Comparison of a conventional reproductive management programme based on rectal palpation and uterine treatment of endometritis with a strategic prostaglandin F2 alpha programme

Effect of diagnosis and treatment of clinical endometritis based on vaginal discharge score grading system in postpartum Holstein cows

In this study, the prevalence, effectiveness of diagnosis, and treatment based on vaginal discharge score (VDS) of clinical endometritis in cattle were evaluated. To detect clinical endometritis and classify its severity, vaginoscopy was performed during 21 to 60 days postpartum in 164 Holstein cows consisting of 229 lactations. Groups were defined using the 4-point VDS scale. Study groups included the following: non-endometritis (VDS=0; no/clear mucus; NEM group; n=168); mild endometritis, no treatment (VDS=1; mucus containing flecks of white/off-white pus; NTR group; n=30); and severe endometritis, treated with PGF2α (VDS≥2; discharge containing <50% pus; and VDS=3; discharge containing >50% pus, and fluid or uterine horn asymmetry; TEM group; n=31). Cows treated with PGF2α that did not recover (VDS≥1, n=5) received intrauterine procaine penicillin and streptomycin. Prevalence of clinical endometritis (VDS≥1) was 26.6%. The NTR group required significantly more artificial inseminations per pregnancy than NEM and TEM groups (2.8 ± 1.8 vs 2.0 ± 1.3, 1.9 ± 0.8, P<0.05). In survival analysis, the proportion of non-pregnant cows was higher in the NTR group compared to the NEM (P=0.012) and TEM (P=0.076) groups. In the TEM group, calving to first artificial insemination interval tended to be higher in cows treated 41 to 60 days postpartum than cows treated 29 to 40 days postpartum (97.2 ± 27.1 vs 74.4 ± 19.7, P=0.084). Our study suggests that cows with VDS=1 may require treatment to recover fertility. Diagnosis and treatment of clinical endometritis based on a VDS grading system may improve dairy herd reproductive performance.

Treatment of clinical endometritis in dairy cows by previously used controlled internal drug release devices

Postpartum endometritis is considered as one of the diseases that lead to a potential profit reduction in dairy cows. The aims of the present study were to promote follicle growth by a previously used controlled internal drug release (CIDR) device and to evaluate its effect on the likelihood of recovery and the reproductive performance of clinical endometritis (CE) cows. Endometritis was diagnosed using ultrasonographic examination at 31 ± 3 (Day 0 of the experiment) days in milk, and CE cows were included in one of the three experimental groups according to the presence of a CL on their ovaries. Cows without CL on their ovaries received a reused CIDR device, which was previously used for 14 days (CIDR-14, n = 108), or PGF2α (PG-1, n = 112) on Day 0. In the third group, those with CL on their ovaries received PGF2α (PG-2, n = 107) at the same time. Ovarian structures, serum estradiol and progesterone concentrations were measured on Days 0, 7, and 14. Controlled internal drug release devices were removed, and response to treatment was evaluated in all treated cows on Day 14. Diameters of ovarian follicles were 11.61 ± 0.50, 12.46 ± 0.25, and 18.36 ± 0.60 mm on Day 7 and 11.63 ± 0.58, 14.35 ± 0.40, and 21.96 ± 0.77 mm on Day 14 in PG-1, PG-2, and CIDR-14 cows, respectively (P < 0.05). Serum estradiol concentrations were higher in CIDR-14 cows (141.17 ± 1.04 pg/mL) than in PG-1 (116.85 ± 1.05 pg/mL) and PG-2 (119.10 ± 1.05 pg/mL) cows on Day 7 (P < 0.05). Higher progesterone concentrations were observed in PG-2 cows than in PG-1 and CIDR-14 cows on Days 0, 7, and 14 (P < 0.001). The likelihood of clinical cure was 54.46%, 62.61%, and 64.81% in PG-1, PG-2, and CIDR-14 cows, respectively (P = 0.11). First-service conception risk, days to the first service, calving to conception interval, proportion of cows bred and pregnant by 120 days in milk did not differ among the treated groups (P > 0.05). The cumulative pregnancy risk was lower in PG-1 (77.67%) cows than in CIDR-14 (87.07%) and PG-2 (87.85%) cows (P = 0.02). In conclusion, reused CIDR would be contributed to the treatment of CE by promotion of follicle growth and induction of sustainable sources of endogenic estrogen secreted by the dominant follicle.

