9 COMPARATIVE EFFICACY OF AN 8-DAY Cue-Mate®/ESTRADIOL BENZOATE PROGRAM WITH OR WITHOUT INCLUSION OF EQUINE CHORIONIC GONADOTROPIN IN ANESTROUS DAIRY COWS

2008 ◽  
Vol 20 (1) ◽  
pp. 85 ◽  
Author(s):  
M. A. Bryan ◽  
R. Emslie ◽  
C. Heuer

The objective was to quantify and compare the reproductive response of lactating, seasonally calving dairy cows diagnosed with anovulatory anestrus (AA) to treatment with two separate progesterone (Cue-Mate�, Bioniche Animal Health, Australasia, Armidale, NSW, Australia) and oestradiol benzoate (ODB) treatment regimes, either including or excluding eCG. Cows on six commercial seasonal-calving dairy farms in New Zealand (n = 2355) were presented following 3 weeks of tailpainting and a subsequent non-observed estrus. Cows which were confirmed in anestrus with no detectable corpus luteum (CL) by rectal palpation were selected for trial inclusion (n = 1382). All cows received the standard anestrous protocol, consisting of an 8-day insertion of the progesterone device containing 1.56 g of progesterone (Cue-Mate; injection of 2 mg of ODB at the time of insertion and further injection of 1 mg of ODB 24 h after Cue-Mate removal (Day 9)). Approximately half of the cows were randomly allocated (using the RAND function within Excel, Microsoft) to a further intervention consisting of an injection of 400 IU of eCG (Pregnecol�, Bioniche) on the day of Cue-Mate removal (Day 8). This became the Treatment group with the standard treatment the Control group. Cows were then mated to detected heats; all cows not detected in estrus and inseminated were blanket-mated 36 h after the second ODB treatment. Cows were scanned ultrasonically 10 weeks post-treatment and all pregnancies were aged to the nearest half-week. Where two matings were recorded within 7 days of each other, the later mating was used. Data were analyzed using both a matched logistic regression analysis and survival analysis, using SPSS (SPSS.com) and SAS (SAS.com). Pregnecol-treated cows were more likely to conceive in the first 48 h following treatment (48.84% v. 43.10%; P = 0.06), and were more likely to be in calf within 7 days following treatment (P = 0.07). The effect of Pregnecol was greater in cows over 5 years of age, such that this stratum of cows was significantly more likely to conceive within 48 h [58.33% v. 38.10%; P = 0.00; adjusted relative risk (RR) 1.51; 95% lower confidence interval (LCI) 1.15; 95% upper confidence interval (UCI) 2.00], and was significantly more likely to be in calf within 7 days (55.20% v. 37.86%; P = 0.00; RR 1.44; LCI 1.41; UCI 1.82). Pregnecol-treated cows over 5 years of age were significantly more likely to be in calf at 4 weeks (72.22% v. 59.57%; P = 0.02; RR 1.21; LCI 1.03; UCI 1.42). Cows that had calved less than 50 days were significantly less likely to be in calf by 4 weeks (62.26% v. 69.35%; P = 0.04). In summary, the addition of a 400 IU treatment of eCG (Pregnecol) at the time of Cue-Mate removal in a standard 8-day progesterone device/ODB anestrous treatment program increased the risk of pregnancy. The effects of eCG on cows over 5 years of age were very strong and highly significant.

2012 ◽  
Vol 17 (3) ◽  
Author(s):  
Miriane Suplicy ◽  
Haroldo Suplicy Filho ◽  
Luiz Ernandes Kozicki ◽  
José Carlos dos Santos Breda ◽  
Romildo Romualdo Weiss ◽  
...  

