Estrus Synchronization Protocol Research Articles

Efficacy of various five-day estrous synchronization protocols in sheep

The objective of this study was to determine the effects of ewe estrus synchronization protocols including combinations of controlled internal drug releasing (CIDR) inserts for 5 d, GnRH, and PG on concentrations of progesterone (P4) and reproductive performance of ewes during different breeding seasons. Experiment 1 was conducted during the transition season (August–October) and Experiment 2 was conducted during the anestrous season (April–May). In both experiments ewes received 1 of 4 treatments: (1) untreated (CON); (2) CIDR (0.3g P4) insert (CT); (3) CIDR and PG at CIDR removal (CTP); or (4) GnRH at CIDR insertion and PG at CIDR removal (CTG). Rams equipped with marking harnesses were introduced at CIDR removal (d 0) and ewes were observed for breeding marks twice daily at 0800h and 1700h. In Experiment 1, days to estrus was greater (P≤0.01) in CON (9.5±1.10 d) and CTP (6.5±1.04 d) compared with CT (3.6±1.03 d). No differences (P=0.27) were detected in pregnancy rate within the first 17 d of the breeding season for CON, CT, CTP, and CTG treatments (37±7.8%, 62±7.5%, 56±8.1%, and 46±7.7%, respectively). Similarly, no differences (P≥0.28) were detected among treatments for lambing rate and prolificacy. Contrasts for all CIDR treatments compared to controls determined that CIDR treated ewes had less days to estrus and lambing (P≤0.05) than control ewes. In Experiment 2, days to estrus was greater (P≤0.02) in CON (6.5±1.05 d) and CTP (5.9±0.88 d) compared with CTG (3.0±0.88 d). No differences were detected (P≥0.23) among treatments for overall percentage of ewes exhibiting estrus. No differences (P=0.79) in pregnancy rate within the first 17 d of the breeding season were detected among treatments (42±12.4%, 37±11.3%, 35±11.1%, and 50±10.9% for CON, CT, CTP, and CTG, respectively). No differences (P≥0.44) were observed among treatments in overall lambing rate and prolificacy. In conclusion, inserting a CIDR for 5 d prior to ram introduction regardless of the use of PG or GnRH, reduced the interval to estrus compared with untreated ewes but did not impact overall pregnancy rates, lambing rates, or prolificacy.

Conception Rate and Frequency of Single and Multiple Births in Estrus Synchronized Nari Suwarna Ewes Maintained Under Two Different Systems of Feeding Strategies

The purpose of this study was to investigate the conception rate and frequency of single and multiple births in estrus synchronized NARI Suwarna ewes maintained under two different systems of feeding strategies. Fifty adult ewes of same age were randomly divided into two groups as per the type of feeding management. Ewes in both the groups were subjected for estrus synchronization protocol for 12 days by using intravaginal progesterone sponges with PGF2α and PMSG. Ewes were inseminated with freshly collected & diluted semen and pregnancy was diagnosed with the aid of ultrasonograpy 30 days of post AI. The mean conception rate recorded was 83.3 & 55% for scientific feeding and pastures grazing respectively. Similarly, single & multiple births recorded were 20% & 80% and 45.45% & 54.55% for scientific feeding and pasture grazing respectively. In conclusion, significantly higher (83.3%) conception rate and multiple births (80%) were observed in ewes maintained under scientific system of feeding than pasture grazed ewes.

Comparison between the reproductive performance of ewe hoggets and mature ewes following a progesterone-based oestrus synchronization protocol

Two experiments were conducted to compare the reproductive performance of ewe hoggets and mature ewes. All ewes were synchronized by an intravaginal progesterone-releasing device and bred together over a 5-day period. In Experiment 1, of those joined with the ram, more mature ewes ovulated (99% vs 68%; P < 0.05) with a higher ovulation rate (1.82 vs 1.14; P < 0.05) than ewe hoggets. Mature ewes had a higher pregnancy rate (98% vs 47%; P < 0.05) and lower early pregnancy loss (13% vs 41%; P < 0.05) than ewe hoggets. In Experiment 2, the ovulation rate (1.84 vs 1.44; P < 0.05) and pregnancy rate (86% vs 7%; P < 0.05) was higher in mature ewes compared with ewe hoggets. Combined, these studies help to quantify the difference in reproductive performance during breeding and pregnancy between ewe hoggets and mature ewes, and help to direct further research.