Efficacy of homeopathic remedies as prophylaxis of bovine endometritis

The objective of this study was to evaluate the efficacy of 2 different homeopathic prophylactic strategies for the prevention of endometritis. The drugs used were Lachesis compositum (Lachesis), Carduus compositum (Carduus), and Traumeel LT (Traumeel). Each drug contained a mixed formula of homeopathic remedies. All 929 cows received the first treatment within 24 h postpartum. The second to fourth treatments were conducted at 7 to 13, 14 to 20, and 21 to 27 d in milk, respectively. In the first group, the 4 treatments were Traumeel, Lachesis, Carduus, and Carduus, respectively (n = 206). In the second group, Lachesis was administered 3 times, followed by 1 treatment with Carduus (n = 198). The control group received 4 injections of saline (n = 189). In the fourth week after calving, the prevalence of clinical endometritis, uterine involution, and ovarian activity was monitored by rectal palpation and by ultrasonography. To assess the resumption of ovarian activity, blood samples were taken to determine the concentration of serum progesterone. The concentrations of beta-hydroxybutyrate and nonesterified fatty acids in blood serum were examined to evaluate energy metabolism. The incidence of clinical endometritis at 21 to 27 d in milk did not differ between the groups (44.4, 44.8, and 36.9% in the Traumeel, Lachesis, Carduus, and Carduus group; the 3x Lachesis, followed by Carduus group; and the control group, respectively). The proportion of cows with cyclic activity at 21 to 27 d in milk and the proportion of cows above threshold values of progesterone, beta-hydroxybutyrate, and nonesterified fatty acids did not differ significantly between groups. When reproductive performance data were analyzed, no significant differences were found between groups. Hence, the treatment protocols tested were not effective in preventing bovine endometritis or in enhancing reproductive performance in this study.

The impact of uterine infection on a dairy cow's performance

The aim of this study was to assess the predisposing factors leading to uterine infection in dairy cows and evaluate its impact on the cow's performance. Performance indicators included feed intake, milk fat and protein composition, milk yield, fertility and culling. Data were studied from 2914 completed lactations from the Holstein Friesian Langhill Dairy herd between January 1990 and August 2005. There were 402 cases of uterine infection (from 321 cows) in the Langhill herd, a level of 13.8% during the study period. Calving assistance was highly associated with the incidence of uterine infection (chi(2)=106.63, P<0.001). Failure to conceive (chi(2)=3.89, P<0.05; chi(2)=11.20, P<0.001) and culling (chi(2)=13.66, P<0.001, chi(2)=8.55, P<0.01) were also implicated with calving assistance and uterine infection, respectively. The main predisposing factors related to an incidence of uterine infection were calving assistance, twin births, malpresented calves, and retained placenta. First-time calvers and cows with a shorter gestation length were associated with more cases of uterine infections. Additionally, lower daily dry matter intakes and milk yields during the first 100 days in milk (DIM) were associated with higher incidence levels of uterine infection. Also, a higher incidence level of uterine infection was related to lower milk protein composition from 1 to 21 DIM and a poorer body condition from 101 to 300 DIM. Cows with poorer drying off body condition scores and longer lactation lengths were associated with a higher incidence level of uterine infection. Calving assistance was associated with male and twin births, first-time calvers and cows with oversized calves. Cows with an assisted calving were also associated with an increased number of days from calving to first service. The predisposing factors influencing the occurrence of calving assistance can be influenced by suitable management to reduce the chances of oversized calves, the detrimental effects of twin births (such as calving assistance and retained placentas) and prenatal knowledge of the calf's sex. The occurrence of uterine infection can be reduced by minimising the need for assistance at calving. Assistance should only be carried out when necessary and appropriate hygiene should be used to decrease the incidence of uterine infections from intervention and involuntary culling due to cows failing to conceive.

