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The objectives of this study were as follows: 1) to evaluate the association among abnormal calving, parity, and season on the incidence of puerperal metritis (PM) and clinical endometritis (CE) during d 3 to 13 and 20 to 30 postpartum, respectively; 2) to describe the rectal temperature (RT) of cows with PM before diagnosis; and 3) to document associations among PM, CE, and reproductive performance in lactating dairy cows. This study followed a prospective observational study design. Cows were classified as having an abnormal calving status (AC), i.e., cows calving with dystocia, twins, retained fetal membranes, or some combination of these conditions, and having a normal calving status (NC). Daily RT was recorded from d 3 to 13 postpartum for all cows, and health examinations were performed on cows that appeared not well. A total of 450 calvings were evaluated. Cows with an AC had greater odds of PM than cows with NC [adjusted odds ratio (AOR) = 4.8; 95% confidence interval (CI) = 2.9 to 8.0). A season by parity interaction showed that primiparous cows that calved during the warm season had lower AOR of PM than during the cool season (0.24; 95% CI = 0.09 to 0.62), whereas multiparous cows did not have seasonal effects on PM (1.43; 95% CI = 0.65 to 3.18). Cows with AC have greater AOR for CE than cows with NC (2.8; 95% CI = 1.7 to 4.9), and greater AOR of CE were detected in cows diagnosed with PM than in cows without PM (2.2; 95% CI = 1.1 to 3.9). Rectal temperature in cows with PM increased significantly 24 h before diagnosis of PM, reaching 39.2 ± 0.05°C on the day of diagnosis. In cows with PM and fever at diagnosis, the RT began to increase from 72 to 48 h before the diagnosis of PM and continued to increase to 39.7 ± 0.09°C on d 0 (day of diagnosis). Nonetheless, cows with PM without fever at diagnosis had no daily increases in RT before diagnosis of PM. Still, the RT on d 0 was different from cows without PM. Cows without PM had a stable RT (38.6 ± 0.01°C). There were no detected differences in first-service conception risk or cumulative pregnancy risk by 150 d postpartum between cows with or without PM. Still, a season effect on first-service conception AOR (warm vs. cool = 0.98; 95% CI = 0.18 to 0.72) and accumulated pregnancy AOR by 150 d postpartum was detected (warm vs. cool = 0.18; 95% CI = 0.10 to 0.33). [ABSTRACT FROM AUTHOR]

The objective of this study was to compare reproductive performance of lactating dairy cows bred by natural service (NS) or timed AI (TAI). One thousand fifty-five cows were blocked by parity and enrolled to receive either NS or TAI. Cows in both groups were presynchronized with 2 injections of PGF2α given at 42 and 56 d postpartum. Fourteen days after the last PGF2α injection, cows in the TAI group were enrolled in an Ovsynch protocol (d 0 GnRH; 7 d later, PGF2α; 56 h after PGF2α injection, second dose of GnRH; and 16 h after second GnRH cows were TAI). Cows in the TAI group were resynchronized with an intravaginal insert containing progesterone inserted 18 d after TAI and removed 7 d later when GnRH was given. Cows were examined by ultrasonography on d 32 after TAI; nonpregnant cows received PGF2α and GnRH 56 h later followed by TAI 16 h after the GnRH injection. Nonpregnant cows in TAI group were reinseminated up to 5 times using the same scheme. Cows in the NS group were exposed to bulls 14 d after the second PGF2α injection, and ultrasonography was performed 42 d after exposure to bulls to determine pregnancy status. Nonpregnant cows in the NS group were reexamined by transrectal palpation combined with ultrasound every 28 d until diagnosed pregnant or 223 d postpartum, whichever occurred first. Cows diagnosed pregnant in TAI or NS were reconfirmed 28 d later to determine pregnancy loss. All bulls underwent an evaluation of breeding soundness and were rested for 14 d after 14 d of cow exposure. Health disorders were evaluated up to 70 d postpartum, and body condition score was evaluated at d 70 postpartum. Blood was collected on d 56 and 65 postpartum and analyzed for progesterone to determine cyclicity. The proportion of pregnant cows in the first 21 d of breeding did not differ between groups. The overall 21-d cycle pregnancy rate (PR), which included a total of 8 and 5 service opportunities for NS and TAI, respectively, was not different between groups (25.7 and 25.0% for NS and TAI, respectively). The daily rate of pregnancy was 15% greater for NS than TAI because cows in NS had a greater PR, which resulted in fewer median days open (111 vs. 116 d). Proportion of pregnant cows at 223 d postpartum was greater in the NS than TAI group (84.2 vs. 74.8%, respectively). Cyclicity did not affect reproductive performance. Cows with body condition score ≥2.75 had greater proportion of pregnant cows in the first 21 d of breeding and daily PR in the first 223 d postpartum Primiparous cows had greater proportion of pregnant cows and daily PR than multiparous cows at 223 d postpartum. In conclusion, the greater proportion of pregnant cows in the NS group was attributed to more opportunities for breeding than in the TAI group. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the effect of the Ovsynch protocol with and without exogenous progesterone on pregnancy rate (PR) in cows in which estrous cycles were previously synchronized with 2 doses of PGF2α and that were not detected in estrus during the presynchronization period. The study was conducted in Chihuahua, Mexico (8,650 Holstein milking cows; 305-d mature equivalent milk yield = 13,790 kg). On d 47 postpartum, estrous cycles in cows were synchronized by using 2 doses of PGF2α 14 d apart. Any cow detected in estrus during this presynchronization period was inseminated. Cows not detected in estrus were selected at random and assigned to receive progesterone supplementation or to serve as controls. Controls (n = 594) were subjected to the Ovsynch protocol and cows in the progesterone supplemented treatment (n = 594) were subjected to the Ovsynch protocol plus an intravaginal insert containing 1.9 g of progesterone inserted at the time of the first GnRH injection and removed 7 d later. Progesterone-supplemented cows had a greater PR (31.2%) compared with controls (22.7%). Plasma progesterone concentrations at artificial insemination (AI) were <1 ng/mL and did not differ between treatments. At 14 d post-AI, however, more cows that received progesterone supplementation had concentrations of progesterone >1 ng/mL compared with controls. It was concluded that after a presynchronization period, cows subjected to the Ovsynch program and supplemented with exogenous progesterone had a greater PR and greater concentrations of progesterone after AI than those subjected to the Ovsynch protocol and not supplemented with progesterone. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the economic benefits of timed artificial insemination (AI) and a progesterone insert as therapeutic treatments for cows diagnosed with cystic ovarian disease (COD). A secondary objective was to illustrate the use of a stochastic dynamic simulation model to fully account for all changes in revenues and costs affected by differences in treatments. First, 4 herds of 1,000 cows each were simulated until steady state. These cows were free from COD and inseminated based on estrus only. Herds differed by probability of estrus detection (46 or 70%) and days in milk (DIM) when nonpregnant cows were culled (330 or 400 d). Second, 3 herds were created with 1,000 nonpregnant cows at 90, 170, or 250 DIM. These cows were considered diagnosed with COD at the start of the simulation (d 0); no new cases of COD developed after d 0. Cows spontaneously recovered or were treated. Treatments were either timed AI or intravaginal device containing progesterone followed by PGF2a, and then AI if estrus was detected. Effects of treatments were evaluated in 48 scenarios based on compliance of timed AI (82 or 100%), probability of estrus detection (46 or 70%), and DIM when nonpregnant cows were culled (330 or 400 d). As cows became pregnant or were replaced, the herd evolved into the associated steady-state herd. Seven scenarios resulted in less than 50% of cows conceiving before they were culled. The percentage of cows diagnosed with COD that calved again ranged from 14.0 to 74.4% and was significantly reduced when COD was diagnosed later in lactation. Treatments in all cases were more valuable than waiting for spontaneous recovery. The average values of timed AI (82 or 100% compliance) and the progesterone insert were $83.29, $86.83, and $71.89, respectively, compared with waiting for spontaneous recovery. Treatments were least beneficial at 90 DIM. The benefits of timed M (82 or 100% compliance) compared with the progesterone insert, adjusted for DIM and days to culling, were $14.98 and $21.53 when the probability of estrus detection was 46%. At 70% probability of estrus detection, the benefits were $7.81 and $8.34, respectively. Overall benefit of treatment by timed AI was $11.39 greater than by progesterone insert. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the effect of a monensin controlled-release capsule administered intraruminally at dry-off on rumen volatile fatty acids, NH3, lactate, pH, and energy blood metabolites in transition dairy cows fed Florida typical diets. In March 2003, 24 cows (10 primiparous and 14 multiparous) dried-off 50 to 70 d before expected parturition were randomly assigned to a treatment (n = 12, oral capsule of monensin) or a control group (n = 12, no capsule). Both groups received the same diet and were exposed to the same environment and management conditions. At assignment, at 21 d before expected parturition, at calving, and at 7, 14, and 21 d postpartum, blood samples were taken and body condition scores were determined. At 10 d postpartum, rumen and blood samples were obtained in the morning before the first feeding and at 2, 4, and 6 h after feeding. Serum nonesterified fatty acids (NEFA), β-hydroxybutyrate (BHBA), and glucose were measured. Rumen samples were analyzed for concentrations of acetic, propionic, butyric, L- and D-lactic acids, and NH3. Data for rumen and blood metabolites were analyzed by ANOVA, mixed models for repeated measures. Volatile fatty acids were not different between groups. Multiparous treated cows had a significant reduction in rumen NH3 at 6 h after feeding. Treatment with monensin significantly increased body condition score at calving in multiparous cows. During the postpartum period, NEFA and BHBA were noticeably lower in treated than in control primiparous cows. This difference was not observed in multiparous cows. [ABSTRACT FROM AUTHOR]