OVARIAN RESPONSE OF DAIRY COWS TO PROGESTERONE COMBINED ON

The objective of this study was to evaluate the response of ovaries in estrus synchronizationprotocol using GnRH-PGF2α based protocol combined progestin in a herd with tie-stall housing system.A total of 20 Holstein Friesian cows at different stages of estrus cycle in a dairy herd were enrolled inthe present study. The cows were randomly allocated into two treatment groups; with and without CIDR(Controlled internal drug release) insertion. All cows received 100 μg of GnRH I.M. at the beginning ofthe treatment (d 0) without regard to the stages of the estrus cycle followed by 25 mg PGF2α IM 7dayslater. Cows in CIDR group were inserted CIDR into the vagina at the time of GnRH administration andwere removed on the day of PGF2α administration. estrus signs were checked twice daily starting onday-2 after initiation of the protocol, except cows in CIDR group the estrus signs were checked startingon day-8 of the protocol. The animals showing estrus signs were noted. Blood samples were collectedfrom all animals on the days of GnRH and PGF2α treatments and on day-10 after initiation of protocolfor progesterone concentration. The results of this study showed that 30% animals in cows withoutCIDR insertion showed estrus signs prior to PGF2α injection. Involving CIDR to synchronized estruswith GnRH-PGF2α based protocol avoided the occurrence of premature estrus and maintained highprogesterone concentration on the day of PGF2α administration. It is concluded that ovarian responseafter involving CIDR in the protocol for estrus synchronization especially using combination of GnRHand PGF2α were much effective to synchronize the initiation of estrus in dairy cows. Likewise, the useof progesterone avoided premature estrus.

Comparação entre protocolos de sincronização de cio para receptoras de embriões bovinos

O trabalho foi conduzido com objetivo de avaliar dois protocolos de sincronização de cio em receptoras de embriões sobre a taxa de aproveitamento ao longo do ano, bem como os custos e as características reprodutivas dos animais sincronizados. Os tratamentos foram: T1: sincronização para transferência em tempo fixo com utilização de implantes de progesterona e estradiol, e T2: sincronização com aplicação de prostaglandina e observação de cio. Foram sincronizadas 2947 receptoras de embriões, e a taxa de aproveitamento foi de 83,24% no tratamento 1, e 60,73% no tratamento 2. Os corpos lúteos foram avaliados no dia da inovulação de embriões, obtendo-se 63,73% da ovulação no ovário direito. As taxas de aproveitamento não apresentaram diferenças entre os meses do ano (P&gt;0,05). O protocolo em tempo fixo apresentou custo mais elevado (US$ 10,51 vs 2,03) que a utilização de prostaglandinas e observação de cio, no entanto a taxa de aproveitamento de receptoras foi maior. As taxas de aproveitamento das receptoras não variam ao longo do ano, quando atendidas as condições de nutrição e manejo adequados para receptoras de embrião bovino.

Efficacy of four synchronization protocols on the estrus behavior and conception in native Korean cattle (Hanwoo)