Effects of a single administration of prostaglandin F2alpha, or a combination of prostaglandin F2alpha and prostaglandin E2, or placebo on fertility variables in dairy cows 3-5 weeks post partum, a randomized, double-blind clinical trial

BACKGROUND

Delayed uterine involution has negative effects on the fertility of cows; use of prostaglandin F2alpha alone as a single treatment has not been shown to consistently improve fertility. Combined administration of PGF2alpha and PGE2 increased uterine pressure in healthy cows. We hypothesized, that the combination of both prostaglandins would accelerate uterine involution and have, therefore, a positive effect on fertility variables. In commercial dairy farming, the benefit of a single post partum combined prostaglandin treatment should be demonstrated.

METHODS

383 cows from commercial dairy farms were included in this study. Uterine size and secretion were evaluated at treatment 21-35 days post partum and 14 days later. Cows were randomly allocated to one of three treatment groups: PGF2alpha and PGE2, PGF2alpha or placebo. For every animal participating in the study, the following reproduction variables were recorded: Interval from calving to first insemination, days open, number of artificial inseminations (AI) to conception; subsequent treatment of uterus, subsequent treatment of ovaries. Plasma progesterone level at time of treatment was used as a covariable. For continuous measurements, analysis of variance was performed. Fisher's exact test for categorical non-ordered data and exact Kruskal-Wallis test for ordered data were used; pairwise group comparisons with Bonferroni adjustment of significance level were performed.

RESULTS

There was no significant difference among treatment groups in uterine size. Furthermore, there was no significant difference among treatments concerning days open, number of AI, and subsequent treatment of uterus and ovaries. Days from calving to first insemination tended to be shorter for cows with low progesterone level given PGF2alpha and PGE2 in combination than for the placebo-group (P = 0.024).

CONCLUSION

The results of this study indicate that the administration of PGF2alpha or a combination of PGF2alpha and PGE2 21 to 35 days post partum had no beneficial effect upon measured fertility variables. The exception was a tendency for a shorter interval from calving to first insemination after administration of the combination of PGF2alpha and PGE2, as compared to the placebo group. Further research should be done in herds with reduced fertility and/or an increased incidence of postpartum vaginal discharge.

Treatment of chronic endometritis in dairy cows with an intrauterine application of enzymes. A field trial

The use of proteolytic enzymes has been established in the non-antibiotic treatment of mastitis in dairy cattle. The objective of this study was to evaluate, if enzymes are efficacious in the treatment of chronic endometritis. In a controlled field trial, cows with vaginal discharge 21-27 days in milk (DIM) were randomly assigned to two treatment groups. Endometritis was classified into three categories, depending on the type of vaginal discharge: clear mucus with flakes of pus (E1), mucopurulent discharge or fluctuating contents in the uterus (E2), and purulent discharge (E3). In group ENZYMES (n=191), cows received an intrauterine treatment with a salve containing the enzymes trypsin (16 mg), chymotrypsin (16 mg), and papain (8 mg). Cows in group PGF (n=225) were treated with 0.5mg of cloprostenol. Cows that did not show any clinical signs of chronic endometritis were regarded as healthy control group (HC, n=699). In groups ENZYMES and PGF, all cows were re-examined 35-41 DIM. In group ENZYMES, cows were re-treated with enzymes if signs of endometritis were found, while in group PGF all cows received a second dose of cloprostenol, regardless of their clinical findings. Cure rate after the first treatment, defined as the absence of vaginal discharge at the re-examinations, was 59.7 and 68.0% in groups ENZYMES and PGF, respectively (P>0.05). Reproductive performance measures showed no significant differences between the two treatment groups. Service rate was significantly lower for ENZYMES and PGF, respectively, compared to HC. Conception rates to all services and percentages of cows pregnant by 250 DIM were significantly lower in group ENZYMES compared to HC, while no further differences were found between PGF and HC. In both treatment groups, cure rate and reproductive performance measures were better for cows categorized E1 or E2, than for cows categorized E3, respectively. Conception rate to all services for cows with endometritis category E1 was higher in group PGF than in group ENZYMES (P<0.05). The results of this field trial suggest that prostaglandin F(2alpha) is still the treatment of choice for chronic endometritis in dairy cattle.