The objective was to evaluate the effect of 2 doses of PGF2α injected early postpartum on uterine involution, serum concentration of acute phase proteins at 12 d postpartum, and fertility in Holstein cows with acute puerperal metritis. Only cows diagnosed with retained fetal membranes and metritis and treated with ceftiofur hydrochloride for 5 d were used in the study. Two hundred cows were assigned randomly to be treated (n = 100) or to serve as controls (n = 100). Treatment consisted of 2 i.m. injections of PGF2α 8 h apart on d 8 postpartum. A subsample of 90 cows was selected randomly (45 treated cows; 45 controls) to evaluate uterine diameter using ultrasonography, uterine score, and serum concentrations of acute phase proteins at 12 d postpartum. The outcome variable for all cows was conception rate at first service. Postpartum, primiparous, treated cows had smaller uterine diameters and lower uterine scores than controls. Cows with a uterine diameter < 5.1 cm at 12 d postpartum were 5.5 times more likely to conceive at first service than cows with larger uterine horn diameter. Treatment significantly reduced the concentrations of serum α1-acid glycoprotein. Within primiparous cows, treatment also increased conception at first service by 17%. It was concluded that 2 doses of PGF2α 8 h apart at 8 d postpartum in primiparous cows with acute puerperal metritis decreased the diameter of uterine horns and serum concentration of α1-acid glycoprotein at 12 d postpartum and increased the conception rate at first service. [ABSTRACT FROM AUTHOR]

This study was conducted to compare efficacy of treatments with EB or GnRH and different quantities of exogenous progesterone (P 4 ) for synchronization of time of ovulation on follicular growth and pregnancy in lactating dairy cows. In Experiment 1, 40 cows were treated with EB or GnRH and 1.9 or 3.0 g of P 4 via progesterone-containing intravaginal devices (IVPD; D0), two doses of PGF 2α on D7, GnRH on D9, and TAI on D10. In Experiment 2, 1,440 cows were treated with EB or GnRH and 1 g IVPD on D0, cloprostenol, eCG and EB on D7. Cows in estrus by 48 h were AIDE, and non-estrous cows were administered GnRH and TAI 60 h after IVPD removal. Non-estrous cows were AIDE 72 h after IVPD removal. In Experiment 1, P 4 was greater on D7 for cows treated with GnRH than those treated with EB. The dominant follicle was larger for cows treated with GnRH than those treated with EB. In Experiment 2, for estrous cows, pregnancy per AI was greater in cows AI at 48 h compared to 60 h after IVPD removal for cows treated with GnRH, and greater with AI at 60 h after IVPD removal compared to 48 h in EB-treated cows. In non-estrous cows, there was no effect on pregnancy. In conclusion, treatment with GnRH compared with EB resulted in increased P 4 regardless of amount of exogenous P 4 , and there were differential proportions of estrous cows pregnant depending on time of AI after IVPD removal., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The objective was to assess the effect of biostimulation by the male presence and social organization on the interval from calving to resumption of ovarian cyclicity (ICR). Thirty Angus cows were allocated according parity into three groups (10 per group); two groups were exposed to bulls, and a third group not exposed to bulls served as a control. Dominance values (with subsequent arc-sin transformation) were calculated from daily recorded agonistic interactions and later organized into dominance order comprising three social categories as follows: dominant (D), intermediate (I), and subordinates (S). The ICR was established by determining presence of luteal tissue and a rise of blood progesterone concentration above 1 ng/mL using ultrasonography and a solid-phase, nonextraction radioimmunoassay (Coat-a-Count; Diagnostics Products Corporation, Los Angeles, CA, USA), respectively. The effect of biostimulation, dominance order, and treatment by dominance order on ICR was statistically analyzed applying ANOVA using PROC GLM of SAS (2010). The ICR was influenced by biostimulation (P < 0.002) and dominance order (P < 0.004). The ICR increased as dominance order decreased (D = 34.5 ± 6 days; I = 45.0 ± 6; S = 53.1 ± 4 days; P < 0.01). However, when comparing cows within social categories, ICR was reduced in the group exposed to bulls (D = 26.3 ± 8.2 days; I = 42.0 ± 6.4 days; S = 46.1 ± 4.1 days) compared with those not exposed to bulls (D = 43.0 ± 8.2 days; I = 48.0 ± 10.1 days; S = 60.2 ± 6.4 days) cows. In conclusion, biostimulation and social dominance influenced the ICR., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Pregnancy per artificial insemination (AI) was evaluated in dairy cows (Bos taurus) subjected to synchronization and resynchronization for timed AI (TAI). Cows (n=718) received prostaglandin F(2alpha) (PGF) on Days -38 and -24 (Days 39 and 53 postpartum), gonadotropin-releasing hormone (GnRH) on Day -10, PGF on Day -3, and GnRH and TAI on Day 0. Between Days -10 and -3, cows received a progesterone intravaginal insert (CIDR group) or no CIDR (Control group). Between Days 14 and 23, cows received a CIDR (Resynch CIDR group) or no CIDR (Resynch control group), GnRH on Day 23, with pregnancy diagnosis on Day 30. Cows in estrus (between Days 0 and 30) were re-inseminated at detected estrus (RIDE). Nonpregnant cows received PGF on Day 30 and GnRH and TAI on Day 33. Plasma progesterone was determined to be low or high on Days -24 and -10. Pregnancy rates were evaluated 30 and 55 d after AI. The CIDR insert included in the Presynch-Ovsynch protocol did not increase overall pregnancy per AI for first service (36.1% and 33.6% for CIDR; 34.1% and 28.8% for Control) but did decrease pregnancy loss (7.0% for CIDR and 15.6% for Control). The CIDR insert increased pregnancy per AI in cows with high progesterone at the time the CIDR insert was applied. Administration of a CIDR insert between Days 14 and 23 of the estrous cycle after first service did not increase overall pregnancy per AI to second service (24.7% and 22.7% for Resynch CIDR; 28.6% and 25.3% for Resynch control). For second service, RIDE cows had lower pregnancy rates in the Resynch CIDR group than in the Resynch control group. Cows with a CL (corpus luteum) at Day 30 had higher pregnancy rates in the Resynch CIDR group than those in the Resynch control group.