Ineffective estrus detection is the foremost limiting factor in the fertility of farmed cattle worldwide. Failure to detect estrus or erroneous diagnosis of estrus results in great economic losses in Korea each year. This study was carried out in order to comprehensively describe the estrus behaviors and conception rates of different estrus synchronization protocols applied to 40 cycling native Korean cattle (Hanwoo). The cows were grouped into four (n = 10) and treated with the following protocols: (1) Day -15: controlled intravaginal drug-releasing device (CIDR) for 12 days; Day -5: prostaglandin F2α (PGF2α), (2) ovulation synchronization (OVS): Day -15: GnRH; Day -6: PGF2α; Day -4: GnRH, (3) Day -15: progesterone-releasing intravaginal device for 12 days; Day -5: PGF2α; and (4) Day -15: PGF2α; Day -4: PGF2α. Artificial insemination was performed 12 hours after the detection of estrus using frozen-thawed semen. Estrus signs were compared using a charge-coupled device camera (CCDC) and a control method (direct visual observation). The pregnancy of the cows was determined by transrectal ultrasonography at Days 25 to 30 postinsemination. The results indicated that the day of estrus return was significantly earlier using the CCDC method compared with direct visualization (P < 0.05). Mounting of other cows was the most predominant sign of estrus among the flock (P < 0.05), as analyzed using the CCDC. In the OVS group, a lower rate of mounting was observed than in the other three groups. Moreover, significantly fewer estrus behaviors were noticed in the OVS protocol group (P < 0.05). Both first service conception and overall conception rates were significantly higher (P < 0.05) in the CIDR and OVS treatment groups. In conclusion, the CIDR and OVS protocols appear to be the best practice for the synchronization of estrus for reproductive competence through the CCDC in Hanwoo cows. However, CIDR has a practical advantage over OVS with respect to estrus detection.

Effect of gonadotropin-releasing hormone in long-term controlled internal drug-release protocols on pregnancy rates in beef heifers artificially inseminated after observed estrus or fixed time

<h2>ABSTRACT</h2> Beef heifers at 4 ranches were assigned to 1 of 2 estrus synchronization protocols: CIDR Select heifers received a controlled internal drug-release device (CIDR) on d 0, which was removed on d 14, gonadotropin-releasing hormone (GnRH) on d 23, and prostaglandin (PG) F_2α on d 30; and CIDR-PG heifers received CIDR on d 0, which was removed on d 14, and PG on d 30. At 3 ranches (n = 264, Exp. 1), heifers were observed for estrus and AI 12h after exhibition of estrus (EAI) or were fixed-time AI (TAI) with GnRH at 72h. Heifers at the fourth ranch (n = 320, Exp. 2) were fitted with estrus-detection patches at PG administration, which were scored 72h later at TAI. In Exp. 1, the percentage of heifers observed in estrus, the interval to observed estrus, variance for the interval to estrus, and the distribution of observed estrus did not differ (P > 0.52) between treatments. Pregnancy rate to EAI did not differ (P = 0.18) between treatments (71% for CIDR Select and 59% for CIDR-PG). There was a treatment × ranch interaction (P = 0.01) for TAI pregnancy rate. Pregnancy rate to EAI was greater (P = 0.003) than pregnancy rate to TAI (64 vs. 45%). In Exp. 2, estrus-detection patches on heifers synchronized with CIDR Select tended (P = 0.08) to have less wear than patches on heifers synchronized with CIDR-PG. Fixed-time AI pregnancy rate in Exp. 2 did not differ (P > 0.67) between treatments, averaging 50%. Timed-AI pregnancy rate was greater (P = 0.05) for heifers with estrus-detection patches that were 50 or 100% color change than for heifers with patches that had no color change. Inclusion of GnRH in long-term CIDR protocols did not improve synchrony of estrus or AI pregnancy rates.

Comparison of long-term controlled internal drug release-based protocols to synchronize estrus and ovulation in postpartum beef cows1