ABSTRACT: The aim of this study was to reduce the waiting voluntary period in dairy cows by administration of two different hormonal protocols for estrus synchronization and fixed-time artificial insemination (FTAI). One hundred twenty-eight Holstein dairy cows were studied. Three groups (G) were carried out: G1 (44 treated), G2 (34 treated) and G3 (50 as control). In the treated cows the following hormonal protocols was applied between 40 and 45 days post partum: G1- Day 0 (D0) - bovine intravaginal device containing progesterone (P4) plus 1.0 mg of estradiol benzoate (EB), D8 - removal of the P4, plus 0.5 mg of cloprostenol plus 400 IU of equine chorionic gonadotropin (eCG), D9 - 1.0 mg of EB and FTAI after 36 hours. G2 - D0 - P4 intravaginal plus 50 mcg of gonadotropin-releasing hormone (GnRH), D7 - removal of the P4 plus cloprostenol plus 400 IU eCG; D9 - 50 mcg of GnRH and FTAI 16 hours after. G3 – Control group inseminated 12 hours after the visual estrus. Results: G1 and G2 were inseminated (FTAI) respectively in the D55.5 and D56.8 after calving, while the G3 in the D84.5 (p<0.01).  The pregnancy rate in the G1, G2 and G3 was respectively 47.0, 46.1 and 35.8% (p>0.05).  In Conclusion: there was significant reduction in the voluntary waiting period in treated cows and higher pregnancy rate although not significant.


2008 ◽  
Vol 20 (1) ◽  
pp. 226 ◽  
Author(s):  
D. Carballo Guerrero ◽  
A. Tribulo ◽  
R. Tribulo ◽  
H. Tribulo ◽  
G. A. Bo

Protocols that control follicular wave emergence and ovulation have had a great impact on the application of commercial on-farm embryo transfer because they permit the initiation of superstimulatory treatments at a self-appointed time. However, the most common approach for the synchronization of follicular wave emergence for superstimulation involves the use of estradiol or its esters that are not commercially available in many countries. Therefore, an experiment was designed to evaluate a protocol in which the superstimulation treatment began at the time of emergence of the first follicular wave without the use of estradiol. Bonsmara donors (29 cows and 41 heifers) were randomly allocated to one of two treatment groups. Donor animals in the experimental group (first wave group) received an intravaginal progesterone releasing device (Cue-Mate, Bioniche Animal Health, ON, Canada) along with PGF (0.150 mg D + cloprostenol, Bioprost-D, Biotay, Argentina) at random stages of the estrous cycle. Cue-Mates were removed 10.5 d later and a second PGF was administered at the same time, followed by GnRH (0.050 mg Lecirelina, Biosin-OV, Biotay, Argentina) 36 h later. Ovulation was expected to occur within 30 h after GnRH (day 0). On day 0 (36 h after gonadotropin-releasing hormone) donors received a new Cue-Mate, and superstimulation treatment was initiated with a total dose of 200 to 260 mg (heifers) or 320 mg (cows) NIH-FSH-P1of Folltropin-V in twice daily decreasing doses over 5 d. The PGF was administered with the last two Folltropin-V injections, and Cue-Mate devices were removed with the last Folltropin-V injection. All donors received 12.5 mg pLH (Lutropin-V, Bioniche Animal Health) 24 h after Cue-Mate removal and were AI 12 and 24 h later. Embryos were collected 7 d after pLH treatment. Donors in the Control group received a Cue-Mate and 2 mg of estradiol benzoate (EB; Bioestradiol, Biotay) and 50 mg of progesterone (Lab. Rio de Janeiro, Argentina), and superstimulation treatments were initiated 4 d later with the same dosages used in the first wave group. The PGF administration, Cue-Mate removal, AI, and embryo collections were done as those in the first wave group. Data were analyzed by ANOVA, and results are shown in Table 1. It was not possible to pass the cervix with the collection catheter in two heifers in the control group, and they were excluded from the analysis. There were no significant effects of donor category (cows v. heifers) or treatment on superovulatory response and embryo quality (P > 0.20). In conlusion, superstimulation on a synchronized first follicular wave is as efficacious as superstimulation following synchronization of follicle wave emergence with estradiol benzoate in Bonsmara cattle. Table 1. Superovulatory response (means ± SEM) in Bonsmara cows and heifers treated with Folltropin-V during the first follicular wave or 4 d after estradiol administration Bioniche Animal Health, Belleville, ON, Canada.


