Determination of ovulation time in bitches based on teasing, vaginal cytology, and elisa for progesterone.

The estrous cycle of 16 mature mongrel female dogs was monitored to evaluate the accuracy of teasing, vaginal cytology and quantitative ELISA progesterone assay to determine ovulation. The dogs were presented to male, and blood samples and vaginal swabs were taken daily during proestrus and estrus. Selected serum samples collected during estrus were assayed for endogenous LH by radioimmunoassay (RIA). Plasma samples collected during proestrus and estrus were assayed for progesterone with a commercially available ELISA kit. Ovulation was considered to take place 48 h after the preovulatory LH peak. Vaginal cytology smears were stained with Wright's stain and evaluated for the percentage of superficial squamous cells. Day 1 of diestrus (Day 1) was defined as a drop of 20% or more in the total number of superficial cells. Two standard curves (linear and best fitted curves) commonly used with ELISA were compared together and with the RIA progesterone assay. Ovulation was estimated to occur when progesterone concentration was 4.9 +/- 1.0 ng/ml (mean +/- SD, n = 15), with a range of 3.4 to 6.6 ng/ml. Based on vaginal cytology, ovulation took place 6.9 +/- 1.6 d (n = 15) after 80% of the squamous cells were superficial and 6.8 +/- 1.4 d (n = 16) before Day 1. Ovulation took place 2.1 +/- 3.9 d (n=11) after the first day of standing estrus and 8.8 +/- 1.5 d (n = 10) before the last day of receptivity. The two standard curves were found parallel to each other and to the RIA progesterone assay. Based on the results of the present study, ELISA progesterone assay and determination of the first day of estrus by vaginal cytology are reliable methods for predicting ovulation, whereas the last day of receptivity as determined by teasing and Day 1 as determined by vaginal cytology are reliable methods to retrospectively estimate ovulation time.

Characterization of the caprine estrous cycle using enzyme immunoassay for the determination of whole blood progesterone concentration.

Eighteen mature female dairy goats were used to determine the feasibility of enzyme immunoassay for the measurement of progesterone in this species. Both quantitative and qualitative enzyme immunoassay kits were used to measure progesterone concentration in unextracted whole blood. Progesterone profiles were similar to those previously reported using either protein-binding or radioimmunoassay as the test. A Pearson's correlation coefficient comparison of our enzyme immunoassay values with radioimmunoassay values gave a correlation coefficient of 0.95. Using the qualitative test, 100% of the samples with high progesterone concentrations had quantitative values greater than 4.00 ng/ml progesterone with a mean of 12.13 ng/ml. Estrus samples had a mean progesterone concentration of 0.70 ng/ml.

Influence of dystocia on white blood cell and blood neutrophil counts in mares.

A retrospective study was done on total white blood cell (WBC) and blood neutrophil counts of 41 mares referred to one of two veterinary hospitals for correction of dystocia. The mares were 2 to 19 years of age and included draft, light, and pony breeds. The WBC and neutrophil counts were performed at varying intervals from time of admission to 10 d after delivery of the feti. Retrospective analyses of WBC and neutrophil counts from 10 normal foaling mares from two Pennsylvania breeding farms (Thoroughbred and Trakehner) and from 14 normal foaling pony mares were done as controls. Mean WBC (10446 +/- 2296 cells/mul) and neutrophil (6850 +/- 2136 cells/mul) counts on the day of delivery in mares with normal parturition were slightly elevated over values reported as normal in the literature. The mean blood cell counts gradually declined to 6124 +/- 1255 WBC/mul and 3692 +/- 409 neutrophils/mul on Day 2 postpartum and returned to normal baseline values by Day 3 postpartum (8868 +/- 2693 WBC/mul, 4298 +/- 1966 neutrophils/mul). No toxic neutrophils were present in mares with normal delivery. Mean WBC (11346 +/- 3298 cells/mul) was elevated on the day of delivery in mares with dystocia as a result of neutrophilia with a left shift (9297 +/- 3298 neutrophils/mul). An apparently faster decline occurred in WBC and neutrophil counts of mares with dystocia than in mares with normal delivery, until a marked leukopenia (3905 +/- 1292 WBC/mul) and neutropenia (1570 +/- 1340 neutrophils/mul) occurred on Day 3 postpartum. The leukopenia and neutropenia persisted until Day 5 postpartum. Toxic neutrophils were present in several mares with dystocia.

Scrotal circumference adjustment for differences due to age of beef bulls.

Scrotal circumference measurements on 870 Angus, 759 Polled Hereford, and 309 Simmental bulls ranging in age from 484 to 704 days were analyzed to develop an appropriate method of adjustment of scrotal circumference for differences associated with age of the bull. Data were separated by breed, year, and season and then each subset of data was subjected to statistical analysis. Adjustment factors to remove differences due to age were developed for bulls of the three breeds studied.

