Estrous detection intensity and accuracy and optimal timing of insemination with automated activity monitors for dairy cows.

The objectives of this observational study were to assess the ability of automated activity monitoring (AAM) to detect estrus for first insemination, the accuracy of detection, and the optimum interval from the estrus alert from the AAM system to insemination. Four commercial farms using 1 of 2 commercial AAM systems were studied over 1 yr. Cows were inseminated between 55 and 80 d in milk (DIM) based on AAM only, then by a combination of AAM and timed artificial insemination (AI). Blood progesterone was measured in 1,014 cows at wk 5, 7, and 9 postpartum; purulent vaginal discharge (PVD) was assessed at wk 5; and lameness and BCS at wk 7. Overall, AAM detected 83% of cows in estrus by 80 DIM. Cows that had 3 serum progesterone <1 ng/mL, had PVD, or were both lame and had BCS ≤2.5 has lesser odds of being detected in estrus by 80 DIM (62, 68, and 53%, respectively). Blood samples were collected on the day of 445 AI based on AAM and 323 timed AI. The proportion of cows not in estrus (progesterone >1 ng/mL) on the day of AI was similar between AAM (4 ± 1.8%) and timed AI (3 ± 1.2%). Managers elected, based on subjective criteria, not to inseminate 17% of cows for which an AAM estrus alert was issued, of which 43% were not in estrus. Activity data were extracted from AAM software for 1,399 AI. Onset of estrus was calculated using the same or similar data processing criteria as the AAM system. Producers recorded the time of AI. The interval from onset of estrus to AI was categorized as 0 to 8, 8 to 16, or 16 to 24 h. We found no effect of AAM system on the probability of pregnancy per AI, but noted an interaction of interval with parity. For multiparous cows, the probability of pregnancy per AI was 31%, which did not differ with the interval to AI. For primiparous cows, the odds of pregnancy were greater if AI occurred 0 to 8 h (49%) than 8 to 16 (36%) or 16 to 24 h (31%) after the estrus alert from the AAM. Automated activity monitoring can detect estrus for first AI in just over the length of 1 estrous cycle for over 80% of cows, but the remainder would likely require intervention for timely insemination. For multiparous cows, performing AI based on AAM once per day would not affect pregnancy per AI, but for primiparous cows AI within 8 h of the onset of estrus may be advantageous.

Risk factors and effects of postpartum anovulation in dairy cows.

The objectives were to identify risk factors for and to quantify the effect of postpartum anovulation on reproductive performance in dairy cows. Data from 2,178 Holstein cows in 6 commercial herds enrolled in a randomized clinical trial were used. Data on periparturient disease incidence, calving history, and body condition score were collected. Cows were examined at wk 5 postpartum for reproductive tract disease; cytological endometritis was defined as ≥6% polymorphonuclear cells in endometrial cytology, and purulent vaginal discharge was defined as the presence of mucopurulent or purulent vaginal discharge. Cows were followed until 300 d in milk (DIM) for reproductive performance. Serum nonesterified fatty acids (NEFA) concentration was measured once during the week before expected calving. Serum ß-hydroxybutyrate, NEFA, and haptoglobin were measured at wk 1, 2, and 3 postpartum. Serum progesterone (P4) was measured at wk 3, 5, 7, and 9 postpartum. The end of the postpartum anovulation period was defined as the first sampling time at which P4 was >1 ng/mL. Statistical analyses were performed using logistic regression models and Cox proportional hazard models. The prevalence of anovulation was 72, 44, 26, and 17% at wk 3, 5, 7, and 9, respectively. Cows were classified according to their ovulatory status as having luteal function at 21 DIM (Cyc21), as having low P4 at 21 DIM but having luteal function at least once at 35 or 49 or 63 DIM (Cyc63), or being anovulatory at 63 DIM (Anov63; no samples with P4 >1 ng/mL). Factors associated with early ovulation (Cyc21) included season, parity, decreased haptoglobinemia, and decreased serum NEFA concentration before and after parturition. Risk factors for prolonged anovulation (Anov63) included cytological endometritis, increased haptoglobinemia, and greater serum NEFA concentrations before and after parturition. Cows classified as Anov63 had an increased median time to first breeding compared with Cyc63 (74.1 vs. 73.2 d). The effect of prolonged postpartum anovulation on median time to pregnancy was conditional on parity group; a detrimental effect was present in cows of parity ≥3 (129 d for Cyc21, 151 d for Cyc63, and 180 d for Anov63), but no effect was observed in cows of parity ≤2. Overall, these findings suggest that postpartum anovulation was associated with indicators of energy balance and uterine inflammation, and with detrimental effects on reproductive performance.