2015 ◽  
Vol 4 (1) ◽  
pp. 356-362
Author(s):  
Josemara Silva Santos ◽  
Tania Cavalcante ◽  
Francisca Elda Ferreira Dias ◽  
Domenica Palomaris Mariano de Souza ◽  
Alencariano J.S. Falcão ◽  
...  

The objective of the experiment was to evaluate the effects of recombinant bovine somatropin (rbST), and the reuse of the progesterone (P4) releasing devices in resynchronization, on the pregnancy rates of Nellore cows submitted to fixed-time artificial insemination. A group of 123 multiparae Nellore cows, was submitted to a resynchronization protocol: on day 0 a Bovine Intravaginal Device (DIB® ) with 1,0g of P4 was implanted, associated with intramuscular administration of 2,0mg of estradiol benzoate (IM); on day 8 DIB was removed; and 1,0mg of estradiol cypionate, 0,15mg of prostaglandin F2? and 300 UI of equine chorionic gonadotropin were administered; on day 10, fixed-time artificial insemination was conducted (FTAI). The cows were randomized into G1 (n=12) – without rbST / with used Bovine Intravaginal Device, G2 (n=50) – without rbST / with new DIB, G3 (n=11) - with rbST / with used DIB and G4 (n=50) – with rbST/ with new DIB. rbST was introduced on the eighth day of the protocol. Sixty days after TAI, pregnancy diagnoses were conducted, via rectal palpation. Blood samples were taken on day 0, 8 and 10 of the protocol, in order to assess P4 plasma concentrations. Pregnancy rates were statistically evaluated through Generalized Linear Models Theory and their significance was tested with Analysis of Deviance. Pregnancy rates were 58%, 40%, 81% and 48% for G1, G2, G3 and G4, respectively, with significant statistical difference for G3. Plasma concentrations of P4 were not statistically different among groups, or collections. In view of the results obtained, we concluded that the administration of rbST in association with P4 DIB, used for the third time, improves pregnancy rates. Estrus resynchronization and re-insemination positively impacted pregnancy rates.


Author(s):  
Nora Idolina Ortega Alvarez ◽  
Germán David Mendoza Martínez ◽  
Ricardo Barcena Gama ◽  
Pedro Abel Hernández García ◽  
Enrique Espinosa Ayala ◽  
...  

The objective of this study was to evaluate the economic impact of supplementing dairy cows with mixtures of polyherbal products supplying conjugates of choline (BioCholine, BC), lysine (OptiLysine, L) and methionine (OptiMethionine, M), considering the costs of veterinary treatments, the nutraceutical effects of the mixtures, the partial cost and returns of milk production. Eighty postpartum Holstein cows were randomly assigned to individually receive. The pellets no containing (Control, 20 cows) and containing polyherbal products (g/d) (BC20, 19 cows; BC40, 17 cows; BC20+L40+M20, 12 cows, and BC40+L80+M40, 12 cows) were offered to cows during the milking through automatic feeders in the course of 90 days in a commercial farm. Treatment costs were grouped in terms of antibiotics, healing, anti-inflammatories, glucogenics, hormonal, intra-mammary treatments, restorative and vitamins. Milk production was not affected (P>0.05) by polyherbal additives but there were numerical differences in the number of treatments and costs; animal health cost per cow showed a high variation coefficient (average 347%). Cows receiving BC40 and BC20+L40+M20 had reduced animal health cost per cow but only the treatment BC40 showed residual effects post experiment with an economic improvement of 2.1% over the control group, showing benefits associated to a reduction in the number of doses with antibiotics and doses of immune-stimulants. Cows receiving BC40 had the best milk yield numerically in combination with the lower number of animal health costs which resulted in the highest income.