The effects of stanozolol and boldenone undecylenate on scrotal width, testis weight, and sperm production in pony stallions.

Fifty mature pony stallions were randomly assigned to one of five treatment groups: Group 1- controls (no treatment), Group 2 - 0.55 mg/kg stanozolol weekly for 13 treatments, Group 3 - 1.1 mg/kg stanozolol every 3 weeks for 5 treatments, Group 4 - 1.1 mg/kg boldenone undecylenate every 3 weeks for 5 treatments, and Group 5 - 0.55 mg/kg boldenone undecylenate weekly for 13 treatments. Scrotal widths (SW), combined testis weights (CTW), and daily sperm productions (DSP) were not different between Groups 1 and 2. Ponies in Group 5 had smaller SW (P<0.01), smaller CTW and decreased DSP compared to controls (P < 0.05). Although SW for ponies in Groups 3 and 4 were less than for controls (P < 0.01), CTW and DSP were not different. The only treatment regime that did not alter SW, CTW, and DSP was Group 2 (0.55 mg/kg stanozolol weekly for 13 treatments).

Luteinizing hormone response to estradiol benzoate in cows postpartum and cows with ovarian cysts.

Twenty-seven dairy cows were evenly assigned to one of three groups and given an intramuscular injection of 2 mg estradiol benzoate. Cows in group 1 were greater than 30 days postpartum at treatment and had been diagnosed via rectal palpation to have ovarian cysts. Cows in groups 2 and 3 were 12 to 14 and 30 to 40 days postpartum, respectively. Blood plasma was collected from all cows before treatment and then every three hours for 36 hours post-treatment. Concentrations of LH, estradiol-17 beta and progesterone in plasma were determined by radioimmunoassay. Four, zero and five cows in groups 1, 2 and 3, respectively, had concentrations of progesterone greater than 1.0 ng/ml before estradiol benzoate treatment. None of these cows had a peak LH release greater than 5 ng/ml following estradiol benzoate treatment. The numbers of cows with progesterone concentrations less than 1 ng/ml that released LH (>5 ng/ml) in response to estradiol benzoate were 3 of 5, 3 of 9, and 4 of 4 for groups 1, 2, and 3, respectively; the proportion for group 3 was higher (P<.05) than for group 2. Of the cows that released LH, mean peak LH concentrations were 33.3+/-5.4, 14.8+/-7.2 and 24.6+/-9.8 ng/ml for groups 1, 2 and 3, respectively, and the duration of the LH increase was 8.0+/-1.0, 8.0+/-2.0 and 13.0+/-4.0 hours. The time from estradiol benzoate treatment to peak LH release for cows with ovarian cysts (25+/-2 hours) was delayed (P<.05) compared with that for cows 30 to 40 days postpartum without ovarian cysts (16+/-1 hour). In summary, responsiveness to estradiol benzoate is regained between 2 to 4 weeks postpartum in most cows. In addition, some cows with ovarian cysts can release LH in response to estradiol benzoate, but peak LH release is delayed compared to cows at a comparable stage postpartum without ovarian cysts.

Effect of ovarian activity and endogenous reproductive hormones on GnRH-induced ovarian cycles in postpartum dairy cows.

The objective was to determine the relationship of prior follicular development to GnRH-induced cyclic ovarian activity in dairy cows postpartum. Sixty lactating Holstein and Guernsey cows from the University of Missouri dairy herds were assigned at random to one of two groups. Group I consisted of 20 cows (control) given a single intramuscular (IM) injection of saline. Group II consisted of 40 cows given a single injection of 100 micrograms gonadotropin releasing hormone (GnRH) IM. Treatments were administered 12 to 14 days postpartum. All cows were palpated per rectum to monitor ovarian activity prior to treatment (time 0) and 2 to 3 and 7 to 9 days post-treatment. Blood was collected via tail vessel puncture at time 0 and 7 to 9 days post-treatment. The percentage of cows exhibiting a follicle 10 mm or greater in diameter prior to treatment was not different between Group I (50%) and Group II (43%). However, twenty (50%) of the GnRH-treated cows initiated cyclic ovarian activity following treatment as evidenced by palpable CL and plasma progesterone greater than or equal to 1.0 ng/ml on day 9 post-treatment in contrast to only four (20%) saline-treated cows (P less than 0.05). Seventeen of 20 cows ovulating in Group II exhibited a palpable follicle greater than or equal to 10 mm in diameter prior to treatment compared to 3 of 4 cows in Group I. Prior to treatment, plasma concentrations of LH, estradiol-17 beta and progesterone were not different (P less than .05) between cows in Groups I and II. In Group II, preinjection levels of estradiol-17 beta and LH for cows ovulating in response to GnRH were higher (P less than .01) than in cows not ovulating. Postinjection concentrations of progesterone in plasma on days 7 to 9 were higher (P less than .01) in cows ovulating than in cows not ovulating. Six (30%) cows in Group I developed ovarian cysts prior to conception as compared to 12.5% (5) of the cows in Group II (P less than .05). The present study suggests: (1) GnRH treatment as early as 12 to 14 days postpartum may initiate cyclic ovarian activity in normal dairy cows; (2) elevated preinjection concentrations of estradiol-17 beta and follicular growth are important for GnRH induced ovulations; and (3) GnRH treatment 12 to 14 days postpartum may be useful in reducing abnormal ovarian activity.