Reproductive performance with an automated activity monitoring system versus a synchronized breeding program.

The objective was to compare reproductive performance with management programs based on an automated activity monitoring (AAM) system or a synchronized breeding program under field conditions. In total, 1,429 Holstein cows from 3 commercial herds in Ontario, Canada, were enrolled over 1 yr in a randomized controlled trial. At each farm, primiparous and multiparous animals were housed in separate pens. At the pen level, cows were assigned to reproductive management primarily using an AAM system based on monitoring activity levels (Heatime, SCR Engineers Ltd., Netanya, Israel) or a timed artificial insemination (TAI) program. A crossover occurred after 6 mo of the trial to avoid confounding treatment with parity. Insemination based on additional detection of estrus by visual observation was practiced in all pens. At the individual cow level, time to pregnancy throughout the study (n=1,985 cow-6 mo periods), time to first service, and time to second service were analyzed with a Cox proportional hazards models accounting for herd, and did not differ overall between the AAM and TAI treatment groups. However, we observed an interaction between herd and breeding program, such that association of AAM- or TAI-based program with these outcomes differed between farms. Time to pregnancy was not different in herd A [median=151 and 136 d; hazard ratio (HR) = 0.93] and herd C (median=99 and 124, HR = 1.24), whereas herd B had a median time to pregnancy of 119 d and 146 d (HR = 1.3) in the AAM and TAI groups, respectively. Under conditions in which 19 to 32% of artificial inseminations in both groups were based on visually detected estrus, herd pregnancy rate and cow-level time to pregnancy did not differ overall between TAI- and AAM-based programs, but the effect of reproductive management approach depended on herd. Considering 924 cow-6 mo periods with artificial inseminations only by the assigned program, we also found an interaction between herd and breeding program. Stratified analysis showed no difference in time to pregnancy in herd A (HR = 1.3), whereas in herds B (HR = 1.7) and C (HR = 2.8), cows in the AAM treatment group became pregnant sooner compared with those in the TAI group. Factors that influence the variability in relative performance of these management systems between herds require further investigation. Our study used one commercial activity monitoring system and the results cannot necessarily be generalized to other systems.

Randomized clinical trial of antibiotic and prostaglandin treatments for uterine health and reproductive performance in dairy cows.

The objectives of this study were to assess the efficacy of antibiotic treatment for preventing postpartum uterine disease among cows at high risk of uterine disease, and to assess the efficacy of PGF(2α) for treating cytological endometritis (CYTO) and purulent vaginal discharge (PVD). A total of 2,178 Holstein cows in 6 herds were enrolled in a randomized clinical trial. Within 24h after parturition, cows were classified at being at high risk of uterine disease (HRUD; n=1,017) if they had twins, dystocia, or retained placenta. All remaining cows were classified as being at low risk of uterine disease (LRUD; n=1,161). Cows in the HRUD group were randomly allocated in a factorial design to receive ceftiofur crystalline free acid (CCFA) at 24h after parturition or be untreated, and to receive dinoprost (PGF(2α)) at 35 and 49 (±3) days in milk (DIM) or to be untreated. Cows in LRUD were randomly allocated to receive PGF(2α) at 35 and 49 (±3) DIM or to be untreated. Serum progesterone was measured at 21, 35, 49, and 63 (±3) DIM. Cows were examined at 35 (±3; exam 1) and 56 (±3; exam 2) DIM for CYTO (by cytobrush device; ≥6% polymorphonuclear cells in endometrial cytology) and for PVD (by Metricheck device; mucopurulent or purulent vaginal discharge). Statistical analyses were performed using multivariable logistic regression models accounting for herd clustering. Treatment with CCFA in HRUD cows was not associated with the probability of metritis overall, but interactions occurred such that CCFA decreased the incidence of metritis among HRUD cows that did not have retained placenta and among cows of parity ≥2. Treatment with CCFA in HRUD cows decreased the probability of PVD at exam 1. Treatment with PGF(2α) did not affect the probability of cure of CYTO or PVD irrespective of progesterone concentration at the time of treatment. Among cows affected by CYTO or PVD at exam 1, 66 and 63%, respectively, had spontaneously cured at exam 2. Cows persistently affected at exam 2 had an increased time to pregnancy and were more likely to have both CYTO and PVD at exam 1. Administration of PGF(2α) at both 5 and 7 wk postpartum did not mitigate the effects of CYTO or PVD on reproductive performance. Clinical approaches to treatment of chronic postpartum reproductive tract infection and inflammation should be reassessed.