Two experiments were conducted to examine the necessity of adding a GnRH injection to a 14-d controlled internal drug release (CIDR)-based protocol for synchronization of estrus and ovulation in postpartum beef cows. The experiments were designed to characterize long-term CIDR-based protocols in cyclic and noncyclic postpartum beef cows on the basis of estrous response, follicular dynamics, and serum steroid hormone concentrations. In Exp. 1 and 2, crossbred lactating beef cows (n = 40 and 38, respectively) were randomly assigned to 1 of 2 treatments by age, days postpartum (DPP), BCS, and estrous cyclicity status: 1) cows received a CIDR from d 0 to 14 followed by GnRH 9 d after CIDR removal (d 23) and PGF2α on d 30 (CIDR Select) or 2) CIDR administration from d 0 to 14 followed by PGF2α 16 d later (d 30; Show-Me-Synch). Estrus detection was performed using HeatWatch transmitters applied from CIDR removal to AI. Cows in Exp. 1 were artificially inseminated based on detected estrus whereas cows in Exp. 2 were inseminated at a fixed time. In both experiments, follicle turnover on d 25 of treatment was greater among CIDR Select-treated cows (P < 0.001) compared with Show-Me-Synch-treated cows. In Exp. 1, CIDR Select-treated cows tended to have a reduced (P = 0.06) variance for the interval to estrus after PGF2α than Show-Me-Synch-treated cows. Also, cows assigned to the CIDR Select protocol had greater concentrations of progesterone (P < 0.05) on the day before PGF2α administration as well as greater concentrations of estradiol-17β (P < 0.01) 48 h after PGF2α administration. In Exp. 2, mean dominant follicle diameter on d 23 and at fixed-time AI (FTAI) did not differ between treatments (P > 0.10), but Show-Me-Synch-treated cows had larger follicles at d 28 (P < 0.001) and tended to have larger follicles at PGF2α (d 30; P = 0.06) compared with cows assigned to CIDR Select. In summary, the administration of GnRH on d 23 of a long-term CIDR-based estrus synchronization protocol increased follicle turnover; however, both long-term CIDR-based protocols yielded similar physiological outcomes among estrous-cycling and anestrous postpartum beef cows.

Different influence of ovine estrus synchronization treatments on caruncular early angiogenesis.

The present study compares two protocols for ovine estrus synchronization by assessing the caruncular angiogenic response to the establishment of pregnancy. The analysis consisted of the immunohistochemical evaluation of Vascular Endothelial Growth Factor (VEGF), Platelet Endothelial Cell Adhesion Molecule-1 (PECAM-1, CD31) and Von Willebrand Factor (vWF) in ovine caruncular stroma. A flock of thirty-eight adult ewes was divided in two groups and synchronized with either progestagens (Group P) or prostaglandin analogues (Group PG). Immunohistochemistry was performed in uterine samples obtained from pregnant ewes (P, n=15; PG, n=13) on days 15 post coitus (pc), 17pc and 21pc (day 0 =day of estrus). Each factor was assessed by total vascular density (TVD, total positive blood vessels/mm2), capillary vascular density (CVD, positive blood capillaries/mm2) and arteriolar vascular density (AVD, positive arterioles/mm2). Group P demonstrated higher VEGF-CVD (P=0.045) when compared to prostaglandin treated animals. Vascular CD31-expression decreased on days 15pc and 21pc (TVD, P=0.007 and CVD, P=0.014) in both groups. vWF analysis did not show significant differences between groups or days of study. These results demonstrate a different influence of progestagen-based and prostaglandin analogues-based synchronization treatments over VEGF vascular expression during caruncular development taking place in response to pregnancy establishment. In addition, observations pointed out in this study support the involvement of CD31 in the angiogenic stimulus that occurs during early maternal placentation in the ewe.

Ovarian response and pregnancy rates to timed artificial insemination in beef heifers after synchronization of follicular waves and ovulation via a 14-day controlled internal drug-release insert estrus synchronization protocol

ABSTRACT The effects of extended progestin exposure, gonadotropin-releasing hormone (GnRH) versus prostaglandin (PG) F 2α at controlled internal drug-release (CIDR) insertion, and GnRH on d 7 versus 9 of a 14-d CIDR on ovarian response and timed AI (TAI) pregnancy rate were evaluated. In Exp. 1 beef heifers (n = 319) received 1) GnRH and CIDR on d 0, GnRH on d 9, and 50 mg of PG on d 14 at CIDR removal (14-d GnRH-9); 2) 14-d GnRH-9 but with PG versus GnRH on d 0 (14-d PG GnRH-9); or 3) GnRH and CIDR on d 9 and 25 mg of PG at CIDR removal on d 14 (5-d CO-Synch+CIDR). Heifers (n = 452) in Exp. 2 received 1) 14-d GnRH-9, 2) 14-d GnRH-9 with GnRH on d 7 versus 9 and 25 versus 50 mg of PG on d 14 (14-d GnRH-7), or 3) GnRH and CIDR on d 7 and 25 mg of PG at CIDR removal on d 14 (7-d CO-Synch+CIDR). All heifers received GnRH at TAI. Pregnancy rate was not different (P ≥ 0.66) among treatments in either experiment. In Exp. 1, heifers in d 6 to 10 of the estrous cycle at protocol initiation had a greater (P 0.10) from d 0 to 5. Results indicate extended progestin exposure, PG at CIDR insertion, and GnRH timing did not affect pregnancy rate to TAI.