Endometritis treatment with a PGF2α analog does not improve reproductive performance in a large dairy herd in Argentina

In Argentina, most dairy cows with endometritis are treated with prostaglandin (PGF(2alpha) or its analogs) and insemination is withheld until there are no signs of endometritis. The objective of the present study was to evaluate if this method of managing endometritis enhances reproductive performance. Three experiments were conducted over 4 years in a large farm in the west of Buenos Aires province. In Experiment 1, half of the cows diagnosed with endometritis (>1.5-fold difference in diameter of uterine horns, as determined by rectal palpation) received standard endometritis management (treatment with tiaprost, a PGF(2alpha) analog, rectal palpation every 20 days, and withholding of AI until endometritis apparently resolved) and the other half was untreated, with AI at the first estrus after the voluntary waiting period. Untreated cows were inseminated and conceived 20 days earlier than treated cows, and the pregnancy rate by Day 90 postpartum was higher in the untreated group. In Experiment 2, cows with endometritis were divided into four groups according to the severity of symptoms; within each group, cows were allocated to treatment or control, as in Experiment 1. Although first service conception rate decreased as endometritis severity increased, reproductive performance in treated versus control cows was similar to that of Experiment 1 (with no interaction due to degree of endometritis). Re-evaluation of the treated cow (to confirm uterine "normality") may have been responsible for the delay in conception in both experiments. The objective of Experiment 3 was to determine the effects of tiaprost treatment on clinically normal postpartum cows (no evidence of endometritis). Tiaprost treatment reduced the interval from calving to conception in multiparous cows, but it delayed conception and reduced the conception rate in primiparous cows. In conclusion, treatment with tiaprost impaired reproductive performance in primiparous cows (in the absence of endometritis). Furthermore, the standard treatment for endometritis (treatment with a prostaglandin analog and withholding insemination until clinical signs abated) impaired reproductive performance and increased costs.

A sheer pharmacologic approach to compare the contractile effects of PGF2α, dl-cloprostenol and d-cloprostenol on isolated uterine, tracheal, ileal and arterial smooth muscle preparations

The contractile effects of PGF2alpha and its cloprostenol analogs (D-enantiomer and racemate) were examined on isolated smooth muscle preparations (uterine, tracheal, ileal and arterial) from rat, guinea-pig and horse. DL- and D-cloprostenol were potent contractors of myometrium, but had negligible secondary effects on other types of smooth muscle, except artery whose response to the D-enantiomer may give rise to some concern.

Influence of stage of lactation and milk production on conception rates after timed artificial insemination following Ovsynch

Conception rates after timed artificial insemination (TAI) are of paramount importance for the success of protocols based on synchronization of ovulation. Stage of lactation and milk production level are known factors that influence dairy cow fertility. It was the objective of this study to analyse the effect of stage of lactation and milk production level on conception rates and pregnancy rates by 200 days in milk (DIM) in dairy cows synchronized with the Ovsynch protocol (Day -10, Day -1: 0.1 mg of D-Phe6-gonadorelin, Day -3: 0.5 mg of cloprostenol, Day 0: AI). A total of 1,288 dairy cows were assigned to two groups and classified in three production levels (high, average, low). Cows of all milk production levels in Group 1 (Simultaneous Ovsynch, SO) were synchronized with the Ovsynch protocol simultaneously for TAI between 73 and 81 DIM. In Group 2 cows with average milk production were synchronized at the same time as Group 1, while low producing cows were synchronized 3 weeks earlier and high producing cows were synchronized 3 weeks later than Group 1, respectively. First service conception rates (FSCRs) were lower (P<0.05) in cows synchronized earlier than in cows of the same production level synchronized later (low production: 14.4% (22/153) versus 34.5% (51/148); high production: 28.2% (40/142) versus 41.4% (53/128)). Milk production level had no significant impact on conception rates after TAI in cows synchronized at the same stage of lactation. At 200 DIM fewer cows with high production level were pregnant than cows with average or low production (P<0.05). This effect was independent of the stage of lactation at the initiation of Ovsynch. Endometritis at a postpartum examination did not influence conception rates after TAI. In conclusion, stage of lactation, but not milk production level, has a major influence on conception rates after TAI. Early AI after Ovsynch is less efficient and therefore its return on investment should be evaluated carefully.