The objective of this study was to determine the effect of a monensin controlled-release capsule administered intraruminally at drying-off on body condition score (BCS) at calving, milk yield, fertility and concentration of energy-related blood metabolites in Holstein cows dried-off with low BCS (< or = 3.0, scale 1 to 5 with a 0.25 point of increment). Between July and August, 2001, 220 cows from parity 2 or more and dried-off 50-70 days before expected parturition, with a BCS < or = 3.0 were randomly assigned to either a treatment group (n=110; oral capsule of monensin releasing 335 mg/day for 95 days) or a control group (no capsule, n=110). At assignment, on day 21 before expected parturition, at calving, and at 7, 14, and 21 days in milk a blood sample was obtained from a random sub sample of 10 cows per group. Effects of monensin on serum NEFA, BHBA and glucose were measured. Milk yield, milk fat and protein content (%) at DHIA test days during the entire lactation, 305 ME milk production and reproductive responses were compared. Monensin significantly improved BCS at calving, increased milk yield at test days 4 and 8, decreased the percentage of milk protein, did not change the percentage of milk fat, and decreased NEFA and BHBA during the post-partum period.

The objective of this study was to evaluate the association between the level of milk production on the day of diagnosis of ovarian cysts and treatment response using the Ovsynch protocol. On the day of cyst diagnosis (Day 0), 260 lactating dairy cows with ovarian cysts were treated with gonadotropin-releasing hormone (GnRH), PGF2alpha on Day 7, GnRH on Day 9, and timed inseminated 16-20 h later (Ovsynch protocol). Pregnancy was determined (by transrectal palpation) between 42 and 49 days after insemination. On Day 0, data for milk production (kg/day), parity, days in milk (DIM), and body condition score (BCS) were recorded. Using the median value for milk production on the day of diagnosis, cows were classified as high producers (>28.5 kg) and low producers (or=0.05). Primiparous cows were more likely (adjusted odds ratio: AOR=3.63; 95% CI: 95% confidence intervals=1.28-10.30; P

The objective of this study was to evaluate the effect of biostimulation by bull exposure on the expression of estrus in postpartum Angus cows. Ninety Angus cows and their calves were allocated by parity and body frame to three pens (30/pen). From 1-week post partum, one epididectomized mature Angus bull was placed with Groups A and B (BE), whereas Group C served as a Control (NE). Data for duration of estrus (DE), total mounts received (TMR), and intensity of estrus (IE) were recorded using HeatWatch. At either the first or second postpartum estrus, there were no differences between BE and NE cows for DE, TMR and IE. However, the period after onset of estrus, cow within treatment and the interaction treatment by period exerted a significant influence on IE. Overall, the greatest IE (P<0.0001) was observed during the first two periods (6h). At the first postpartum estrus, IE tended (P<0.11) to be greater in BE than NE cows during the first 3h after onset of estrus. However, IE was greater (P<0.02) in NE cows than BE cows during 4-6h after onset of estrus. At the second postpartum estrus, IE did not differ between BE and NE cows during the first 3h after onset of estrus. However, from 4 to 9h after onset of estrus, IE was greater (P<006) in NE cows than BE cows. From the results of this study, it was concluded that DE, TMR and IE were not influenced by biostimulation. However, the manner in which mounting activities were distributed across the duration of estrus was influenced by the presence of bulls.

The objective of this study was to compare the effectiveness of the Ovsynch and controlled internal drug releasing (CIDR) protocols under commercial conditions for the treatment of cystic ovarian disease in dairy cattle. A total of 401 lactating dairy cows with ovarian cysts were alternatively allocated to two treatment groups on the day of diagnosis. Cows in the Ovsynch group were treated with GnRH on Day 0, PGF2alpha on Day 7, GnRH on Day 9, with timed insemination 16-20 h later. Cows in the CIDR group were treated with a CIDR insert on Day 0 for 7 days; on Day 7, the CIDR was removed, and cows were treated with PGF2alpha. All cows in the CIDR group were observed for estrus and cows exhibiting estrus within 7 days following removal of the CIDR and PGF2alpha administration were inseminated. The outcomes of interest for this experiment were the likelihood to be inseminated, return to cyclicity (determined by a CL on Day 21), conception and pregnancy rates. Data for these variables were analyzed using logistic regression. The percentage of cows inseminated in the Ovsynch and CIDR groups were 82 and 44%, respectively. Cows in the Ovsynch group were 5.8 times more likely to be inseminated than cows in the CIDR group. Cows with a low BCS were 0.48 times less likely to be inseminated than cows with a high BCS. The percentage of cows with a CL on Day 21 for the Ovsynch and CIDR groups was 83 and 79%, respectively (P > 0.05). Cows with a low BCS were 0.49 times less likely to have CL on Day 21 than cows with a high BCS. Conception and pregnancy rates for cows in the Ovsynch group were 18.3 and 14.4%, respectively. Conception and pregnancy rates for cows in the CIDR group were 23.1 and 9.5%, respectively. There was no significant differences between conception or pregnancy rates in cows in both groups. Primiparous cows were 2.6 times more likely to conceive than multiparous cows. In conclusion, the results of this study suggested that fertility was not different between cows with ovarian cysts treated with either the Ovsynch or the CIDR protocols in this dairy herd. In addition, primiparous cows had an increased likelihood for conception compared to multiparous cows, and cows with a low BCS were less likely to be inseminated or have a CL on Day 21, regardless of treatment.

Two experiments were performed to determine the effects of repeated administration of PGF2alpha in the immediate post partum period on the prevalence of clinical endometritis at 22 and 58 days post partum, and the probability of pregnancy at first insemination, in post partum dairy cows. In Experiment 1, 228 cows on day 7 post partum were used. Cows in Group 1 (n = 114) were treated twice with PGF2alpha (25 mg, im) 8 h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 114) served as untreated controls. Vaginoscopy and transrectal palpation of the genital tract were done on days 22 and 58 post partum. Cows in both groups were inseminated at estrus after a voluntary waiting period of 100 days. Pregnancy was determined by transrectal palpation between 45 and 50 days after insemination. Repeated administration of PGF2alpha in the immediate post partum period did not reduce the prevalence of clinical endometritis on days 22 or 58 post partum (65 versus 62% on day 22 and 28.3 versus 35.2% on day 58 in Groups 1 and 2, respectively). There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In Experiment 2, 418 cows on day 7 post partum were used. Cows in Group 1 (n = 209) were treated twice with PGF2alpha (25 mg, im) 8h apart on days 7 and 14 post partum, and only once on days 22 and 35 post partum. Cows in Group 2 (n = 209) served as untreated controls. Cows in both groups were subjected to the Presynch and Ovsynch protocols on days 49 and 75 post partum, respectively. Pregnancy was determined by transrectal ultrasonography between days 29 and 32 after timed insemination. There was no significant difference in the probability of pregnancy at first insemination between cows in both groups. In conclusion, repeated administration of PGF2alpha to cows in this herd had no effect on the prevalence of clinical endometritis at 22 and 58 days post partum, and that there was no effect on the probability of pregnancy after insemination at estrus among cows with a voluntary waiting period of > 100 days, or at timed AI at 85 days in milk when Presynch was employed.

The objective of this study was to determine the effect of a monensin controlled-release capsule on the proportion of cows with subclinical ketosis (SK). During July to August 2001, 300 cows dried-off 50-70 days before expected parturition were randomly assigned to either a treatment (n = 150, oral capsule, 335 mg/d of monesin for 95 d) or control group (no capsule, n = 150). At 14 days postpartum, a milk sample was obtained and evaluated for beta-hydroxybutyrate (BHBA) using a semi-quantitative ketone test strip. In a sub-sample of 50 cows per group a blood sample was taken and analyzed for BHBA using an ELISA kit. Milk BHBA > or = 200 micromol/L was used as the cut-off value for diagnosis of SK. The incidence of SK based on the milk test was statistically different between groups (P < or = 0.05) with a value of 26.6% for control and 14.5% for cows treated with monensin, respectively. Cows treated with monensin were 0.68 times less likely to give a positive result for milk BHBA than non-treated cows (0.53-0.80; 95% CI). Serum BHBA concentrations did not differ between groups (0.81 +/- 0.09 mmol/L versus 0.70 +/- 0.07 mmol/L for controls and treated, respectively; P > 0.05). However, for each incremental increase in serum BHBA of 0.1 mmol/L occurrence of SK increased 52% (OR = 1.52; 1.21-1.91; 95% CI).