2010 ◽  
Vol 22 (1) ◽  
pp. 179
Author(s):  
L. D. P. Sinedino ◽  
B. T. Gerhardt ◽  
A. P. Dourado ◽  
L. A. G. Nogueira

The objective of this paper was to compare 3 bovine AI protocols, evaluating the cost of each treatment and the pregnancy rates obtained, to demonstrate the importance of routine utilization of estrus synchronization techniques. The experiment was conducted in the Farm School of Cachoeiras de Macacu of the Federal Fluminense University, in the state of Rio de Janeiro, during the period from 2006 to 2007 (August to June). One hundred sixteen crossbred female Holstein-Zebu dairy cows in cycle, with body condition between 2.5 to 4 (on a scale from 1 to 5), were selected and divided randomly in 3 groups (G). Animals in G1 [n = 60; 21 heifers (H), 13 primiparous (P), and 26 multiparous (M)], with palpable corpus luteum, received 25 mg of prostaglandin F2 intravulvar, and AI was done 12 h after estrus detection. For animals in G2 (n = 30; 11 H, 6 P, and 13 M) an intravaginal progesterone device (CIDR®, Pfizer Animal Health, New York, NY, USA) was inserted and 2 mg of estradiol benzoate (EB) was administered i.m. on Day 0. On Day 8 the device was removed and 25 mg of prostaglandin was administered i.m. on Day 9, 2 mg of EB was administered, and 30 h later, timed AI of all animals was performed. For G3 (n = 26; 9 H, 5 P, and 12 M), the protocol used was similar to that for G2, except that on Day 8 400 IU of eCG was administered (in addition to the removal of the device) and on Day 9 the dose of EB was reduced to 1 mg and timed AI was done 27 h later. AI was done with semen from 2 sires with proven fertility, by the same technician. The pregnancy diagnoses were done on Day 45 by palpation per rectum and transrectal ultrasonography. The cost-benefit relation was calculated according to the cost of pharmaceuticals multiplied by the number of animals in each experimental group divided by the number of pregnancies obtained in each one, without considering the manual labor costs in all the groups and considering 3 uses of the CIDR. The statistical analyses were done using chi-square test. The pregnancy rate obtained in G2 (60%, 18/30) was superior to that in G1 (30%, 18/60) (P < 0.05), demonstrating the efficiency of the treatment that utilized progesterone. G3 (53.85%, 14/26) was similar (P > 0.05) to G2, despite the fact that the eCG was added in this group. In reference to cost-benefit, considering only the pharmaceuticals costs and the value for pregnancy obtained in each group, the costs found, respectively, were G1 U$7.02 and U$23.66; G2 U$28.57 and U$47.59; and G3 U$47.96 and U$89.05. The lowest cost in the estrus synchronization was based on the use of prostaglandins alone; the use of progesterone increased the synchronization cost, but also increased the pregnancy rate and eliminated the need for estrus observation. The addition of eCG in cows that are cycling does not necessarily demand a increase in pregnancy rate. Failure in estrus detection, using prostaglandin alone, increased the interval from calving, causing a daily loss in milk production, which justified the investment in protocols of estrus and ovulation synchronization, contributing to increase the reproductive efficiency of a dairy cow herd.


2013 ◽  
Vol 25 (1) ◽  
pp. 230
Author(s):  
G. Romero ◽  
M. Piccardi ◽  
D. Romero ◽  
G. Veneranda ◽  
G. A. Bó