Administration of a GnRH analog on day 9 of a 14-day controlled internal drug release insert with timed artificial insemination in lactating beef cows1

Many estrus synchronization protocols aim to induce a new follicular wave to improve response and enhance pregnancy rate. Our objectives were to determine the effectiveness of GnRH analog administered d 0 and 9 during an extended controlled internal drug release (CIDR) protocol to produce 2 follicular waves, induce cyclicity in anestrus cows, and evaluate the efficacy of a single 50-mg dose of PGF2α to initiate luteal regression on CIDR removal. Lactating beef cows (n = 779) at 3 locations (n = 247, location 1; n = 395, location 2; n = 137, location 3) were randomly assigned to 1 of 3 treatments. Cows in the 14-d 50 PG treatment received a CIDR (1.38 g progesterone) with 100 μg GnRH analog intramuscularly (i.m.) on d 0, 100 μg GnRH analog i.m. on d 9, and CIDR removal concurrent with 50 mg PGF2α i.m. on d 14. Cows in the 14-d 6-h PG treatment were assigned the same protocol as the 14-d 50 PG treatment except that 25 mg PGF2α i.m. was given on d 14 plus 25 mg PGF2α i.m. 6 ± 1 h later. Cows in the control treatment, 5-d CO-Synch + CIDR (5-d CO-Synch), received a CIDR concurrent with 100 μg GnRH analog i.m. on d 9, CIDR removal concurrent with 25 mg PGF2α i.m. on d 14, and 25 mg PGF2α i.m. 6 ± 1 h after first F2α injection. Cows in all treatments received 100 μg GnRH analog i.m. and timed AI (TAI) 72 ± 3 h after CIDR removal. Pregnancy status to TAI was determined by ultrasonography 37 to 40 d after TAI. Averaged over all locations, pregnancy rates to TAI for 14-d 50 PG, 14-d 6-h PG, and 5-d CO-Synch treatments were 58.2%, 46.8%, and 41.9%, respectively. Pregnancy rates to TAI were greater (P < 0.05) in 14-d 50 PG treatment than 14-d 6-h PGF2α and 5-d CO-Synch treatments. Cycling status at 2 locations (n = 243, location 1; n = 391, location 2) was determined from blood collected on d -7 and 0; cows with serum progesterone concentrations >1 ng/mL at either (or both) bleeding date were considered cyclic. Averaged over the 2 locations, there was a tendency (P = 0.06) for a greater number of cyclic animals to become pregnant to TAI in the 14-d 50 PG treatment (64.4%) than 5-d CO-Synch treatment (50.2%). The 14-d CIDR with GnRH analog on d 0 and 9 and a single 50-mg dose of PG i.m. at CIDR removal was a more efficacious protocol to maximize TAI pregnancy rates than the standard 5-d CO-Synch.

Effects of ram presence during synchronization period and previous experience on certain estrus parameters and sexual behaviors in Kıvırcık ewes

This study aimed to investigate the effects of ram presence during estrus synchronization protocol and previous sexual experience on estrus onset, estrus duration, and sexual behaviors in Kıvırcık ewes. The ewes were divided into 2 groups according to the presence or absence of rams during the synchronization protocol. Ewes in each group were also divided into 3 subgroups according to their previous sexual experience. Ram presence during synchronization protocol did not affect estrus onset, estrus duration, mean attractivity, mean proceptivity, and mean receptivity. Nonexperienced ewes had longer estrus onset and shorter estrus duration than experienced ewes. Experienced ewes were more attractive and more receptive than the naive ones. It is concluded that although ram presence during estrus synchronization has no effect on sexual behaviors, previous sexual experience with males improves the expression of sexual behaviors in Kıvırcık ewes. Therefore, detection of estrus in maiden ewes should be performed more carefully in order to get high rates of flock fertility.