The objective was to compare pregnancy rates to resynchronization and timed AI (TAI) protocols in lactating dairy cows that received GnRH at 23 d and were diagnosed not pregnant at 30 d after the pre-enrollment AI. Nonpregnant cows (624) at ultrasonography on day 30 (study day 0) were classified as diestrus (74.8%), metestrus (5.6%) and without a CL (19.5%). Cows in diestrus were assigned either to the GnRH group (PGF2alpha on day 0, GnRH on day 2 and TAI 16 h later, n = 238) or the estradiol cypionate (ECP) group (PGF2alpha on day 0, ECP on day 1, and TAI 36 h later, n = 229). Cows in metestrus were assigned to the Modified Heatsynch Group (GnRH on day 0, PGF(2alpha) on day 7, ECP on day 8 and TAI on day 9, n = 35). Cows without a CL (n = 122) were classified either as proestrus (10.6%), ovarian cysts (7.5%) or anestrus (1.4%), and assigned to factorial treatments (i.e., use of GnRH versus CIDR) to either the GnRH group (GnRH on day 0, PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 28), the CIDR group (CIDR insert from days 0 to 7, PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 34), the GnRH + CIDR group (GnRH on day 0, CIDR insert from days 0 to 7, PGF2alpha on day 7, GnRH on day 9 and TAI 16h later, n = 32), and the control group (PGF2alpha on day 7, GnRH on day 9 and TAI 16 h later, n = 28). For cows without a CL, plasma P4 concentrations were determined on days 0, 7, 10 and 17 and ovarian structures determined on days 0, 7 and 17. Pregnancy rates were evaluated at 30, 55 and 90 d after the resynchronized AI. For cows in diestrus, there were no differences in pregnancy rates on days 30, 55 and 90 for cows in the GnRH (27.5, 26.5 and 24.2%) or ECP (29.1, 25.5 and 24.1%) groups. In addition, there were no differences in pregnancy losses between days 30 and 55 and 55 and 90 between the GnRH (7.0 and 8.6%) and ECP (9.8 and 5.4%) groups. For cows without a CL, GnRH on day 0 increased the proportion of cows with a CL on days 7 and 17 and plasma P4 concentration on day 17 in cows with ovarian cysts but not for cows in proestrus. The CIDR insert increased pregnancy rate in cows with ovarian cysts but reduced pregnancy rate for cows in proestrus.

Pregnancy rates were compared in lactating dairy cows (n = 1083) assigned to protocols for resynchronization of ovulation based on stages of the estrous cycle, or presence of ovarian cysts or anestrus. Cows were detected not pregnant by ultrasonography 30 d after a previous AI (study day 0) and classified as diestrus, metestrus, proestrus, with ovarian cysts or anestrus. Cows in diestrus (January-May) were assigned to either Ovsynch (GnRH day 0, PGF2alpha day 7, GnRH day 9, and timed-AI [TAI] 16 h later; n = 96), or Quicksynch (PGF2alpha day 0, estradiol cypionate [ECP] day 1, AI at detected estrus [AIDE] on day 2, or TAI on day 3; n = 96). Cows in diestrus (June-December) were assigned to either Ovsynch (n = 156) or Modified Quicksynch (PGF2alpha day 0, ECP day 1, AIDE days 2 and 3, and to Ovsynch on day 4 if not detected in estrus; n = 142). Cows in metestrus were assigned either to Ovsynch (n = 68), Heatsynch (GnRH day 0, PGF2alpha day 7, ECP day 8, AIDE day 9, or TAI day 10; n = 62), or GnRH + Ovsynch (GnRH on day 0, followed by Ovsynch on day 8; n = 64). Cows in proestrus, with ovarian cysts, or anestrus were assigned to either Ovsynch (proestrus n = 89, ovarian cysts n = 97, anestrus n = 8) or GnRH + Ovsynch (proestrus n = 87, ovarian cysts n = 109, anestrus n = 9). Pregnancy rate was evaluated 30, 55 and 90 d after resynchronized AI. For cows in diestrus (January-May), pregnancy rates were higher for Ovsynch (35.9, 29.2 and 26.0%) than for Quicksynch (21.7, 16.7 and 15.6%). For cows in diestrus (June-December), pregnancy rates were similar for Ovsynch (34.4, 24.0 and 23.6%) and Modified Quicksynch (27.1, 26.2 and 21.6%). For cows in metestrus, pregnancy rates were higher for GnRH + Ovsynch (33.3, 24.5 and 20.3%) than for Heatsynch (20.3, 12.9 and 9.8%). For cows with ovarian cysts, pregnancy rates were higher for GnRH + Ovsynch (30.3, 26.6 and 22.9%) than for Ovsynch (20.2, 18.5 and 14.7%). Assignment to resynchronization protocols based on the stages of the estrous cycle, or presence of ovarian cysts improved pregnancy rates.

The objective was to compare pregnancy rates and pregnancy losses in lactating dairy cows that were diagnosed not pregnant and re-inseminated following either the Ovsynch or Heatsynch protocols. Also evaluated were the effects of stages of the estrous cycle, ovarian cysts and anestrus on pregnancy rates for both treatments. Non-pregnant cows (n = 332) as determined by ultrasonography on day 27 post-AI (study day 0) were divided into two groups. Cows in the Ovsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, GnRH on day 9, and timed AI (TAI) 16 h later (day 10). Cows in the Heatsynch group (n = 166) received GnRH on day 0, PGF2alpha on day 7, estradiol cypionate (ECP) on day 8, and TAI 48 h later (day 10). Cows detected in estrus on days 8 and 9 were inseminated and included in the study. On day 0, cows were classified according to different stages of the estrous cycle, or presence of ovarian cysts or anestrus. Pregnancy rates were evaluated 27, 45 and 90 days after resynchronized AI. Overall, there was no difference in pregnancy rates on days 27, 45 and 90 between cows in the Ovsynch (25.2, 17.5, and 13.9%) and Heatsynch (25.8, 19.9, and 16.1%) groups. There was no difference in pregnancy losses from days 27 to 45 and days 45 to 90 for cows in the Ovsynch (25.0 and 17.9%) and Heatsynch (14.7 and 10.3%) groups. However, pregnancy rates were increased when cows in metestrus were subjected to the Heatsynch protocol and cows with ovarian cysts were subjected to the Ovsynch protocol.

The objective of this study was to determine the effect of GnRH (100 microg i.m.) treatment 5 and 15 days after timed insemination (TAI) on pregnancy rate and pregnancy loss in lactating dairy cows subjected to synchronization of ovulation. The study included 831 lactating dairy cows subjected to a Presynch-Ovsynch protocol for first service. On the day of TAI (Day 0), cows were randomly assigned to one of four experimental groups. Cows in Group 1 (n = 214) were treated with GnRH on Day 5; cows in Group 2 (n = 209) were treated with GnRH on Day 15; cows in Group 3 (n = 212) were treated with GnRH on both Day 5 and Day 15; cows in Group 4 (n = 196) were not treated. Pregnancy rate was evaluated at Day 27 and Day 45 after TAI. The interestrus interval and the proportion of cows diagnosed not pregnant based on expression of estrus and insemination before pregnancy diagnosis on Day 27 were determined. The results of this study are: (1) GnRH treatment on Day 5 or Day 15 did not increase pregnancy rate, or reduce pregnancy loss between Day 27 and Day 55 after TAI; (2) cows treated with GnRH on both Day 5 and Day 15 had a lower (P < 0.01) proportion of cows diagnosed not pregnant based on expression of estrus before ultrasonography on Day 27 (26.5%) compared to control cows (52.9%), and these cows had an extended (P = 0.05) interestrus interval (23.4 days vs. 21.5 days); and (3) GnRH treatment on both Day 5 and Day 15 after TAI reduced pregnancy rate on Day 27 (36.8% vs. 44.4% for control cows; P < 0.03) and Day 55 (28.3% vs. 36.2% for control cows; P < 0.01). Therefore, strategies to stimulate CL function using multiple doses of GnRH during the luteal phase need to consider potential negative effects.