Comparison of two protocols for the treatment of retained fetal membranes in dairy cattle

Two protocols for the treatment of retained fetal membranes in dairy cattle were evaluated in a field trial. Cows that retained the fetal membranes for more than 12h were assigned to two treatment groups in an alternating order. In both groups rectal temperature was measured daily for 10 days after enrollment. In Group 1 (n=35) cows with a rectal temperature >or=39.5 degrees C received a systemic antibiotic treatment with 600mg ceftiofur intramuscularly on three consecutive days. No manual removal of the fetal membranes or intrauterine treatment was conducted. In case of elevated temperature of >or=39.5 degrees C on Day 3 treatment was conducted for another 2 days. In Group 2 (n=35) cows received a local antibiotic treatment (2500 mg ampicillin, 2500 mg cloxacillin) and an attempt was made to remove the fetal membranes manually. In case of a rectal temperature >or=39.5 degrees C 6000 mg of ampicillin were administered intramuscularly. Treatment was repeated on three consecutive days. If temperature did not decrease below 39.5 degrees C systemic treatment was extended for another 2 days. During 10 days of observation 33 and 34 cows showed fever, i.e. a body temperature >or=39.5 degrees C in Groups 1 and 2, respectively (94.3 versus 97.1%). The proportion of cows considered as cured (temperature <39.5 degrees C on Day 10 after enrollment) was 65.7 and 68.6% in Groups 1 and 2, respectively. All cows showed signs of chronic inflammation of the genital tract on Day 14 after calving. Within 4 weeks postpartum three (8.6%) and four (11.4%) cows were culled in Groups 1 and 2, respectively. Days to first service and days open did not differ significantly between the groups. Proportion of cows pregnant on Day 200 postpartum was 71.4 and 54.3% for Groups 1 and 2, respectively (P>0.05). Results indicate that treatment of retained fetal membranes without intrauterine manipulation and treatment can be as effective as conventional treatment including detachment and local antibiotic treatment.

The effect of treatment of clinical endometritis on reproductive performance in dairy cows

The objective of this field trial was to compare the effect of intrauterine (i.u.) antibiotic or intramuscular (i.m.) prostaglandin F2 alpha (PGF2 alpha) on time to pregnancy in dairy cows diagnosed with clinical endometritis between 20 and 33 days in milk (DIM). The case definition of endometritis was the presence of purulent uterine discharge or cervical diameter > 7.5 cm, or the presence of muco-purulent discharge after 26 DIM. There were 316 cows with endometritis from 27 farms assigned randomly within herd to receive 500 mg of cephapirin benzathine intrauterine (i.u.), 500 micrograms of cloprostenol i.m., or no treatment. The rate of resolution of clinical signs 14 d after treatment was 77% and was not affected by treatment. Reproductive performance was monitored for a minimum of 7 mo after treatment. Survival analysis (multivariable proportional hazards regression) was used to measure the effect of treatment on time to pregnancy. There was no benefit of treatment of endometritis before 4 wk postpartum. Administration of PGF2 alpha between 20 and 26 DIM to cows with endometritis that did not have a palpable corpus luteum was associated with a significant reduction in pregnancy rate. Between 27 and 33 DIM, cows with endometritis treated with cephapirin i.u. had a significantly shorter time to pregnancy than untreated cows (hazard ratio = 1.63). In this time period, there was no difference in pregnancy rate between PGF2 alpha and untreated cows, but the difference in pregnancy rate between cows treated with cephapirin i.u. and with PGF2 alpha was not statistically significant. Treatment of postpartum endometritis should be reserved for cases diagnosed after 26 DIM, based on criteria that are associated with subsequent pregnancy rate.

Defining and diagnosing postpartum clinical endometritis and its impact on reproductive performance in dairy cows

The objectives of this study were to validate diagnostic criteria for clinical endometritis in postpartum dairy cows and to measure the impact of endometritis on reproductive performance. Data were collected from 1865 cows in 27 herds, including history of dystocia, twins, retained placenta, or metritis. All cows were examined once between 20 and 33 d in milk (DIM) including external inspection, vaginoscopy, and transrectal palpation of the cervix, uterus, and ovaries. All cows were followed for a minimum of 7 mo or until pregnancy or culling. Survival analysis was used to derive a case definition of endometritis based on factors associated with increased time to pregnancy. The significance of clinical findings depended on the interval postpartum when examination took place. The presence of purulent uterine discharge or cervical diameter > 7.5 cm after 20 DIM, or mucopurulent discharge after 26 DIM identified cows with clinical endometritis. Given vaginoscopy, no diagnostic criteria based on palpation of the uterus had predictive value for time to pregnancy. The prevalence of clinical endometritis was 16.9%. Vaginoscopy was required to identify 44% of these cases. Accounting for parity, herd, and ovarian status, cows with clinical endometritis between 20 and 33 DIM had a hazard ratio of 0.73 for pregnancy (took 27% longer to become pregnant), and were 1.7 times more likely to be culled for reproductive failure than cows without endometritis.