The objectives of this study were to evaluate the reproductive and productive performance of dairy cows with and without puerperal metritis and to evaluate the effectiveness of using a long-acting antibiotic (200 mg mL–1 ceftiofur, Excede, Pfizer Animal Health, New York, NY, USA). Dairy cows in one dairy farm calving from July 2009 to January 2010 were examined between 3 and 14 days postpartum and classified based on vaginal discharge into 3 groups: cows with normal discharge (control); cows with purulent or red-brown vaginal discharge without foul smell, and cows with purulent or red-brown vaginal discharge with foul smell (Sheldon et al. 2006 Theriogenology 65, 1516–1530). Cows in the first 2 groups were not treated, whereas those in the third group were randomly allocated to receive 1 mL/30 kg of body weight of Excede subcutaneously behind the ear or remain untreated. From the 640 cows examined, 372 (58.2%) had normal discharge, 86 (13.4%) had a discharge without foul smell and 182 (28.4%) had a discharge with foul smell. Kaplan-Meier survival curves were obtained to compare pregnancy rates across days postpartum, and differences between curves were tested with the log rank statistic. Proportional hazards regression with PROC PHREG Cox of SAS were done to estimate the risk of pregnancy in terms of treatment, parity (first parity or ≥2 parities), type of delivery (normal or assisted), and milk production. Finally, lactation curves were modeled using SAS PROC NLMIXED to estimate the cumulative milk production at 305 days. Survival curves differed between cows in the control group and those with foul-smell discharge that were not treated (P < 0.01) and between untreated versus treated cows (P < 0.01) in the latter group. Survival curves of cows with discharge but without foul smell were intermediate and did not differ from those in the control group (P = 0.2) and those with foul smell discharge and treated (P = 0.1), but tended to be different from those with foul smell discharge and not treated (P = 0.056). The postpartum interval to achieve a 25% pregnancy rate was 72 days for cows in the control group, 73 days for cows with foul smell and treated, 83 days for cows with discharge without foul smell, and 95 days for those with foul smell and not treated. The chance of pregnancy in cows in the control group was 1.98 times higher (95% CI = 1.33, 3.08) and in cows with foul smell and treated was 2.16 times higher (95% CI = 1.37, 3.50) than those with foul smell and not treated. Finally, the chance of pregnancy in cows with discharge but without a foul smell tended to be higher (P = 0.08) than those with foul smell that were not treated, but did not differ with the other 2 groups. Parity, type of delivery, and production level did not affect pregnancy rates. Cumulative 305-day milk production was higher (P < 0.01) in control cows than those with vaginal discharge, regardless of smell and regardless of treatment. It is concluded that puerperal metritis affects the reproductive and productive performance of dairy cows, and the treatment with Excede was effective in reducing the adverse effects on reproductive performance.


2010 ◽  
Vol 22 (1) ◽  
pp. 358 ◽  
Author(s):  
D. Carballo Guerrero ◽  
A. Tríbulo ◽  
R. Tríbulo ◽  
H. Tríbulo ◽  
G. A. Bó

Although we have previously shown that ovarian superstimulation during the first follicular wave resulted in a successful response (Carballo Guerrero D et al. 2009 Reprod. Fertil. 21, 242), the current protocol needs to be optimized in order to be used in the field. Therefore, an experiment was designed to simplify this treatment and to compare it with the traditional superstimulation protocol using progesterone and estradiol. Simmental cows (n = 14) were subjected to 3 superstimulation treatments (2 first wave groups and 1 control group) in a crossover design (i.e. all cows received the 3 treatments and all treatments were represented on each collection day). Cows in Group 1 received a progesterone-releasing device (Cue-Mate®, Bioniche Animal Health, Belleville, Ontario, Canada) along with 0.150 mg of D + cloprostenol (PGF; Bioprost-D®, Biotay, Buenos Aires, Argentina) at random stages of the estrous cycle. A second PGF was injected 5 days after Cue-Mate® insertion, followed by GnRH (0.050 mg of lecirelin; Biosin-OV®, Biotay) 36 h later (i.e. 7 days after Cue-Mate® insertion). Based on previous studies, ovulation was expected to occur 30 to 36 h later. Therefore, superstimulation treatments were initiated 36 h after GnRH (Day 0), with a total dose of 400 mg NIH-FSH-P1 of Folltropin®-V (Bioniche Animal Health) in twice-daily decreasing doses over 4 days. Prostaglandin was administered with the last 2 Folltropin®-V injections and Cue-Mate® devices were removed with the last Folltropin®-V injection. Cows received 12.5 mg of porcine LH (Lutropin®-V, Bioniche Animal Health) 24 h after Cue-Mate® removal and were AI 12 and 24 h later. Ova/embryos were collected 7 days after porcine LH and evaluated following IETS recommendations. Cows in Group 2 were treated similarly to those in the Group 1, except they did not receive the second PGF injection 5 days after Cue-Mate® insertion (thus eliminating the need to handle animals on that day). Finally, cows in Group 3 [estradiol benzoate (EB)+P4 control group] received a Cue-Mate® plus 2.5 mg of EB (Bioestradiol®, Biotay) and 50 mg of progesterone (P4; Lab., Rio de Janeiro, Argentina) at random stages of their estrous cycle. Superstimulation treatments were initiated 4 days later (Day 0) following the same protocol used in Group 1. Data were transformed to square root and analyzed by ANOVA. Mean (± SEM) numbers of ova/embryos collected, fertilized ova, and transferable embryos did not differ among groups (12.9 ± 2.0, 9.8 ± 1.7, and 6.6 ± 1.2; 11.5 ± 1.7, 9.3 ± 1.5, and 7.7 ± 1.6; and 14.5 ± 2.8, 9.4 ± 2.3, and 6.8 ± 1.7 for Groups 1, 2, and 3, respectively). In conclusion, data demonstrated that superstimulation during the first follicular wave can be successfully used in groups of randomly cycling donors without the need for estrus detection or estradiol to synchronize follicular wave emergence. The protocol is easy to follow and embryo production is comparable to that of the estradiol and progesterone protocol.