Effects of postpartum uterine diseases on milk production and culling in dairy cows.

The objective was to quantify the effect of postpartum uterine diseases on milk production and culling. Data from 2,178 Holstein cows in 6 herds enrolled in a randomized clinical trial were used. Milk production data from the first 4 Dairy Herd Improvement Association (DHIA) test-days and culling data from farm records were collected. Retained placenta (RP; ≥24 h after parturition) and metritis [≤20 d in milk (DIM)] were diagnosed by farm managers using standardized definitions. Farms were visited weekly and cows were examined at 35 and 56 (±3) DIM using endometrial cytology (cytobrush device), vaginal discharge scoring (Metricheck device), and measurement of cervical diameter by transrectal palpation. Diagnostic criteria for cytological endometritis (CYTO) and purulent vaginal discharge (PVD) were established based on a detrimental effect on subsequent reproduction. Statistical analyses were performed using linear mixed models, logistic regression models, and Cox proportional hazard models, accounting for the effects of experimental treatments and herd clustering. Milk production and culling were the outcomes. Primiparous and multiparous cows were modeled separately for milk production. Milk production of primiparous cows was unaffected by uterine diseases. The effect of metritis on milk production was variable over time in multiparous cows: it decreased production per cow by 3.7 kg at the first DHIA test, but was not different at later tests. Retained placenta decreased milk production by 2.6 kg/d in multiparous cows through the first 4 DHIA tests. The projected effects of metritis and RP in multiparous cows were reductions of 259 kg and 753 kg over 305 DIM, respectively; these effects were additive. Neither CYTO nor PVD affected milk production. Culling risks at 30 and 63 DIM were unaffected by RP and metritis. Culling hazard up to 300 DIM was unaffected by RP, metritis, CYTO, or PVD, whether or not pregnancy status, milk production, and displaced abomasum were accounted for. Uterine disease decreased pregnancy rate, which was a substantial risk factor for culling; however, if affected cows became pregnant they were not at greater risk of culling.

Risk factors for postpartum uterine diseases in dairy cows.

The objective of this observational study was to investigate the risk factors for metritis, purulent vaginal discharge, and cytological endometritis. The hypothesis was that purulent vaginal discharge and cytological endometritis would have different risk factors because they represent distinct manifestations of uterine disease. Data generated from 1,363 Holstein cows (3 herds) enrolled in a randomized clinical trial were used. Calving history, periparturient disease incidence, and body condition score at calving and at 63 d in milk (DIM) were recorded. Serum nonesterified fatty acid concentration was measured once during the week before expected calving. Serum nonesterified fatty acid, ß-hydroxybutyric acid, and haptoglobin (Hapto) concentrations were measured at 4 ± 3, 11 ± 3, and 18 ± 3 DIM. Serum progesterone concentration was measured at 21 ± 3, 35 ± 3, 49 ± 3, and 63 ± 3 DIM. Metritis was diagnosed by farm managers within the first 20 DIM using a standardized definition. Cows were examined at 35 ± 3 DIM by a veterinarian for purulent vaginal discharge (mucopurulent or worse vaginal discharge; Metricheck device) and cytological endometritis (≥ 6% polymorphonuclear cells on endometrial cytology; cytobrush device). Statistical analyses were performed using multivariable logistic regression models for each disease, accounting for the random effect of herd. Risk factors for metritis included increased nonesterified fatty acid prepartum (≥ 0.6 mmol/L), dystocia, retained placenta, and increased Hapto in the first week postpartum (≥ 0.8 g/L). Risk factors for purulent vaginal discharge included twinning, dystocia, metritis, and increased Hapto (≥ 0.8 g/L) in the first week postpartum. Risk factors for cytological endometritis included low body condition score at parturition (≤ 2.75), hyperketonemia (≥ 1,100 µmol/L), and increased Hapto (≥ 0.8 g/L) in the first week postpartum. These results support the hypothesis that some of the risk factors for purulent vaginal discharge and cytological endometritis are different, which supports that they are distinct manifestations of uterine disease.