The objective was to determine the effect of biostimulation (bull-exposure) on uterine involution (UI), plasma progesterone concentration (P4), size of largest follicle (LF), number of follicles larger than 5 mm ( F > or = 5 ), presence of fluid in uterine lumen (PF), presence of luteal tissue (LT), and length of the first estrous cycle postpartum (LEC). Ninety Angus cows with calves were allocated by parity and body frame into three groups (30 per group) 1 week postpartum. Two groups were exposed to bulls (BE) and one non-exposed group (NE) served as a control. Data were collected during weekly sessions of palpation per rectum, ultrasonography and bleeding on a subgroup of 30 cows (10 cows per group) for 6 weeks, and permanent surveillance of estrus with HeatWatch on all 90 cows. There were no significant differences between BE and NE cows for UI ( 17.1+/-1.1 days versus 20.1+/-1.6 days), LF ( 9.5+/-1.7 mm versus 11.0+/-2.4 mm), F > or = 5 ( 1.20+/-0.3 versus 1.47+/-0.09 ), and PF. However, LT was detected in more BE than NE cows (13 versus 2; P<0.001 ). Overall differences in P4 were found between BE and NE cows with detected LT ( 2.00+/-0.3 ng/ml versus 1.05+/-0.4 ng/ml, respectively; P<0.05 ). More BE cows resumed reproductive cyclicity with estrous cycles normal in length compared with NE cows (16/30, 53%; 16/30, 53%; and 8/30, 26.6%, for the two BE groups and the NE group, respectively; P<0.01 ). In conclusion, BE hastened luteal function but did not affect uterine involution.

The objective of this study was to evaluate ovarian function after inducing ovulation with a deslorelin implant in nonlactating dairy cows and heifers. Cattle received GnRH on Day -9, and PGF2alpha on Day -2. On Day 0, in Experiment 1, cows received either 100 microg GnRH (Control), a 750 microg (DESLORELIN 750) or 1000 microg (DESLORELIN 1000) deslorelin implant. On Day 0, in Experiment 2, cows received 100 microg of GnRH or a 450 microg (DESLORELIN 450) deslorelin implant. In Experiments 1 and 2, cows received PGF2alpha on Day 16. Ultrasonography and blood sampling for plasma progesterone (P4) were used to monitor ovarian activity. On Day 0, in Experiment 3, heifers received either 100 microg of GnRH or 750 microg (DESLORELIN 750) deslorelin implant. On Day 16, all heifers received PGF2alpha. Blood samples were collected on Days 7, 13 and 16. In Experiments 1-3, deslorelin implants did not elevate plasma concentrations of P4 in a systematic manner during the late luteal phase. In Experiments 1 and 2, deslorelin implants decreased the size of the largest follicle and the number of Class II and III follicles. In Experiments 1 and 2, deslorelin-treated cows failed to ovulate by Day 28. In conclusion, deslorelin implants induced ovulation, stimulated development of a normal CL, and delayed follicular growth during the subsequent diestrus period. For future applications, the dose of the deslorelin implant will have to be adjusted, and if used for timed-inseminations, nonpregnant cows will have to be resynchronized to minimize delayed returns to estrus and ovulation.

The objective of this study was to determine the effect of pretreatment with bovine somatotropin (bST) and/or gonadotropin-releasing hormone (GnRH) 7 days prior to initiation of a protocol for synchronization of ovulation and timed insemination (Ovsynch) on conception rate (CR) of cows with ovarian cysts. A total of 254 lactating dairy cows with ovarian cysts was divided into four groups (Day 0). On Day 0, cows in Group 1 (n = 61) were pretreated with 500 mg bST, s.q., and 100 microg GnRH, i.m.; cows in Group 2 (n = 73) were pretreated with 100 microg GnRH, i.m.; cows in Group 3 (n = 59) were pretreated with 500 mg bST, s.q.; and cows in Group 4 (n = 61) received no pretreatment. All cows were subjected to the Ovsynch protocol 7 days later. All cows previously received routine bST treatment every 14 days until milk production decreased to a minimum level established by the management of the herd. CR was assessed using logistic regression after adjusting for timing of concurrent bST treatment relative to Day 0, parity, season at time of insemination, and days in milk (DIM) on Day 0. CR for cows in Group 3 (12%) was significantly lower (P < 0.05) than that for cows in Group 4 (27%), and CR for cows in Group 1 (18%) and Group 2 (15%) tended to be lower (P < 0.10) than that for cows in Group 4 (27%). From the results of this study, it was concluded that bST pretreatment decreased CR, and pretreatment with GnRH, and GnRH with bST tended to decrease CR in lactating dairy cows with ovarian cysts concurrently treated with bST and subjected to the Ovsynch protocol., (Copyright 2002 Elsevier Science Inc.)

The objective of this study was to determine the effectiveness of testosterone in suppressing estrus in the bitch, and of cabergoline in shortening the length of the subsequent anestrous period. In Experiment 1, 12 diestrual Beagle bitches were randomly divided into two groups when plasma progesterone (P(4)) concentration was <1 ng/ml (Day 0). Starting on Day 0, bitches in Group 1 (n=6) were treated with testosterone cypionate every 14 days for a total of 239 days, and bitches in Group 2 served as untreated controls. On Day 274, bitches in both groups were treated with cabergoline for 40 days and blood samples were obtained on Days 274, 276 and 279 for determination of plasma prolactin (PRL) concentrations using RIA. All bitches were observed for proestrual bleeding during treatment with cabergoline. In Experiment 2, 12 Greyhound bitches previously treated with testosterone within the last 6 months were randomly divided into two groups. At the initiation of this experiment, P(4) concentration was determined to verify that all bitches had a concentration of <1 ng/ml (Day 0). Starting on Day 0, bitches in Group 1 (n=6) were treated with cabergoline for 36 days, and bitches in Group 2 (n=6) served as untreated controls. Blood samples were obtained on Days 0, 2 and 5 to determine PRL concentrations. All bitches were observed for proestrual bleeding during treatment with cabergoline. In Experiment 1, one bitch (Group 1) exhibited estrus after treatment with testosterone (1mg/kg body weight) for 43 days, and one bitch (Group 1) exhibited estrus after treatment with testosterone (2mg/kg body weight) for 113 days. None of the other four bitches in Group 1 exhibited estrus during the period of testosterone treatment (239 days). All bitches in Group 2 (control) exhibited estrus during the 239 days of the study. In addition, five of the six testosterone-treated bitches showed signs of proestrual bleeding within an average of 12.6 days (range of 5-25 days) after treatment with cabergoline; and, four of the six nontestosterone bitches showed signs of proestrual bleeding within an average of 28 days (range of 6-46 days). Prolactin concentrations in bitches in both Groups 1 and 2 significantly decreased after treatment with cabergoline. In Experiment 2, one of the six bitches showed signs of proestrual bleeding within 15 days after treatment with cabergoline. From the results of this study, it was concluded that exogenous testosterone was moderately effective (66%) in suppressing estrus in Beagle bitches, and cabergoline was effective in shortening the length of the anestrous period of Beagle bitches whose estrous cycle was previously suppressed with exogenous testosterone, but less effective in shortening the length of the anestrous period in Greyhound bitches previously treated with testosterone to suppress estrus.

The objective of this observational study was to evaluate the association between lameness, ovarian cysts, and fertility in lactating dairy cows. Data analysis of historical records from a 3000 Holstein farm was conducted. Sixty-five cows that became lame within 30 days postpartum were used as cases, and 130 nonlame cows served as controls. The outcome variables were incidence of ovarian cysts (OC, %), conception rate at first service (CRFS, %), overall pregnancy rate (PR, %), and calving to first service interval (CFSI, day), Incidence of OC and CRFS were analyzed by logistic regression, PR by survival analysis and CFSI by ANOVA. Lame cows had a lower CRFS (17.5% versus 42.6%) and higher incidence of OC (25.0% versus 11.1%) than controls (P0.05). There was a multicollinearity relationship between lameness and ovarian cysts. The results show that cows that became lame within the first 30 days postpartum were associated with a higher incidence of ovarian cysts, a lower likelihood of pregnancy, and lower fertility than control cows. Because this is an observational study it is not possible to conclude a cause-effect relationship.