2004 ◽  
Vol 16 (2) ◽  
pp. 127 ◽  
Author(s):  
G.A Bo ◽  
L. Cutaia ◽  
P. Chesta ◽  
D. Moreno

Treatments with progesterone (P4) releasing devices and estradiol benzoate (EB) have been extensively used in fixed-time AI (FTAI) programs in beef cattle. However, pregnancy rates in postpartum cows kept on pasture often have been lower than expected because of poor body condition score (BCS) and a high incidence of anestrous. A recent study (Cutaia L et al., 2003 Theriogenology 59, 216) suggested that the addition of eCG to a P4/EB FTAI program may improve pregnancy rates in cows with fair to poor BCS, but results were not conclusive. Therefore, this experiment was designed to further investigate the effect of eCG treatment on pregnancy rates in postpartum beef cows in those conditions. The experiment was performed at 2 locations with lactating Angus cows (n=93), 60 to 90d postpartum with a BCS 1.9 (1 to 5 scale; Location 1), and crossbred Zebu cows (n=290), 60 to 90d postpartum with a BCS 2.0 (Location 2). In each Location, cows were randomly allocated to 1 of the following treatment groups: Control, eCG Day6, or eCG Day8. All cows received a P4 intravaginal device (DIB, Syntex, Argentina) and 2mg EB i.m. (Syntex) on Day0, 500mg cloprostenol (Estroplan, Syntex) at the time of DIB removal (Day8), 1mg EB i.m. on Day9 and FTAI 52 to 56h after DIB removal. Cows in the Control group received no further treatment, whereas cows in the eCG-treated groups received 400 IU eCG (Novormon 5000, Syntex) on Day6 or Day8. Cows were examined on Day0 by rectal palpation (Location 1) or by ultrasonography (US; Location 2) and were classified as those with a CL or without a CL, with either large (&gt;8mm) or small (&lt;8mm)small follicles. Pregnancy was determined by US 45d after FTAI. Data were analyzed by logistic regression and the effects of location, treatment, ovarian status, AI technician and semen were considered in the model. There was no effect of location (P=0.3), AI technician (P=0.2) or semen (P=0.8) on pregnancy rates. However, there was an effect of treatment (P=0.02), attributed to higher pregnancy rates in the eCG Groups than in the Control Group (Table). Furthermore, cows with a CL or without a CL but with large follicles on Day 0 had higher pregnancy rates than those with small follicles (P=0.04). It was concluded that the use of eCG in a P4/EB FTAI program improved pregnancy rates in postpartum beef cows that were in fair topoor BCS.


2020 ◽  
Vol 76 (03) ◽  
pp. 6364-2020
Author(s):  
KUDRET YENİLMEZ ◽  
NURULLAH ÖZDEMİR