Definitions and diagnosis of postpartum endometritis in dairy cows.

The objectives of this observational study were to determine and compare diagnostic criteria for postpartum endometritis in dairy cows. Data generated from 1,044 Holstein cows (6 herds) enrolled in a randomized clinical trial were used. Cows were examined for endometritis at 35±3 d (exam 1) and 56±3 d (exam 2) after parturition, using endometrial cytology (cytobrush technique), vaginal discharge scoring (Metricheck device; Simcrotech, Hamilton, New Zealand), and cervical diameter measurement (transrectal palpation). Reproductive data were recorded until 200 d after parturition. Diagnostic criteria for cytological and clinical endometritis were determined based on detrimental effect on subsequent reproductive performance, using logistic regression and Cox proportional hazard models accounting for the effect of herd clustering. Comparison of diagnostic criteria was performed using endometrial cytology as reference test or by quantifying the agreement between diagnostic approaches. At exam 1, diagnostic criteria were ≥6% polymorphonuclear cells and mucopurulent or worse (purulent or foul) vaginal discharge for cytological and clinical endometritis, respectively. At exam 2, diagnostic criteria were ≥4% polymorphonuclear cells and mucopurulent or worse vaginal discharge for cytological and clinical endometritis, respectively. Cows were classified as having cytological endometritis only, clinical endometritis only, or both cytological and clinical endometritis. Prevalence at exam 1 was 13.5, 9.4, and 5.8% for cytological endometritis only, clinical endometritis only, and both cytological and clinical endometritis, respectively. The detrimental effects of cytological and clinical endometritis on reproductive performance were additive. Among cows with clinical endometritis, only 38 and 36% had cytological endometritis at exam 1 and exam 2, respectively. Combination of diagnostic criteria improved neither the accuracy for predicting cytological endometritis nor the agreement between cytological and clinical endometritis. Overall, these results suggested that cytological and clinical endometritis may represent different manifestations of reproductive tract disease. They also suggested that use of the terminology clinical endometritis may not be accurate and that purulent vaginal discharge may be more descriptive.

The effect of subclinical ketosis in early lactation on reproductive performance of postpartum dairy cows.

Data generated from 796 Holstein cows enrolled in a clinical trial to investigate the health effect of a monensin controlled release capsule were analyzed to investigate the association between circulating serum beta-hydroxybutyrate (BHBA) concentration in the peri-parturient period and subsequent reproductive performance. Overall, accounting for both repeated measures within cow and clustering at the herd level, non-pregnant cows after first insemination tended to have increased circulating BHBA concentrations from 3 wk before calving to 9 wk after calving relative to pregnant cows. Including the interaction between the week of sample collection and pregnancy outcome, non-pregnant cows had higher circulating BHBA concentrations in the second week after calving than cows diagnosed pregnant after first artificial insemination. Within individual weeks, cows with circulating BHBA concentrations > or =1,000 micromol/L in the first week postpartum were less likely to be diagnosed pregnant after first insemination. In the second week postpartum, the cows with circulating BHBA concentrations > or =1,400 micromol/L were significantly less likely to be pregnant after first artificial insemination. A dose response relationship was found when a comparison of the probability of pregnancy after first insemination and duration of elevated circulating ketone bodies was investigated. The probability of pregnancy was reduced by 20% in cows diagnosed subclinically ketotic in either the first or second week postpartum. Nevertheless, cows above the subclinical ketosis threshold in both the first and second week postpartum were 50% less likely to be pregnant after first insemination. Similarly, the median time to pregnancy increased in cows experiencing elevated BHBA concentrations in either (124 d) or both (130 d) the first and second week postpartum relative to cows never experiencing elevated BHBA concentrations (108 d). To further investigate this, the effect of elevated circulating BHBA was permitted to vary with time. The effect decreased with time, such that the daily probability of pregnancy increased similar to nonsubclinically ketotic cows by approximately 160 d in milk. From this analysis, both the relative circulating concentration of BHBA and the duration of elevated circulating BHBA were negatively associated with the probability of pregnancy at first service.