Analysis of cow factors influencing conception rates after two timed breeding protocols

The objective of this study was to determine cow factors that influence conception rates after timed artificial insemination (TAI) on a commercial dairy farm. In Trial 1, 197 cows were synchronized by an administration of 25 mg of dinoprost between Days 48 and 54 post partum and again 14 days later. Cows were inseminated 66 and 90 hours after the second treatment. In Trial 2, 186 cows were treated with an Ovsynch protocol consisting of an administration of 0.02 mg of buserelin between Days 62 and 68 post partum, a treatment with 0.75 mg of tiaprost 7 days later and a second treatment with buserelin 48 h later. Cows were bred 16 to 20 hours after the last treatment. Cows with abnormal vaginal discharge at the time of insemination were excluded from AI. Lactation number, milk yield, fat and protein content of milk, signs of endometritis at an examination 14 to 20 days post partum and month of breeding were included as potential factors influencing conception on TAI. Conception rates after timed breeding were 32.0% and 30.6% in Trials 1 and 2, respectively. Logistic regression revealed that neither milk production parameters nor endometritis at post partum examination influenced conception rates in either of the two timed breeding protocols. Only parity showed an effect (P=0.012) in Trial 2. Primiparous cows were more likely to conceive after timed breeding than older cows (43.5 vs. 23.1%). An effect of parity, however, was not observed in Trial 1. It can be concluded that neither milk production nor endometritis at an examination 14 to 20 days post partum influence conception rates after TAI if cows with abnormal vulval discharge at the designated time of AI are excluded from breeding.

Evaluation of a systemic antibiotic treatment of toxic puerperal metritis in dairy cows

The objective of this study was to evaluate the efficacy and economic efficiency of a systemic treatment of toxic puerperal metritis in dairy cows with ceftiofur. Cows with abnormal vaginal discharge at a postpartum examination (d 4 to 6 after calving) and a rectal temperature > or = 39.5 degrees C were assigned to three treatment groups. Cows in group 1 (n = 70) received 600 mg of ceftiofur intramuscularly (i.m.) on 3 consecutive days. Cows in group 2 (n = 79) received an intrauterine treatment with antibiotic pills consisting of 2500 mg of ampicillin and 2500 mg of cloxacillin and an additional 6000 mg (i.m.) of ampicillin. This treatment was performed on 3 consecutive days. Cows in group 3 (n = 78) received the same intrauterine treatment as in group 2. In addition, 600 mg of ceftiofur was administered i.m. on 3 consecutive days. Body temperature was recorded daily for 6 d after first treatment. There were no significant differences among the groups regarding clinical efficacy at d 6 after first treatment. The cure rates based on rectal temperatures declining to below 39.5 degrees C on d 6 after treatment were 82.9, 84.8, and 84.6% for groups 1, 2, and 3, respectively. Reproductive performance did not differ significantly between group 1 and groups 2 and 3 for any of the measures tested. A financial analysis with 87 different cost scenarios demonstrated that a systemic treatment of toxic puerperal metritis in cattle with ceftiofur is an effective alternative to the combination of local and systemic treatments.