The effect of maternal–fetal attachment education on maternal mental health

This study aimed to investigate the effects of ram presence during estrus synchronization protocol and previous sexual experience on estrus onset, estrus duration, and sexual behaviors in Kivircik ewes. The ewes were divided into 2 groups according to the presence or absence of rams during the synchronization protocol. Ewes in each group were also divided into 3 subgroups according to their previous sexual experience. Ram presence during synchronization protocol did not affect estrus onset, estrus duration, mean attractivity, mean proceptivity, and mean receptivity. Nonexperienced ewes had longer estrus onset and shorter estrus duration than experienced ewes. Experienced ewes were more attractive and more receptive than the naive ones. It is concluded that although ram presence during estrus synchronization has no effect on sexual behaviors, previous sexual experience with males improves the expression of sexual behaviors in Kivircik ewes. Therefore, detection of estrus in maiden ewes should be performed more carefully in order to get high rates of flock fertility.

Use of Two Estrus Synchronization Protocols and Their Success on Pregnancy in Zebu and Crossbred Heifers at Char Areas of Bangladesh

Use of Two Estrus Synchronization Protocols and Their Success on Pregnancy in Zebu and Crossbred Heifers at Char Areas of Bangladesh

Effect of 2, 4, and 5-hour intervals between 2 prostaglandin F2α injections administered with 5-day CO-Synch + CIDR protocol on pregnancy rate in beef cows

<h2>ABSTRACT</h2> The objective of this study was to compare fixed-time AI (TAI) pregnancy rates resulting from intervals of 2, 4, or 6 h between 2 prostaglandin (PG) F_2αinjections administered in a 5-d CO-Synch + controlled internal drug-release device (CIDR) estrus synchronization protocol. Angus and Angus-crossbred cows (n = 901) maintained on native pasture at 3 locations were randomly assigned to treatments after blocking for BCS and postpartum interval. All cows received gonadotropin-releasing hormone and a CIDR insert on d –5, PG and CIDR removal on d 0, and gonadotropin-releasing hormone with TAI at 72 h. Cows also received a second injection of PG either2, 4, or 6 h after the first injection of PG. Pregnancy rates were determined by transrectal ultrasonography 40 ± 2 d following TAI. Body condition score and postpartum interval did not differ (P > 0.72) between estrus synchronization protocols, averaging 4.3 and 81 d, respectively. Fixed-time AI pregnancy rate was least (P ≤ 0.05) in cows receiving 2 PG injections separated by 2- and 4-h intervals (average 51%) compared with cows receiving 2 PG injections separated by a 6-h interval (59.7%). Reducing the interval between PG injections from 6 to 2 h resulted in a 9-percentage-point (15%) reduction in TAI pregnancy rates for cows synchronized with a 5-d COSynch + CIDR protocol.

Therapy of ovarian inactivity in postpartum Bulgarian Murrah buffaloes by PRID and Ovsynch estrus synchronization protocols