Prevalence and risk factors for postpartum anovulatory condition in dairy cows.

The objectives of this research were to determine the prevalence of the anovulatory condition within a temperate region of North America and identify cow-level and herd-level risk factors for this condition. A total of 1,341 cows from 18 herds were classified as cycling or anovular based on skim milk progesterone concentration determined at 46 and 60 +/- 7 d in milk. Calving history, periparturient disease incidence, body condition score, milk ketone concentration in the first 2 wk of lactation, and first 305-d mature-equivalent milk projections were recorded. Reproductive and culling information was retrieved monthly from the Dairy Herd Improvement Association. The cow-level prevalence of anovulation was 19.5%, with a herd-specific range from 5 to 45%. Accounting for the effect of clustering at the herd level, cows experiencing a difficult calving, cows with twin calvings, displaced abomasum, and cows with subclinical ketosis in the first week after calving were at greater risk for diagnosis of anovulation. Anovular cows within herds using ovulation synchronization programs were inseminated at the same time postpartum with a 6-percentage point reduction in the probability of pregnancy relative to cycling herdmates (29.7 vs. 35.9%, respectively), whereas anovular cows in herds breeding based on observed estrus were inseminated 8 d later and suffered a 10-percentage point reduction in the probability of pregnancy at first insemination (20.3 vs. 30.5). Time to pregnancy was delayed in anovular cows by 30 d (156 vs. 126 d). Using survival analysis, the impact of anovulation decreased with time. The daily probability of pregnancy (hazard ratio) was similar to cycling cows by 165 d in milk. The results underline the important associations of peripartum health with reproductive function and performance.

Synchronization of estrus and pregnancy risk in anestrous dairy cows after treatment with a progesterone-releasing intravaginal device.

Lactating Holstein cows (located in 4 dairy herds) that had failed to display estrus as defined by increased pedometer activity by 63 +/- 3 d in milk, were enrolled to investigate the effect of a progesterone-releasing intravaginal device (PRID, n = 268) relative to a placebo intravaginal device (PID, control, n = 266) on days from device removal to artificial insemination (AI), the probability of pregnancy at first AI, and days from device removal to pregnancy. Cows were assigned randomly to receive a PRID or PID for 7 d and an injection of PGF2alpha at device removal. Upon device removal, a vaginitis score was assigned and AI occurred at observed estrus. Cows failing to display estrus within 14 d of device removal were subjected to a subsequent reproductive exam and were treated with PGF2alpha. Two percent of PRID-treated cows and 11% of control cows displayed estrus during the 7-d exposure period. Among the remaining cows, 93% of the devices were present at the scheduled removal. Cows treated with the PRID were 60% less likely to have purulent debris on the device than control cows. Vaginal reaction, however, was not associated with any of the reproductive outcomes. Investigation of the reproductive outcomes revealed a treatment x parity interaction. Progesterone-treated primiparous cows were inseminated 17 d earlier, with no significant change in the probability of pregnancy at first AI (30.3 vs. 42.0%), and no difference in median time from device removal to pregnancy (52 vs. 53 d) relative to control primiparous cows. Conversely, PRID-treated multiparous cows were inseminated 8 d earlier, with no change in probability of pregnancy at first AI (24.6 vs. 18.8%); however, median time from device removal to pregnancy was reduced by 20 d (67 vs. 87 d). These results support the efficacy of a PRID to induce estrus in previously anestrous cows. The reason, however, for the variable response between primiparous and multiparous cows was not clear.

The effect of a progesterone releasing intravaginal device (PRID) on pregnancy risk to fixed-time insemination following diagnosis of non-pregnancy in dairy cows.