The benefit of using timed-insemination in lactating dairy cows for the treatment of ovarian cysts lies in the fact that cows do not have to be detected in estrus for insemination and achieving pregnancy. We compared the effectiveness of synchronization of ovulation with timed-insemination and induction of estrus with insemination at estrus in the treatment of bovine ovarian cysts in lactating dairy cows. After Day 65 post partum, a total of 368 lactating dairy cows was divided into 3 groups. Cows in Group 1 (n = 209, normal, noncystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and 100 ug, i.m. GnRH on Day 9 and then were time-inseminated 16 h later. Cows in Group 2 (n = 76, abnormal, cystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and 100 ug, i.m. GnRH on Day 9 and time-inseminated 16 h later. Cows in Group 3 (n = 83, abnormal, cystic) were treated with 100 ug, i.m. GnRH on Day 0; 25 mg, i.m. PGF2 alpha on Day 7; and inseminated at induced estrus within 7 d after treatment with PGF2 alpha. Day 0 was the day of initiation of the study. Conception and pregnancy rates among groups were compared using logistic regression and adjusted for parity, time of year and days in milk. Conception and pregnancy rates of Group 1 cows (31.5%) were not significantly different from those of Group 2 cows (23.6%). However, the pregnancy rate in normal cows (Group 1) was higher (P < 0.01) than in cystic cows (Groups 2 and 3). Cows in Group 3 had a higher conception rate than cows in Group 2 (51.7% > 23.6%; P < 0.01). However, pregnancy rates for cows in Groups 2 (23.6%) and 3 (18%) were not significantly different. The finding indicated that synchronization of ovulation and timed-insemination resulted in pregnancy rates similar to those of synchronization of estrus and insemination at an induced estrus within 7 d for the treatment of ovarian cysts in lactating dairy cows.

Two experiments were performed to investigate relationships between oxytocin, prostaglandin release, uterine emptying and fluid accumulation in the uterus. In Experiment 1, the effect of oxytocin on the pattern of prostaglandin release during uterine clearance of radiocolloid was measured in 5 normal mares and 5 mares with delayed uterine clearance. Uterine clearance was measured during estrus by scintigraphy at 0, 60 and 120 min after colloid infusion. After the 120-min reading, 20 IU, i.v., oxytocin were given, and the amount of colloid cleared was measured at 135, 150 and 180 min. Plasma was obtained prior to and during scintigraphy at 5- and 15-min intervals to measure concentrations of 15-keto-13,14-dihydro-PGF2 alpha metabolite (PGFM) by RIA. In Experiment 2, plasma PGFM levels were compared after administration of oxytocin in 8 normal mares and 6 mares with delayed uterine clearance to determine if intrauterine fluid stimulated prostaglandin release. Mares received 2 treatments in a cross-over design. Treatment 1 consisted of 20 IU, i.v., oxytocin during estrus. Treatment 2 consisted of an infusion of 10 mL, i.u., saline 15 min prior to oxytocin administration. Treatments were performed 4 to 6 h apart. Blood was collected and PGFM was measured as in experiment 1. Data were analyzed by least squares analysis of variance. In Experiment 1, regression analysis of scintigraphy and PGFM profiles indicated that time response curves differed between groups (P < 0.01). At 120 min, normal mares retained 40.4 +/- 4.9% (mean +/- SEM) of the radiocolloid while mares with delayed clearance retained 88 +/- 5%. Fifteen minutes after oxytocin administration (135 min), all normal mares and 4 of 5 mares with delayed clearance retained only < 6% of the colloid. During the first 120 min, plasma PGFM concentrations did not differ between the 2 groups. After oxytocin was given, plasma PGFM concentrations increased in 4 of 5 mares with delayed uterine clearance (80 to 3,096 pg/mL) but not in normal mares (13 to 46 pg/mL). In Experiment 2, plasma PGFM concentrations did not rise in normal mares but rose in 3 of 6 mares with delayed clearance (135 to 483 pg/mL) independent of treatment or period. The results suggest that intrauterine clearance of radiocolloid after oxytocin administration appears to be independent of PGF2 alpha release in normal mares during estrus. The difference in prostaglandin release response after oxytocin administration between the 2 groups was unrelated to the presence of intrauterine fluid.

Intrauterine pressure was measured in 4 reproductively normal mares and 4 mares with delay in uterine clearance after administration of oxytocin to determine if intrauterine pressure varied between dosage and group. Changes in intrauterine pressure were measured during estrus, when a follicle was > or =35 mm, using a Millar "Mikro-tip" catheter that had 3 discrete pressure sensors/channels. Mares received 4 different treatments of 10, 5, 2.5 or 0 IU (vehicle) of oxytocin. The protocol for each treatment consisted of a 10-min baseline recording, administration of treatment and measurement of changes in intrauterine pressure for 65 min. After administration of the first two treatments, mares were rested for 2 h and the protocol repeated for the remaining 2 treatments. Changes in intrauterine pressure were measured on a physiograph and stored in a computer. The results were analyzed by 4x4 Latin Square Design analysis of variance (ANOVA) using the GLM procedure of the Statistical Analysis System. The ANOVA detected a main effect of treatment (P<0.01) and mare (nested within group; P<0.01) but no effect of channels, group or treatment-by-group interaction. There was a dose-dependent increase in uterine activity in both normal mares and those with delayed uterine clearance. A dose of 10 IU of oxytocin induced a larger number of uterine contractions (5.67+/-0.06) for a longer time (24.09+/-1.18 min) than the 5 IU (4.16+/-0.06 contractions and 16.31+/-1.18; P<0.01 min) or 2.5 IU dose (4.08+/-0.06 contractions and 17.61+/-1.18 min). The first intrauterine wave occurred most often near the tip of the horn in 10 of 12 recordings in normal mares and in 8 of 12 recordings in mares with delayed uterine clearance. It was then propagated from the middle of the horn to the uterine body just cranial to the cervix. There was no pattern of propagation for subsequent intrauterine pressure waves. We conclude that the difference in spontaneous clearance of the uterus between the 2 groups is not reflected in their response to exogenous oxytocin as determined by changes in intrauterine pressure.

The objective of this study was to determine the reproductive performance of lactating dairy cows treated with GnRH and/or PGF2a for synchronization of estrus and ovulation. Between Days 43 and 57 post partum, a total of 374 dairy cows was divided into 4 groups. Cows in Group 1 (n = 62) were treated with 25 mg, i.m. PGF2a on Days 43 and 57; cows in Group 2 (n = 65) were not treated at this time; cows in Group 3 (n = 118) were treated with 100 ug, i.m. GnRH on Day 50, 25 mg, i.m. PGF2a on Day 57, 100 ug, i.m. GnRH on Day 59, and time-inseminated 16 h later; cows in Group 4 (n = 129) were treated with 25 mg, i.m. PGF2a once on Day 57. Cows in Groups 1 and 4 were inseminated at an induced estrus within 7 d after the last PGF2a treatment, and cows in Group 2 were inseminated at a noninduced estrus within a corresponding period of time. Conception rate, estrus detection rate and pregnancy rate were analyzed using logistic regression, and controlled for lactation number, body condition score and time of year. Days from calving to conception were analyzed using the GLM procedures of SAS, and the model included group, body condition score, lactation number, time of year, and their interactions. Cows in Group 3 had a significantly higher pregnancy rate than cows in Groups 1, 2 and 4. Orthogonal contrasts of mean days from calving to conception showed that cows in Group 3 had significantly (P < 0.01) less days from calving to conception than cows in Group 1 and Group 4. There was a significant effect of time of year on pregnancy rate and days from calving to conception, but there was no interaction between time of year and these reproductive characteristics. There was no effect of body condition score and lactation number on the reproductive characteristics evaluated. From the results of this study, it was concluded that better reproductive performance was observed in cows inseminated at a synchronized ovulation than in those inseminated at a synchronized estrous period.