Reproductive hormone and ovarian changes in cows with ovarian cysts.

Changes in ovaries and concentrations of reproductive hormones were monitored for 30 days in eight dairy cows with ovarian cysts. Diagnosis of ovarian cysts was based upon detection of single or multiple follicular structures on one or both ovaries of at least 2.5 cm in diameter twice at 10 days apart. Eleven days following the initial diagnosis (day 0) cows were bled at .5-h intervals for 4 h. Beginning the next day eight blood samples were collected from each cow at 4-day intervals. Ovarian examinations were subsequent to blood collection on days 1 to 29. Although concentrations of luteinizing hormone in plasma were variable within cows, only four cows had maximum concentrations greater than 3.0 ng/ml at any time. During the 29 day interval concentrations of progesterone and estradiol-17 beta were not only different among cows but also variable within cows. Over the 29 days, only one cow had mean concentrations of progesterone in plasma greater than 1.0 ng/ml, but concentrations were 1.0 ng/ml or greater in seven of the cows in at least one of the eight plasma samples. Ovarian cycles were not reestablished in any of the cows. However, cystic structures regressed in six cows but only in conjunction with the formation of new ovarian cysts.

Testosterone concentrations in plasma of dairy cows with ovarian cysts.

Testosterone in plasma was measured by radioimmunoassay in cows with ovarian cysts and in cows during the estrous cycle. Concentrations of testosterone in plasma (60.8 +/- 2.7 pg/ml; mean +/- standard error) in cows with ovarian cysts were variable but within the range in cows during the estrous cycle. Mean concentrations of testosterone in plasma increased from 46.3 pg/ml at estrus to 85.1 pg/ml on day 13 of the estrous cycle. In cows with ovarian cysts, concentrations of testosterone in plasma declined within 24 h following prostaglandin F2 alpha and tended to increase by 9 days following gonadotropin releasing hormone. The role of testosterone in estrual behavior and inhibiting resumption of ovarian cycles is likely minimal.

Correlation between pregnancy diagnosis by membrane slip and embryonic mortality.

In a study involving 7,477 pregnant cows (5,426 Holstein-Friesians and 2,051 Guernseys), each pregnancy was diagnosed by rectal palpation, using the membrane slip technique. Each cow was examined twice, first by a veterinary student, then by a clinician. Of the cows diagnosed pregnant, 7,058 (94.4%) calved. The embryonic death rate in cows examined during the first 50 days of gestation was significantly (P less than 0.001) greater than that associated with examinations after 50 days of gestation. A significant difference was found between herds in different years (P less than 0.05). There was no conclusive indication that embryonic loss at the time of or shortly after early examination was iatrogenic abortion resulting from the membrane slip technique.

Reproductive hormones associated with the ovarian cyst response to GnRH.

Eighteen cows with ovarian cysts were administered 100 mug of GnRH and bled prior to treatment, at half hour intervals for 4 hours posttreatment and on days 1, 5 and 9 posttreatment. Blood plasma was analyzed for estradiol-17beta, progesterone and LH by radioimmunoassay. Response to treatment was recorded as positive if ovulation was detected within 30 days posttreatment. Fourteen cows (78%) initiated ovarian cycles by 30 days posttreatment. Mean pretreatment concentrations of estradiol-17beta, progesterone and LH and the GnRH induced LH release were not different for positive or no response cows. However, all seven cows that had pretreatment progesterone concentrations greater than 1.0 ng/ml had a positive response to treatment. Eight of the remaining eleven cows had a progesterone response (mean progesterone concentrations on days 5 and 9 posttreatment) greater than 1.0 ng/ml; seven had a positive response to treatment. In summary, most cows with ovarian cysts administered GnRH will initiate ovarian cycles within 30 days if: 1) pretreatment progesterone concentrations are greater than 1.0 ng/ml or 2) if progesterone response is greater than 1.0 ng/ml.