The objective was to compare the probability of pregnancy after fixed-time insemination in cows diagnosed as non-pregnant and re-inseminated following the Ovsynch protocol, with or without exogenous progesterone. Cows (n=415) used in this study originated from 25 farms. Upon diagnosis of non-pregnancy between 30 and 60 days after AI, cows were randomly assigned to receive either a progesterone releasing intravaginal device (PRID; n=208) or a placebo intravaginal device (PID; n=207). All cows received GnRH at enrollment (Day 0), PGF(2alpha) concurrent with intravaginal device removal 7 days later, GnRH on Day 9 and fixed-time insemination 16h later (Day 10). Cows observed in estrus prior to Day 7, had the device removed and were inseminated. Ovaries were examined by transrectal palpation at the time of enrollment and the prominent structures were assessed and recorded. Body condition score, lameness status, interval from previous insemination, and times bred at enrollment were recorded. At intravaginal device removal, the occurrence and intensity of vaginitis was determined according to the amount of debris on the device. Overall, the intravaginal device retention rate was 91%. A total of 5.2% of PID-treated cows and 2.9% of PRID-treated cows were detected in estrus within the 7 days treatment period. Pregnancy status was diagnosed between 30 and 56 days after insemination and all cows were followed for a minimum of 150 days after enrollment. Approximately 28% of cows had evidence of mild vaginitis in response to the intravaginal device, whereas 6% of cows had copious debris associated with the intravaginal device at removal. The probability of pregnancy after fixed-time insemination was 43.8% versus 34.9% in PRID-treated versus PID-treated animals. Exogenous progesterone provided through an intravaginal device to non-pregnant cows that had not displayed estrus improved the probability of pregnancy after fixed-time AI.

Effect of presynchronization using prostaglandin F2alpha and a milk-ejection test on pregnancy rate after the timed artificial insemination protocol, Ovsynch.

The objective of this research was to determine if PGF2alpha-induced milk letdown (ML) is an accurate indicator of luteolysis, allowing cows to be synchronized to begin the Ovsynch protocol (GnRH-7d-PGF2alpha-2d-GnRH-24h-AI) at the most beneficial time of the estrous cycle (days 5-9), and determine if this would improve pregnancy rate (PR). Lactating Holstein cows between 55 and 70 days in milk were used to evaluate the ML test and PR after the Ovsynch protocol, when initiated on the basis of the test result (PROSYNCH). PROSYNCH cows (n = 60) had one teat cannulated to test for ML and were treated with 500 microg cloprostenol, PGF2alpha analogue (PG). Cows with ML were started on Ovsynch 10 days later, and those without started 3 days later. Cows in the control group (OVSYNCH, n = 64) were injected with physiological saline and observed for ML. This group was started on Ovsynch 10 days after saline treatment. Milk samples were collected thrice weekly to determine progesterone concentrations. ML indicated luteolysis with a sensitivity of 98% and a specificity of 60%. The positive and negative predictive values were 83 and 92%, respectively. Pregnancy rates were 48% for PROSYNCH and 52% for OVSYNCH (P = 0.72). When data from both groups were combined, PR was greater in cows that started the Ovsynch protocol in stage 2 of the estrous cycle (days 5-9, 67%) than all other stages (stage 1: days 1-4, 35%; stage 3: days 10-16, 45%; stage 4: days 17-21, 42%; P < 0.01). The proportion of animals with ovulation after GnRH#1, luteolysis after PGF2alpha, and ovulation after GnRH#2 were all greater in the PROSYNCH group (77% versus 55%, P < 0.02; 83% versus 66%, P < 0.03; 97% versus 84%, P < 0.03, respectively). Therefore, the ML test indicated luteolysis with sufficient precision to time the initiation of the Ovsynch protocol between days 5 and 9 of the cycle, however, this did not alter PR compared to starting the protocol randomly throughout the cycle. Initiating the Ovsynch protocol between days 5 and 9 of the cycle increased PR, and improved the efficacy of each injection.

The effect of a single administration of cephapirin or cloprostenol on the reproductive performance of dairy cows with subclinical endometritis.