The aim of the present study was to assess therapeutical effect of modified Ovsynch and PRID estrus synchronization protocols in Bulgarian Murrah buffalo with inactive ovaries during the low-breeding season. The study was carried out in 46 Bulgarian Murrah buffaloes with small inactive ovaries established by two consecutive transrectal ultrasonographies on Day 40 and 50 postpartum. At the start of the therapy the buffaloes were randomly divided into three groups. Group I ( n =18) was treated by PRID-based protocol; Group II ( n =18) was treated by Ovsynch based protocol and Group III (control; n =10) was injected intramuscular with saline at the same days as in the first two groups and fertile bull was introduced after that. The animals in the different groups were submitted to ultrasound examination at day of artificial insemination or bull introduction. Ovulation was determined 7 days post insemination by ultrasound. The pregnancy diagnosis was done 30 days after insemination. Mean diameter of the largest follicles at the start of therapy and the day of AI was registered. In the hormonal treated buffaloes estrus clinical sings, ovulation rate and pregnancy rate after AI were determined. In the control group pregnancy rate after spontaneous estrus was established. The mean diameter of the largest follicles determined on Days 40 and 50 after calving was not over 9 mm for all buffaloes. At day of AI the average diameters of the preo-vulatory follicles in PRID and Ovsynch treated buffaloes were significantly ( P <0.01) greater than these on Day 0. The cases of a clear uterine mucus discharge during the induced estrus were significant more ( P <0.05) for Group I (94.4%) than Group II (66.7%). The pregnancy rate after AI (56.6% and 38.8%) in PRID and Ovsynch program was significant higher ( P <0.05) than pregnancy rate after spontaneous estrus (10%) in the control group. the treatment of buffalo ovarian inactivity could start on Day 50 postpartum. The PRID and Ovsynch estrus synchronization protocols by substitution of the second GnRH with hCG, could be successfully used for therapy of Bulgarian Murrah buffaloes with inactive ovaries during the low-breeding season.

Effects of vaccination against reproductive diseases on reproductive performance of beef cows submitted to fixed-timed AI in Brazilian cow-calf operations

The objectives were to assess incidence of pregnancy losses, associate this outcome with immunization programs against reproductive diseases, and evaluate the effects of vaccination against bovine herpesvirus-1 (BoHV-1), bovine viral diarrhea virus (BVDV), and Leptospira spp., on reproductive efficiency of Brazilian cow-calf operations. In experiment 1, 7614 lactating Nelore cows from 18 ranches were assigned to the same estrus synchronization and fixed-time AI protocol (ESFTAI; Days −11 to 0). Pregnancy status was determined with transrectal ultrasonography on Days 30 and 120 after AI. Pregnancy loss was deemed to have occurred when cows were pregnant on Day 30 but nonpregnant on Day 120. Incidence of pregnancy loss across all ranches was 4.1%; pregnancy losses were detected (P < 0.10) in 14 ranches but not detected (P > 0.11) in four ranches. Pregnancy loss was lower (P ≤ 0.02) in ranches that vaccinated against BoHV-1, BVDV, and Leptospira spp. compared with ranches that did not vaccinate, or only vaccinated against Leptospira spp. In experiments 2 and 3, lactating Nelore cows (N = 1950 and 2793, respectively) from ranches that did not have a history of vaccinating against reproductive diseases (experiment 2), or only vaccinated against Leptospira spp. (experiment 3), were assigned to the same ESFTAI used in experiment 1. Within each ranch, cows received (VAC) or not (CON) vaccination against BoHV-1, BVDV, and Leptospira spp. at the beginning of the ESFTAI (Day −11) and 30 days after (Day 41) AI. In experiment 2, VAC cows had greater (P ≤ 0.05) pregnancy rates compared with CON on Days 30 and 120. In experiments 2 and 3, pregnancy loss was reduced (P ≤ 0.03) in primiparous VAC cows compared with CON cohorts. In experiment 4, 367 primiparous, lactating Nelore cows previously vaccinated against Leptospira spp. were assigned to the same ESFTAI used in experiment 1. Cows received VAC, or the same vaccine 30 days before (Day −41) and at the beginning (Day −11) of the ESFTAI (PREVAC). Pregnancy rates on Days 30 and 120 were greater (P ≤ 0.05) in PREVAC cows compared with VAC cows. In conclusion, pregnancy losses affected reproductive and overall efficiency of Brazilian cow-calf operations, and might be directly associated with BoHV-1, BVDV, and Leptospira spp. infections. Hence, vaccinating cows against these pathogens, particularly when both doses are administered before fixed-time AI, improved reproductive performance in Brazilian cow-calf systems.

