and 14 of the cycle progesterone concentrations remained above basal levels for five to seven days. Cows with corpora lutea that were given cloprostenol underwent rapid luteolysis. It is concluded that oestradiol valerate does not control luteal function adequately, particularly if administered early in the cycle, and this may explain failure of oestrus synchronisation in some cases. Administration of prostaglandin 24 hours before norgestomet implant removal may improve the degree of oestrus synchronisation in groups of cyclic cows.     

Changes in plasma progesterone concentrations in mares treated with cloprostenol and human chorionic gonadotropin and inseminated during estrus

Daily changes in the plasma progesterone concentrations were determined in eight mares treated with intramuscular injections of 250 μg cloprostenol, a prostaglandin analogue, followed five days later by 2500 I.U. human chorionic gonadotropin. A second cloprostenol injection was given 14 days after the first; the mares were then inseminated on the third and fifth day of the subsequent estrus and a second injection of human chorionic gonadotropin was administered on the fifth day. The onset of estrus following the second cloprostenol treatment was synchronized beginning three to four days after treatment in all eight mares. All eight ovulated, five mares conceived and only four foaled. Evaluation of the progesterone profiles provided reliable indicators of luteolysis, ovulation and luteal function. Decreasing plasma progesterone concentrations were associated with cloprostenol induced luteolysis or preceded spontaneous onset of estrus. The plasma progesterone concentrations increased consistently after ovulation, and in the pregnant mares, the progesterone concentrations remained high during the first month after insemination.     

A field study on the usefulness of milk progesterone determination to confirm estrus and pregnancy of dairy cows in the Fraser Valley area of British Columbia

A field study was conducted to determine the usefulness of milk progesterone determination at the time of breeding to confirm estrus and at 21 days postbreeding to detect open cows. Twenty-seven dairy farmers collaborated in this study by providing milk samples on the day of breeding and 21 days later, together with pregnancy diagnosis data and information on herd reproductive management. Herd size ranged from 15 to 175 cows, the average being 65 milking cows. Six hundred and sixty-seven breeding-day samples and 472, 21-day samples were provided by the farmers. Analysis of milk samples for progesterone by a solid phase radioimmunoassay showed that only 32 (4.8%) of the services were performed when the cow was not in estrus (progesterone > 1 ng/mL). Of the 472, 21-day samples, 337 (71%) showed progesterone levels of > 1 ng/mL, while 135 (29%) showed progesterone levels of < 1 ng/mL. Subsequently, 243 (72%) of the cows with progesterone > 1 ng/mL and eight (6%) of the cows with progesterone < 1 ng/mL were diagnosed pregnant by transrectal palpation, giving a pregnancy rate of 53%. Progesterone concentration on the day of breeding was not associated with season or herd size. However, progesterone concentration at 21 days and pregnancy rate were associated with herd size. These results indicate that fertillzation failure and/or early embryonic mortality, rather than inaccurate detection of estrus, are the major reproductive problems encountered by the dairy farmers in British Columbia. Furthermore, progesterone values at 21 days were closely related to reproductive status and indicate the usefulness of milk progesterone assay for the early detection of open cows.     

The use of milk progesterone profiles for assessing the response to cloprostenol treatment of non-detected oestrus in dairy cattle

Post-partum milk progesterone profiles from 1400 dairy cows were used to identify 296 animals which had ovulated 50 or more days post partum without being observed in oestrus. Of these, 165 cows were left as untreated controls, being inseminated at any observed oestrus after 60 days post partum. Fixed time insemination three and four days after a single cloprostenol injection (74 cows) resulted in a short calving-to-conception interval and a lower culling rate than in control cows, while insemination at observed oestrus after cloprostenol (57 cows) resulted in an even greater improvement in these parameters. The fixed-time insemination group required significantly more services per conception than either of the other groups (P < 0.005). A study of the profiles suggested that not all of the cows had ovulated within four days of injection and that those ovulating later had a greater chance of being observed in oestrus and becoming pregnant if insemination was carried out only at observed oestrus after cloprostenol injection.     

The use of milk progesterone analysis to monitor reproductive activity in the camel (Camelus dromedarius)

Milk progesterone profiles were used to monitor the ovarian changes during the post-partum period of five she-camels. Milk samples were collected daily for 60 days from four suckling camels (1-4) and from one animal whose calf died on day 3. Progesterone was determined using the Ovucheck Bovine progesterone kits. The first increase of progesterone level in the five animals occurred on days 28, 26, 21, 24 and 20 respectively. At least two progesterone peaks of 6 +/- 2 SD days' duration occurred during the 60 days. An early one day peak was also noticed in three animals.     

Postpartum interval to estrus and patterns of LH and progesterone in first-calf suckled beef cows exposed to mature bulls

Two trials were conducted in which Angus x Hereford first-calf cows were assigned randomly at calving to one of two treatments: exposure to mature penile-blocked bulls (BE) or isolation from bulls (NE). In Trial 1 (BE, n = 38; NE, n = 37), cow to bull ratio increased from 12:1 to 19:1 over a 14-d period; in Trial 2 (BE, n = 25; NE, n = 24), this ratio was maintained at 13:1. In both trials, blood samples were collected weekly for progesterone and ovaries and uteri of cows were examined rectally. Cows were observed for estrus twice daily (am:pm) beginning 10 d after calving. In Trial 2, intensive blood sampling for LH began 10 d after calving (eight cows per treatment) and continued at weekly intervals until estrus or the end of the trial. Postpartum weight change, condition score change and time to uterine involution did not differ (P greater than .10) between treatments in either trial. Interval to estrus was shorter (P less than .05) for BE cows than for NE cows in both trials. A greater proportion (P less than .05) of BE cows exhibited estrus by 60 and 90 d after calving and showed an increase in progesterone before first estrus. Mean and baseline LH concentrations and amplitude, frequency and duration of LH pulses were not altered (P greater than .10) by bull exposure. In conclusion, exposing first-calf suckled beef cows to bulls after calving hastened resumption of estrous cycles. Bull exposure did not alter patterns of LH concentrations but did increase proportions of cows that showed increased progesterone before first estrus.     

Elimination of erythromycin in milk after intramammary administration in cows with specific mastitis: relation to dose,milking frequency and udder health

Elimination of erythromycin in milk following intramammary therapy of specific mastitis in cows was studied. Five cows received therapy in one quarter (G1), and eight in two quarters with five milked twice (G2) and three thrice a day (G3). Dose infused was 300 mg/quarter 12 h × 5 times. The drug concentrations in milk were determined using microbial assay technique with Micrococcus luteus as the test organism. Considerable variations occurred in the excretion of drug; levels for treated quarters being 8.25 to 37.61 μg/ml at first milking that declined rapidly at 24 h and no drug activity was observed beyond 36 h post treatment. In total, about 6–25% of the last infused dose appeared in the milk. Drug crossed to 1/15 quarter (G1), 6/10 quarters (G2) and all the six untreated quarters (G3). Crossover levels were significantly higher in mastitic quarters and for G3 cows, but duration of excretion remained same in all cases. It seems that crossover of erythromycin to untreated quarters is related to the udder health and dose infused.