This study examined the effect of a single administration of cephapirin iu or cloprostenol im on the reproductive performance of dairy cows with subclinical endometritis. Cows (n = 228) at 20-33 days in milk (DIM) from two commercial dairy farms, determined to be normal for clinical endometritis (based on absence of abnormal uterine discharge on vaginoscopic examination) were enrolled. At enrollment, a thorough reproductive examination was performed, including rectal palpation, ultrasonography (US) and endometrial cytology (EC). The case definition for subclinical endometritis was the presence of >18% neutrophils on EC examination or fluid in uterus (FIU) on US examination. All cows were randomly assigned to receive one of three treatments: 500 mg benzathine cephapirin iu, 500 microg cloprostenol im, or control (no treatment). Reproductive performance was monitored for a minimum of 8 months after treatment. Cows with subclinical endometritis treated with cephapirin or cloprostenol had a significantly increased relative pregnancy rate compared to control [hazard ratios 1.89 (P = 0.01) and 1.70 (P = 0.05), respectively]. In conclusion, a single treatment with cephapirin or cloprostenol at 20-33 DIM significantly improved the reproductive performance of cows with subclinical endometritis.

Identification and measurement of 4-oestren-3,17-dione (19-norandrostenedione) in porcine ovarian follicular fluid using high performance liquid chromatography and capillary gas chromatography-mass spectrometry.

4-Oestren-3,17-dione (19-norandrostenedione) has been identified as a major steroid in porcine ovarian follicular fluid for the first time. This steroid was isolated by C18 reverse-phase high performance liquid chromatography (HPLC) and its structure was established unambiguously by capillary gas chromatography-mass spectrometry. The mean concentration in pooled fluid obtained from prepubertal gilts determined by HPLC and capillary gas chromatography was 1.71 mumol/l. The leve of this steroid in fluid obtained from large preovulatory follicles of sows exceeded 21.0 mumol/l on days 19 and 20 of the oestrous cycle. The high levels of this steroid within the follicle during the follicular phase might imply a possible biological role in follicular development and oocyte maturation.

Feedback control of follicle-stimulating hormone in pre-and postpubertal rams as revealed by hemicastration.

The levels of FSH, LH and testosterone in the plasma were measured in cross-bred male lambs which were bilaterally castrated, hemicastrated or left entire at 1 week of age. Removal of one testis caused the level of FSH in the circulation to increase to a value midway between the levels found in entire and castrated lambs up to 12 weeks of age. The concentrations of LH and testosterone in the plasma were similar in the control and hemicastrated lambs. The concentration of FSH in the plasma of the hemicastrated lambs fell at 12--14 weeks of age, the expected time of puberty, to the level found in control animals of the same age. Although the possibility of increased release of LH cannot be excluded, the increase in the secretion of FSH is believed to account for the compensatory hypertrophy of the remaining testis observed in the hemicastrated lambs. Removal of one testis from mature Soay rams in sping (May) caused a small selective increase in the concentration of RSH in the plasma, compared with entire animals. This difference was maintained until July when there was a marked increase in the levels of FSH and LH in the hemicastrated rams such that an exaggeration of the normal seasonal changes in these hormones was observed. Compensatory hypertrophy of the remaining testis was observed in the hemicastrated animals.

Development and application of a heterologous radioimmunoassay for ovine follicle-stimulating hormone.

A highly specific and sensitive heterologous double antibody radioimmunoassay for ovine follicle-stimulating hormone (oFSH) is described in detail. The assay using a rabbit antiserum to human FSH and either 125I-labelled rat FSH or 125I-labelled oFSH as tracer is specific for FSH. A maximum cross-reaction (B/Bo = 50%) of 0-1% was observed with other ovine, rat or human pituitary hormones or human chorionic gonadotrophin. Serum levels of oFSH in samples collected daily throughout the oestrous cycle showed large individual variations. In five out of nine animals a peak of FSH was observed on the day of oestrus.

Production of anti-idiotypic antibodies resembling bovine somatotropin by active immunization of lactating cows.