Reproductive Hormone Profiles in Sows on Estrus Synchronization using Estradiol Dipropionate and Prostaglandin F&lt;sub&gt;2α&lt;/sub&gt;-Analogue and the Reproductive Performance in Female Pigs on Commercial Farms

Changes in ovarian structures and hormonal profiles in estradiol dipropionate (EDP)-induced pseudopregnant sows following PGF2α-analogue (PGF2α-A) administration and practicality of the estrus synchronization protocol using EDP and PGF2α-A on estrus expression and reproductive performance in commercial conditions were investigated. Pseudopregnancy was defined as absence of estrus maintained for at least 20 days after EDP treatment in this study. When 4 pseudopregnant sows induced by 20 mg EDP were treated with PGF2α-A as 0.175 mg cloprostenol twice at a 24-hr interval between 20 and 28 days after EDP treatment, plasma progesterone concentrations rapidly decreased after treatment. The luteinizing hormone surge and ovulation were detected in all sows. The number of ovulated follicles was 17.3 ± 1.1 (SEM). On commercial farms, 94.2% of 52 gilts and 95.2% of 21 sows received EDP became pseudopregnant. When these pseudopregnant females (48 gilts and 20 sows) were treated with PGF2α-A as described above, estrus was detected in all females at 6.1 ± 0.3 days for gilts and 5.5 ± 0.2 days for sows after the first PGF2α-A treatment. There were no significant differences in farrowing rate (85.0 - 100%), average total litter size (10.0 - 11.4), average born alive litter size (9.4 - 10.3) and average piglet birth weight (1.56 - 1.71 kg) between PGF2α-A treated pseudopregnant female pigs that were inseminated during synchronized estrus and females inseminated during spontaneous estrus. This study indicates that estrus synchronization programs using EDP and PGF2α-A are available as practical and convenient procedures for commercial pig farms.

Photoperiod length and the estrus synchronization protocol used before AI affect the twin pregnancy rate in dairy cattle

This study addresses potential management risk factors affecting the incidence of twin pregnancies in high-producing dairy cows. Special attention was paid to the estrus synchronization protocol used before the AI resulting in pregnancy. Possible factors affecting the twin pregnancy rate were analyzed through binary logistic regression procedures on 2015 pregnant cows from July 2010 to July 2011. Twin pregnancy was recorded in 361 of the 2015 pregnancy diagnoses made (17.9%). Twin pregnancy rates differed among herds (P < 0.001) and ranged from 12.4% to 23.9%. Based on the odds ratios, the risk of twin pregnancy was reduced by factors of 0.65 or 0.71 when AI was performed during the warm season or an increasing photoperiod, respectively and increased by a factor of 1.11 for each unit increase in lactation number; by factors of 4.57 or 6.33 in cows that received a progesterone-releasing intravaginal device (PRID) plus 500 or 750 IU of equine chorionic gonadotropin (eCG) 28 days before the pregnancy AI, respectively; by a factor of 2.39 in cows with an ovarian cyst diagnosed in the 14 days prior to AI and treated with prostaglandins (PG); by factors of 1.94 or 3.91 in cows that received two PG doses during the 14 days prior to AI or cows that following failed PRID treatment had received PG started over the 28 days prior to AI, respectively; and by a factor of 2.58 in cows that had previously delivered twins compared to cows delivering singletons. Our results indicate that cow factors, such as lactation number and previous twining, as well as environmental factors, such as photoperiod and season and management related to synchronization protocols affect significantly the incidence of twin pregnancies.

REDUCTION OF THE VOLUNTARY WAITING PERIOD BY USE OF HORMONAL PROTOCOLS AND FIXED-TIME ARTIFICIAL INSEMINATION (FTAI) IN DAIRY COWS

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&lt;0.01). The pregnancy rate in the G1, G2 and G3 was respectively 47.0, 46.1 and 35.8% (p&gt;0.05). In Conclusion: there was significant reduction in the voluntary waiting period in treated cows and higher pregnancy rate although not significant.