Effect of one spontaneous estrus cycle (after synchronization with PGF2alpha) on reproductive performance in dairy cows

The objective of the study was to analyze the effect of a spontaneous estrus cycle after synchronization of estrus with prostaglandin F2alpha (PGF2alpha) in dairy cows on the degree of synchronization and reproductive performance. We assigned 557 Holstein cows to two treatment groups. In Group 1 estrus was synchronized by two treatments with 25 mg of Dinoprost-Trometamol in 14-day intervals. Cows were treated 27 to 33 days postpartum (dpp) and 41 to 47 dpp, respectively. Cows in Group 2 were treated with 25 mg of Dinoprost-Trometamol three times in 14-day intervals, starting at 34 to 40 dpp. The second and third injections were administered at 48 to 54 dpp and 62 to 68 dpp, respectively. All cows were inseminated on observed estrus after a voluntary waiting period of 65 days post partum. Thus cows in Group 1 were inseminated on spontaneous estrus and cows in Group 2 on induced estrus. Cows not inseminated at 80 days post partum were palpated per rectum and treated according to a predefined protocol. Herd reproductive performance measures did not differ significantly between groups. The proportion of cows with low serum progesterone levels was significantly higher 3 days after synchronization than 24 days after synchronization (97% vs 39%). The first-service conception rate was 34.8% in Group 1 and 30.7% in Group 2 (P > 0.05). Days open were 113.5 in Group 1 and 110.9 in Group 2 (P > 0.05). It is concluded that postponing artificial insemination for one spontaneous estrus cycle after synchronization decreased the degree of synchronization. This procedure, however, had no effect on herd reproductive performance compared to insemination on first observed estrus after synchronization.

Synchronization of lactating dairy cows with prostaglandin F2 alpha: insemination on observed oestrus versus timed artificial insemination

The effect of two insemination policies after synchronization of oestrus on reproductive performance in two groups of cows was investigated. Oestrus was synchronized by two treatments with prostaglandin F2 alpha (PGF2 alpha) at a 14-day interval. Cows in Group 1 (n = 234) were inseminated twice on appointment 66 and 90 h after the second treatment. Cows in Group 2 (n = 222) were intensively watched for signs of oestrus after the synchronization protocol and inseminated on observed oestrus. Cows with abnormal discharge after synchronization were excluded from breeding and inseminated later during the study period. Service rate within 1 week after synchronization was higher in Group 1 than in Group 2 (89.3 versus 67.1%). Conception rates on first service did not differ between groups (33.2 versus 30.0%). Days to first service and days open were shorter in Group 1 (P < 0.05). The number of cows culled for infertility did not differ between the groups. Endometritis 14-20 days post-partum decreased the percentage of cows pregnant at the end of the study period in both groups but did not have a significant effect on conception rates and days open. It is concluded that additional inseminations required in the timed artificial insemination protocol were economically justified by the reduction in days open in comparison with insemination on observed oestrus after synchronization.

Serum progesterone levels in post-partum dairy cows after repeated application of the prostaglandin F2 alpha analogue D (+) cloprostenol sodium

Reproductive management programmes based on strategic use of prostaglandin F2 alpha (PGF2 alpha) to induce and synchronize oestrus in post-partum dairy cows are widespread. Repeated shortening of the oestrous cycle during early lactation in high-yielding dairy cows, however, could impair corpus luteum function and thus decrease fertility. The objective of this study was to analyse the effect of repeated treatments with the prostaglandin F2 alpha analogue D (+) cloprostenol sodium on progesterone concentrations indicative of a functional corpus luteum in post-partum dairy cows. Furthermore, the influence of milk production, parity and endometritis on progesterone concentrations under these circumstances were studied. Eighty-four cows of a commercial dairy operation were treated three to four times with D (+) cloprostenol sodium (Preloban; Hoechst Roussel Vet, Wiesbaden, Germany) at 14-day intervals, starting 22-28 days post-partum. Blood samples were collected prior to treatment 1 (sample 1) and 14 days after treatments 1, 2 and 3 (samples 2-4) and serum progesterone (P4) levels were determined. The percentage of cows with P4 levels < 1 ng/ml decreased from 51% in sample 1 to 23% in samples 3 and 4. More primiparous cows had low P4 levels 14 days after the second treatment than older cows (P < 0.05). Cows with low progesterone levels in sample 3 or 4 had lower protein contents in milk on the second milk test day post-partum and in their cumulative milk yield of the first 100 days of lactation. Clinical endometritis at post-partum examination did not influence progesterone levels after treatment with PGF2 alpha. Repeated application of PGF2 alpha (more than twice) in the post-partum period does not influence serum progesterone levels 14 days after treatment. Failure to develop luteal tissue after treatment contributed to the conception failures after first service.