Anti-idiotypic antibodies produced in lactating cows by immunization with rabbit antibodies raised against bovine somatotropin (bST) were evaluated for bST-like immunoactive and biological activities. Twenty New Zealand White rabbits were immunized against bST. Serum was purified using protein A-Sepharose CL-4B and bST-Sepharose 4B affinity chromatography to yield specific anti-bST immunoglobulin G (IgG). Twenty-four lactating cows were allocated to a randomized complete block design and were immunized with either: (1) rabbit anti-bST (n = 12) or (2) non-specific rabbit IgG (n = 12, control). Cows were immunized starting at day 68 of lactation with 800 micrograms antigen emulsified with Freund's complete adjuvant and 1 mg Quil A administered by i.m. injections. Repeated immunizations of 800 micrograms antigen in Freund's incomplete adjuvant and 1 mg Quil A followed after 3 weeks and then every 5 weeks throughout lactation. Serum samples were collected twice weekly and were analysed for anti-rabbit IgG titre and immunoactive bST concentration by radioimmunoassay. All cows developed antibodies against rabbit IgG by the second and third immunizations. With rising titres, immunoactive bST concentrations increased in cows treated with anti-bST following each of the six repeated immunizations to 4.7 +/- 3.3, 10.0 +/- 4.2, 12.0 +/- 4.8, 17.3 +/- 6.7, 24.0 +/- 10.0 and 36.3 +/- 20.4 ng/ml (mean +/- S.E.M.) compared with controls (0.81 +/- 0.09 ng/ml, overall mean +/- S.E.M.). To assess the biological activity of these bST anti-idiotypic antibodies, milk yield and serum insulin-like growth factor-I (IGF-I) concentrations were analysed in all cows and a subset of six cows per treatment respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Follicle-stimulating hormone release in hemicastrated prepubertal rams and its relationship to testicular development.

Hemicastration of rams at 1 week of age resulted in compensatory growth of the remaining testis. This was associated with an increase in the concentration of FSH in peripheral plasma which was maintained until the rams were approximately 10 weeks old. Plasma concentrations of LH were similar in both entire and hemicastrated lambs during this period. Pulsatile release of LH was observed in all rams from approximately 6 weeks of age onwards. The frequency of these pulses increased and the size of each pulse declined as the animals grew older. At 16 weeks pulsatile release was almost undetectable and the basal levels of LH had increased. The increased concentration of FSH in plasma was related to the size of the remaining testis but not to its development. The return of the plasma concentration of FSH to values similar to those found in entire rams preceded the appearance of a lumen or of any primary spermatocytes in the seminiferous tubules. Restricting the development of the remaining testis in hemicastrated rams, by trapping it in the inguinal region, did not alter the FSH response to hemicastration. The administration of gonadotrophin releasing hormone (10 microgram) at 10, 13 and 18 weeks of age provoked release of similar quantities of LH in both entire and hemicastrated rams. There was also a substantial release of FSH at 10 weeks of age but this response declined with age and by 18 weeks there was little FSH released in any of the animals. This loss of response occurred earlier in the hemicastrated rams. The data suggest that in prepubertal rams the release of FSH but not of LH is restricted by a substance produced by the developing Sertoli cells.

The effect of atropine on cadmium- and nickel-induced constriction of vascular smooth muscle of the dogfish shark ventral aorta.

We investigated the effect of blockade of muscarinic, cholinergic receptors by atropine on the Cd2(+)- and Ni2(+)-induced vasoconstriction of rings of endothelium-free, vascular smooth muscle from the ventral aorta of the dogfish shark, Squalus acanthias. Atropine reduced the Cd2(+)-induced vasoconstriction by approximately 50%, but did not alter the Ni2(+)-induced vasoconstriction, suggesting that the vasoactivity of these two metals may be, at least partially, via different pathways. In addition, this is the first demonstration that one component of Cd2+ vaso-toxicity may be via stimulation of muscarinic receptors.

Complete brachial plexus palsy after total shoulder arthroplasty done with interscalene block anesthesia.

BACKGROUND AND OBJECTIVES: This report illustrates that brachial plexus palsy can result from either interscalene block or total shoulder arthroplasty. It is often impossible to determine which procedure caused the deficit; therefore, we believe the focus should be placed on treatment of the neurologic deficit. This report provides a suggested algorithm for diagnosis and treatment of postprocedure brachial plexus palsy. METHODS: Interscalene block was used as the operative anesthetic for our patient's total shoulder arthroplasty. Complete brachial plexus palsy was diagnosed postoperatively. RESULTS: The patient's postoperative treatment and recovery are described. CONCLUSIONS: Proper diagnosis and treatment of postprocedure brachial plexus palsy may improve recovery of function. Several precautions may reduce the likelihood of brachial plexus palsy following interscalene block for total shoulder arthroplasty.