The aim of this study was to determine the effect of equine chorionic gonadotropin (eCG) applied in postpartum (pp) period on ovarian follicle development, serum estradiol concentration, serum progesterone concentration, the calving-to-first oestrus (calving-to-first insemination) interval, and conception at first insemination. The material of this study consisted of 20 cows on day 14 pp. Cows included in this study were randomly divided into two groups. Cows in the first group, were treated with eCG (500 IU Folligon; Intervet, Holland) for 14 days. No treatment was applied to the second group, and it was left as a control group, Ovarian follicle diameters were measured by ultrasonographic examination on days 14, 16, 18, 20 and 22 pp in all animals included in the study. Serum estradiol and progesterone were from blood samples taken on the same days. All animals included in the study were followed up until the first observable oestrus was detected, and they were inseminated 12 hours after the appearance of oestrus symptoms. A pregnancy examination was performed on the 45th day after insemination. In cows administered with eCG during postpartum period, an increase in ovarian follicle diameters compared to untreated cows and a decrease in the calving-to-first oestrus interval were determined. In contrast, serum estradiol and progesterone hormone levels did not differ between the two groups. Pregnancy rate in the experimental group was higher than that in the control group, but there was no statistical difference between them. As a result, it was concluded that eCG applied to dairy cows on day 14 pp did not affect serum estradiol and progesterone levels, but it affected the ovarian follicle diameter and the calving-to-first oestrus interval positively.


2006 ◽  
Vol 18 (2) ◽  
pp. 225
Author(s):  
U. H. Kim ◽  
G. H. Suh ◽  
I. H. Kim

Treatment with estradiol benzoate (EB), compared to GnRH, in a controlled internal drug release (CIDR)-based timed AI protocol induced relatively asynchronous follicular wave emergence, resulting in ovulation of smaller ovulating follicles (Kim et al. 2005 Theriogenology 63, 260-268). In this study, we compared new follicular wave emergence and development following treatment with EB (2 mg) plus progesterone (50 mg) at a growing (Day 3 after ovulation) or a static (Day 8) phase of the dominant follicle during the first follicular wave in CIDR-treated, lactating dairy cows. Previously synchronized, lactating dairy cows received CIDRs (InterAg, Hamilton, New Zealand; Day 0) 3 days after ovulation and were assigned to two treatment groups and a control group. Cows in the T1 group (n = 11) received 2 mg EB (SY Esrone; Samyang, Seoul, Korea) and 50 mg P4 (SY Ovaron; Samyang) i.m., and those in the control group (n = 10) received no treatment at that time. Other previously synchronized cows received a CIDR (Day 0) with injections of 2 mg EB plus 50 mg P4 i.m. 8 days after ovulation (T2 group, n = 10). Thereafter, all cows received PGF2� (Lutalyse; Pharmacia & Upjohn, Puurs, Belgium) at the time of CIDR removal on Day 7, and GnRH (Conceral; Dongbang Co., Seoul, Korea) on Day 9. Ovaries of each cow were examined by transrectal ultrasonography (Sonoace 600 with 7.5 MHz linear-array transducer; Medison Co., Ltd, Seoul, Korea) every 24 h from Days 0 to 9, on Day 11, and on Day 14 of treatment to observe changes in ovarian structures (follicles and corpora lutea (CL)). Data were analyzed by Fisher's exact test, Kruskal-Wallis test, and ANOVA using an SAS program (SAS Institute, Inc., Cary, NC, USA). Follicular wave emergence occurred within 7 days in 3/10 of the control group, 9/11 of the T1 group, and 9/10 of the T2 group (P < 0.05). The interval to wave emergence did not differ (P > 0.05) among groups (3.7 � 1.2, 4.8 � 0.5, 5.9 � 0.3 days, respectively). While the diameters of dominant follicles on Day 0 were greater (P < 0.01) in the T2 group (14.3 � 1.2 mm) than in the control (9.4 � 0.6 mm) and T1 (10.5 � 0.7 mm) group, diameters of preovulatory follicles on Day 9 were significantly smaller (P < 0.01) in the T1 (13.6 � 0.7 mm) and T2 (12.3 � 0.5 mm) groups than in the control group (16.4 � 0.8 mm). Synchronized ovulation by 40 h after the GnRH injection (Day 11) occurred in 10/10 of the control group, 10/11 of the T1 group, and 9/10 of the T2 group (P > 0.05). In conclusion, administration of 2 mg EB plus 50 mg P4 at both a growing and a static phase of the dominant follicle during the first follicular wave results in synchronous follicular wave emergence and development and also synchronized ovulation in CIDR-treated, lactating dairy cows.


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