Reproductive hormones associated with normal and abnormal changes in ovarian follicles in postpartum dairy cows.

Concentrations of reproductive hormones and ovarian changes were monitored every 4 days during the postpartum period in 35 dairy cows. The cows were classified as either control (22 cows) or cystic (13 cows) based on per rectum examination of the ovaries. Control cows were detected with a corpus luteum after the first postpartum ovulation while in cystic cows, ovarian follicles of at least 2.5 cm in diameter persisted in the absence of a corpus luteum for at least 14 days. The mean postpartum interval to the first follicle 1.5 to 2.0 cm in diameter was about 16 days for both groups. Ovulation was detected earlier postpartum for cows in the control group (18.4 +/- 1.7 days) than for cows in the cystic group (36.3 +/- 2.7 days). Luteinizing hormone in plasma increased during the early postpartum period (days 1 to 10) for both groups, but mean concentrations of luteinizing hormone, progesterone, and estradiol-17 beta in plasma were not different between groups then or on days -8, -4, or 0 (day of the first postpartum follicle 1.5 to 2.0 cm in diameter). During this period (days -8 to 0), estradiol-17 beta and luteinizing hormone in plasma were correlated positively, but regression coefficients differed between groups. These results suggest a partial hypothalamic and/or pituitary failure in releasing pituitary luteinizing hormone as a cause for postpartum ovarian cysts.

Concentrations of progesterone in milk as a monitor of early pregnancy diagnosis in dairy cows.

The objectives of the experiment were to evaluate the efficacy of using progesterone concentrations in milk and palpation per rectum on days 21 or 22 postbreeding to estimate pregnancy and evaluate management practices; and to investigate physiological occurrences leading to incorrect diagnosis of pregnancy when serial samples of milk were collected. Of particular interest were indications of early embyronic death and insemination of cows not in estrus. Milk samples were collected at the afternoon milking of days 0 or 1 (day 0 = day of estrus), 9 or 10, 21 or 22 and 27 or 28 following breeding in 200 lactating dairy cows. Tentative diagnosis of pregnancy was made based on concentrations of progesterone in milk on days 21 and 22 alone and on days 21 or 22 and 27 or 28. In addition all cows were palpated per rectum on days 21 or 22 postbreeding and a tentative pregnancy diagnosis was made. Pregnancy was confirmed by examination of the genital tract per rectum between 35 and 50 days after breeding. Values of 4 ng/ml or greater and/or the presence of a mature corpus luteum were considered positive signs of pregnancy. Progesterone in milk ranged from 0.1 to 18 ng/ml. On days 0 or 1, 9 or 10, 21 or 22 and 27 or 28 concentrations of progesterone in milk averaged 1.5 +/- 0.3, 11.1 +/- 0.5, 12.0 +/- 0.4 12.5 +/- 0.5 ng/ml for pregnant cows. Corresponding samples from nonpregnant cows averaged 1.2 +/- 0.2, 10.3 +/- 0.4, 3.0 +/- 0.4, 6.8 +/- 0.6 ng/ml, respectively. Ninety-six and 104 cows were classified as pregnant and nonpregnant on days 21 or 22 as compared to 78 and 118 cows diagnosed as pregnant and nonpregnant on days 21 or 22 and 27 or 28 combined. Pregnancy detection by progesterone in milk on days 21 or 22 with pregnancy determined via rectal palpation 35 to 50 days postbreeding was 77 and 100% accurate for positive and negative diagnosis, respectively. The percent agreement using progesterone in milk on days 21 or 22 and 27 or 28 combined was 95 and 100%, respectively, for positive and negative diagnosis. Diagnosis based on rectal palpation 21 or 22 days postbreeding was 63 92 (69%) and 76 88 (87%) for pregnant and nonpregnant cows, respectively. Ten of the 200 cows had progesterone concentratins in milk of > 4 ng/ml at the time of breeding. Six of these cows were pregnant from a previous insemination. The other four cows were nonpregnant and were inseminated during the luteal phase of the cycle. In conclusion, measurement of progesterone in milk is a useful tool in early detection of pregnant and nonpregnant cows and may be useful in detecting reproductive problems in a dairy herd. It will probably be most useful when used in combination with later pregnancy diagnosis per rectum .

Induction of abortion in feedlot heifers with cloprostenol (ICI 80, 996).

PIP: The efficacy of 2 dose levels of cloprostenol (ICI 80,996), a synthetic analog of prostaglandins F2alpha, in inducing abortion in 2 groups of pregnant feedlot heifers was evaluated. The results indicate that cloprostenol is a safe and effective abortifacient agent at a dose of 250 mcg up to Day 120 of pregnancy. Other trials have shown a dose of 325 mcg to be as effective as 500 mcg.^ieng