The objective of this study was to determine the value of using plasma concentrations of PGFM to diagnose subclinical endometritis in the dairy cow, and its relationship to subsequent fertility. A total of 274 cows between 24 to 29 d post partum was divided into 4 groups on the basis of clinical features of the uterus and ovary. Cows in Group 1 (n = 74) had a normal, involuting uterus and a CL on the ovary; cows in Group 2 (n = 51) had a normal, involuting uterus but no CL on the ovary; cows in Group 3 (n = 83) did not have a normal, involuting uterus but had a CL on the ovary; and cows in Group 4 (n = 66) did not have a normal, involuting uterus or a CL on the ovary. A blood sample was obtained from each cow on the day they were placed on the study, and plasma concentrations of PGFM and P4 were determined using RIA. Cows were artificially inseminated (AI) at the first observed estrus after Day 60 post partum, and pregnancy was determined by palpation of the uterus per rectum between 45 and 50 d postAI. Reproductive responses evaluated were conception rate to first service, days open, and percentage of cows pregnant by 90, 120, 150 and 180 d post partum. Data were analyzed using GLM procedures of SAS and a 2 x 2 factorial with contrast procedures. Polynomial regression analysis was used to determine the shape of the PGFM, P4 and fertility curves. There was no difference among mean PGFM concentrations of cows in each group. The rate of decline of plasma PGFM concentrations was lower in cows with an abnormal uterus and a CL on the ovary compared with those without a CL. A lower percentage of cows with abnormal uteri was pregnant by 90 d post partum compared with cows with normal uteri. From the results of this study, it was concluded that plasma PGFM concentrations between Days 24 to 29 post partum were not effective in identifying cows with subclinical endometritis.

The objective was to determine whether occurrence of persistent corpora lutea in cows with pyometra could be explained by accumulation of prostaglandins and interferons in the uterus. Pyometra was induced by treatment with hCG, followed by intrauterine infusions of iodine and Actinomyces pyogenes . Five of the seven treated cows developed pyometra as indicated by extended estrous cycles (30-37 + d) and presence of purulent uterine exudate at slaughter (Day 37 after estrus). Mean (+/- standard error) concentrations of prostaglandins E(2) and F(2alpha) for the cows with pyometra were 34.7 +/- 14.4 and 96.3 +/- 28 ng/ml, while the concentrations in uterine flushings in the remaining 2 cows averaged 1.85 +/- 0.7 and 0.9 +/- 0.2 ng/ml, respectively. Based on Western blotting, none of the cows had detectable concentrations of either interferon-alpha or interferon-tau in uterine secretions. In conclusion, pyometra results in increased uterine prostaglandin secretion. While increased secretion of cytokines associated with bacterial infection may be contribute to this effect, there was no evidence in this study to suggest that interferons are involved in the mechanism which causes persistence of the corpus luteum in bovine pyometra.

A total of 335 lactating dairy cows was used to determine the effect of oxytocin or PGF2a given 8 h after treatment with a luteolytic dosage of PGF2a on the percentage of cows exhibiting estrus within 7 d after treatment, and the pregnancy rate to a single insemination at this time. On the initial day of treatment (Day 0), cows with a palpable corpus luteum on the ovary were treated with 25 mg, im of PGF2a. At 8 h later, the cows were divided into 3 groups. Cows in Group 1 (n = 112) were treated with oxytocin (0.33 IU/kg bwt im); cows in Group 2 (n = 112) were treated with 25 mg, im of PGF2a; and cows in Group 3 (n = 111) served as the untreated controls. Cows in all 3 groups were continuously observed for estrus visually or by way of an activated heatmount detector within 7 d after treatment, and were inseminated within 12 h of the observed estrus.Plasma progesterone (P4) concentration was determined using radioimmunoassay on Day 0 and Day 2. Of the cows with P4 greater than 1 ng/ml on Day 0, the percentage of cows observed in estrus within 7 d after treatment was 75, 89 and 72% for cows in Group 1, Group 2 and Group 3, respectively. When all cows were evaluated, the percentage of cows observed in estrus within 7 d after treatment was 60, 70 and 55% for cows in Group 1, Group 2 and Group 3, respectively. In both instances, the value for cows in Group 2 was significantly higher than that for either cows in Group 1 or Group 3. The pregnancy rate for cows inseminated within 7 d was similar for cows in all 3 groups. The results of this study demonstrated that treatment of dairy cows with 2 luteolytic dosages of PGF2a at an 8-h interval resulted in more cows being observed in estrus within 7 d than with 1 treatment with PGF2a, or with oxytocin given at an 8-h interval after a luteolytic dosage of PGF2a.

Holstein cows (n = 445) that had experienced dystocia, retained fetal membrane, or both at parturition were used to determine the effects of GnRH, PGF2 alpha, or both on various reproductive measurements. Cows affected with these conditions were assigned randomly to each of four treatment groups. One group of cows was untreated, and three groups received GnRH once at 12 d postpartum, or GnRH at 12 plus PGF2 alpha at 26 d postpartum, or PGF2 alpha given at 12 and 26 d postpartum. Another group of 191 cows that calved normally were untreated. Conception rate after first AI was higher for cows treated with PGF2 alpha at 12 and 26 d postpartum. Cows affected with dystocia, retained fetal membranes, or both and treated early postparum with GnRH alone or followed 14 d later with PGF2 alpha did not have improved reproductive performance. Cows calving during the summer months of June through September experienced a reduction in the reproductive traits examined.

This study was conducted to evaluate the use of prostaglandin F2alpha (PGF2alpha) in the initial treatment of ovarian cysts in dairy cattle. Two hundred and sixty three cows diagnosed cystic on palpation per rectum were randomly assigned to one of three treatment groups (A, B or C). Cows in Groups A and B were treated with 25 mg i.m.of PGF2alpha at the time of diagnosis (Day 0), while cows in Group C received 100 mug of GnRH. Seven days following initial treatment (Day 7), cows from Group A that were not observed in estrus were treated with GnRH. Cows from Groups B and C were not treated. On Day 14, all cows that had not been inseminated received PGF2alpha. A blood sample was obtained from all cows on Days 0, 7 and 14 and was analyzed for progesterone (P4) using radioimmunoassay. Incidences of estrus were recorded and cows that were more than 60 d in milk at the time of diagnosis were bred when observed in estrus. The incidence of follicular cysts on Day 0 (as defined as P4 <0.5 ng/ml) was similar between groups and constituted about 40% of all cysts. There were significantly more cows pregnant to insemination within 7 d of initial treatment in Group B than in Groups A and C (P<0.05). After Day 14, the pregnancy rate was not statistically different between Group B and C, but Groups B and C had a statistically higher pregnancy rate than Group A from Day 21 to Day 35. At the end of the study, there was no statistical difference for the pregnancy rate between groups. We concluded that treatment of ovarian cysts diagnosed by per rectum examination with prostaglandin (at time of diagnosis and 14 d later for cows that were not inseminated) was as effective as initial treatment with GnRH followed by prostaglandins 14 d later for cows that were not inseminated previously. Cows that were initially treated with prostaglandins also tended to become pregnant sooner.

A total of 329 cows was used in 2 experiments to study the effect of PGF2a given 8 or 24 h apart on the number of cows observed in estrus within 7 d and the pregnancy rate to a single insemination at this time. In Experiment 1, 233 cows were divided into 2 groups. Cows in Group 1 (n = 117) were treated twice with 25 mg, im of PGF2a (0 and 8 h) while cows in Group 2 (n = 116) were treated only once (0 h). In Experiment 2, 96 cows were divided into 2 groups. Cows in Group 1 (n = 49) were treated twice with 25 mg, im of PGF2a (0 and 24 h) while cows in Group 2 (n = 47) were treated only once (0 h). In Experiment 1, blood samples were obtained from cows in both groups on Days 0 and 2. However, in Experiment 2, blood samples were obtained from cows in both groups only on Day 0. Plasma progesterone concentration was determined using radioimmunoassay. Cows in both experiments were observed for estrus within 7 d of treatment and were inseminated within 12 h of the observed estrus. In Experiment 1, more cows in Group 1 were observed in estrus within 7 d than in Group 2 (P <0.03). In Experiment 2, there was no significant difference in the number of cows in both groups that were observed in estrus within 7 d. However, the interval from treatment to the first observed estrus for cows not observed in estrus within 7 d was significantly longer in cows treated at 0 and 24 h compared with the cows treated once at 0 h. In both experiments, the pregnancy rate for cows inseminated within 7 d was similar for cows in all groups. From the results of this study, it is concluded that treatment of dairy cows with 2 luteolytic dosages of PGF2a at an 8-h interval resulted in more cows being observed in estrus than at a 24-h interval.

A total of 585 repeat-breeder dairy cows was used to study the effect of GnRH treatment, either at or prior to insemination, on the pregnancy rate. The cows were divided into 6 treatment groups. Cows in Group 1 (n = 142) were observed in estrus, and 11 +/- 0.42 hours (mean +/- SEM) later they were given 100 ug, i.m. gonadotropin releasing hormone (GnRH) and were inseminated. Cows in Group 2 (n = 139) were observed in estrus and were inseminated 11.4 +/- 0.43 hours later. Cows in Group 3 (n = 33) were monitored for estrus with an activated heatmount detector but were not observed in estrus; they were inseminated 1.5 +/- 0.87 hours later and were given 100 ug, i.m. GnRH. Cows in Group 4 (n = 35) were not observed in estrus, but they did activate the heatmount detector and were inseminated 2.2 +/- 0.87 hours later. Cows in Group 5 (n = 107) were observed in estrus, given 100 ug, i.m. GnRH 2.0 +/- 0.40 hours later, and were inseminated 9 +/- 0.60 hours after GnRH treatment. Cows in Group 6 (n = 129) were observed in estrus and were inseminated 10 +/- 0.50 hours later. Pregnancy rates were analyzed by Chi-square. Interactions between pregnancy rate, treatment and time of insemination were evaluated using ANOVA and LSM (P < 0.05). There was no effect on pregnancy rate when GnRH was given at or prior to insemination. Cows inseminated on the basis of observed estrus had a higher pregnancy rate (P < 0.05) than cows inseminated on the observation of an activated heatmount detector. From the results of this study, it is concluded that treatment with GnRH at or prior to insemination did not improve the pregnancy rate of repeat-breeder dairy cows.

This study was designed to determine conception rates in dairy cows after timed-insemination and simultaneous treatment with gonadotrophin releasing hormone (GnRH) and/or prostaglandin F2 alpha (PGF2alpha). A total of 2352 cows was randomly assigned to six groups. Cows in Groups 1 to 5 were palpated per rectum to determine the presence of a corpus luteum (CL) on the ovary, and blood samples were obtained for the determination of plasma progesterone (P4) concentrations. Cows with a CL and P4 concentrations >1 ng/ml were treated (Day 0) with PGF2alpha (25 mg, i.m.) and were observed for estrus. Cows in estrus prior to 72 hours after treatment (Group 5, n = 106) were bred, but were not treated. Cows not observed in estrus by 72 hours were divided into four remaining groups, were bred between 72 and 80 hours and were assigned as follows: Cows in Group 1 (n = 203) were not treated; Cows in Group 2 (n = 200) were treated with GnRH (100 ug, i.m.); Cows in Group 3 (n = 201) were treated with PGF2alpha (25 mg, i.m.); and cows in Group 4 (n = 202) were treated with both GnRH and PGF2alpha. Cows in Group 6 (n = 1440) were not treated with PGF2alpha on Day 0 and were estrual cows that were bred on days when cows in Groups 1 to 5 were time-inseminated. The percentage of cows in all groups pregnant at 45 to 50 days after one insemination was compared using analysis of variance (P<0.05). The conception rate of cows in Group 2 was significantly higher than that of cows in Groups 1 to 4. There was a significant group-by-season interaction. Cows treated with GnRH during the spring had a higher conception rate than at other times of the year. Conception rates of cows in Groups 1 to 4 that were inseminated during the summer were low and not significantly different from each other. Conception rates of cows in Groups 5 and 6 inseminated during the summer were not significantly different from each other, but were significantly higher than that of cows in Groups 1 to 4 that were inseminated during the summer.

The objectives of this study were to determine 1) the incidence of abnormal postpartum ovarian function in a large dairy herd in North Central Florida and 2) the effectiveness of gonadotrophin releasing hormone (GnRH) in treating this condition. The study was conducted from April 1988 to June 1989. The internal genitalia of the cows were initially examined per rectum (Day 0) between 19 and 29 (23 +/- 0.25) d after calving and again 14 d later (Day 14) for evidence of uterine involution and ovarian activity. The presence of a palpable corpus luteum (CL) and retrospective determination of plasma progesterone (P4) concentrations > 1 ng/ml were the criteria used to assess ovarian activity. Cows possessing a palpable CL and P4 concentrations > 1 ng/ml on Day 0 were determined to be cycling normally. A total of 1356 cows was used in this study. On Day 0, two groups were formed: Group 1 consisted of normal, cyclic cows, Group 2 of noncyclic cows. On Day 0, alternate cows in Group 2 were treated with GnRH (100 microg i.m). On Day 14, the previously nontreated cows in Group 2 were further divided into two groups, forming Group 3, nontreated cows and Group 4, cows treated with GnRH at this time. Group 5 was comprised of cows from Group 2 that did not respond to treatment with GnRH on Day 0; these cows were treated on Day 14 with GnRH (100 microg i.m). Group 6 was comprised of nontreated cows from Group 2 that responded spontaneously (presence of a CL) by Day 14. Reproductive parameters evaluated were the percentage of cows pregnant within 180 d after calving and at the end of the study, the number of days open and the number of services per conception. Data were statistically analyzed using Chi square and survival analysis. The results of this study indicate that the incidence of abnormal postpartum ovarian function in this herd was 30.2% and that the nontreated cows experienced more days open and required more services per conception than the treated cows, those that were cycling normally on the initial examination, and those that responded spontaneously by Day 14.

Monolayers of bovine fetal endometrial cells were established as primary culture cells within 1 to 2 weeks. After the 2nd passage, these cells were inoculated with bovine viral diarrhea virus. Effects of the virus were observed each day with a light microscope. Specific cytopathic effects consisting of degeneration and sloughing of the cells and a well-defined pattern of cytoplasmic vacuolation were observed at 5 days after inoculation.

Twelve cycling Angus-based crossbred cows were used in a crossover experimental design to evaluate two different injection schedules using Follicle Stimulating Hormone (FSH) for superovulating donor cattle. Females randomly assigned to Treatment (A) were given twice daily FSH injections of 5 mg each (12 hours apart) for five consecutive days starting on day 10 of the estrous cycle while those in Treatment (B) received the same daily dose level of FSH, except it was given in a 3.2% protein gelatin carrier vehicle and administered on a once daily injection schedule. Animals in both Treatments (A) and (B) were each given a 30 mg dose of commercially available prostaglandin-F(2alpha) agent 48 hours after the first FSH injection. Cows in estrus were initially handmated to a fertile bull then artificially inseminated 12 hours later with two units of frozen semen. All 12 animals (100%) given twice daily FSH injections and 11 of the females (91.6%) administered once daily FSH injections exhibited standing estrus within 5 days following injection of the luteolytic agent. On day 7 or 8 after the onset of standing estrus a laparotomy was performed to observe ovarian structures. When the superovulation response was evaluated, the mean number of corpora lutea per ovary ranged from 2.9 in the twice daily injection group to 4.1 in the once daily injected group. Unexpectedly, the once daily treated group had significantly more corpora lutea per animal (8.1 vs. 6.4) than those in the twice daily treated group. In addition, mean ovarian size score per animal increased significantly when pre-treatment scores were compared to those recorded following FSH treatment (laparotomy) in both Treatment (A) and (B), however, the post-treatment ovarian size scores were not different between these groups. When evaluating post-treatment follicular development, the once daily injection group had significantly more smaller follicles (<10 mm) and a greater number of ovulatory size follicles (>10 mm) than the twice daily injection group. Furthermore, viable appearing embryos were recovered from both treatment groups and no adverse reactions were observed with the gelatin carrier vehicle in Treatment (B). Since the once daily FSH injection schedule resulted in a superovulatory response equal to or greater than the twice daily FSH injection schedule, this approach to superovulation should not be overlooked by those involved in bovine embryo transplantation.