Estrus Synchronization Protocol Research Articles

86 VIABILITY AND FERTILITY OF RAM SEMEN CRYOPRESERVED WITH DIMETHYL ACETAMIDE AND TREHALOSE

Eleven semen samples from Santa Ines breed rams were cryopreserved with the objective of studying the effect of the dimethyl acetamide (DMA, 3%) or glycerol (GL, 6%) in an extender (Tris) with or without trehalose (TRE, 100 mOsmol) on post-thaw sperm viability and fertility. After the evaluation, the semen was diluted in extenders (TRIS+GL6%; TRIS+GL6%+TRE; TRIS+DMA3%; Tris+DMA3%+TRE) and then frozen. The post-thaw kinetic sperm parameters evaluated were the percentage of total motility (TM) and rapid spermatozoa (RAP), track speed (VCL), lateral amplitude of head (ALH), and linearity (LIN). The sperm viability was verified using the fluorescence markers propidium iodide (PMI, plasmatic membrane integrity), JC-1 (MMP, mitochondrial membrane potential), and FITC-PSA (ACI, acrosomal integrity). The spectrum of DNA sperm damage was assessed by single cell gel electrophoresis (Comet assay), and the measurements performed were tail moment (TMOM) and tail intensity (TINT; Comet Assay II software, Perceptive Instruments, Haverhill, UK). The sheep estrus synchronization protocol (n = 170) was 12 days of sponge with 60 mg of medroxyprogesterone acetate and 300 UI of eCG i.m. at sponge withdrawal. The ewes were inseminated on 57.5 h after sponge removal with 150 × 106 of live spermatozoa. The conception rates (CR) were verified for ultrasonography 45 days after insemination. The statistical analysis was performed using SAS software (SAS Institute Inc., Cary, NC, USA). The means (±SEM) of in vitro post-thaw sperm parameters and fertility rates are shown in Table 1. The greatest (P < 0.05) rates of TM and RAP for the GLY groups were observed in relation to the DMA ones. It was also verified the inferiority (P < 0.05) in the VCL and ALH for the trehalose extenders in both groups with GLY and DMA. The values (%) of TINT and TMOM were 14.9 and 03.9, 15.8 and 03.8, 14.7 and 02.9, and 16.6 and 04.4, respectively, for TRIS+GL6%, TRIS+GL6%+TRE, TRIS+DMA3%, and TRIS+DMA3%+TRE (P > 0.05). The integrity rates of all sperm membranes were superior for TRIS+GL6% in relation to TRIS+DMA3%. In conclusion, the DMA had apoor cryoprotective effect for ram semen. The addition of trehalose promoted negative effect on sperm kinetics, although it improved levels of PMM post-thawing in the DMA extender. The conception rate did not present a difference (P > 0.05) among the groups. Table 1.

24 EFFECT OF GnRH ON FIXED-TIMED ARTIFICIAL INSEMINATION PREGNANCY RATES OF WHITE-TAILED DEER

During the fall 2008 breeding season in Louisiana, 2 synchronization protocols for fixed-timed artificial insemination (FTAI) in White-tailed deer were assessed. The objective was to determine if GnRH at FTAI improved pregnancy rates in White-tailed deer. White-tailed does (n = 35) with a mean body weight of 65.8 kg (range: 54.0 to 79.8 kg) and average age of 5.9 years (range: 1.5 to 9.5 years) were stratified by weight, age, and last fawning date into 2 groups. Treatment and control synchronization protocols were randomly assigned to each group. Does were synchronized with a CIDR-G device for 14 d and were then subjected to either FTAI 60 hpost-CIDR removal (control, n = 17) or 100 μg (i.m) injection of GnRH at FTAI 60 h post-CIDR removal (treated, n = 18). At insemination (AI), insemination pipette placement score (IP; 0 = at cervical os to 3 = within uterine body), mucous scores (clear/cloudy, viscous/nonviscous, or no secretions), vulva assessments (hyperemic/nonhyperemic and swollen/not swollen), and sperm progressive motility were recorded. Does were inseminated with frozen-thawed sperm (5 × 107 progressively motile cells pre-freeze) from 2 fertile bucks stratified across each treatment group. Starting 28 d following AI, intact bucks (ITB) were introduced into both groups for natural mating. Pregnancy was determined via transrectal ultrasonography 73 or 80 d postinsemination. Does, confirmed pregnant via ultrasonography, had fawns within the reported gestation range of 187 to 222 days. Placentomes were visualized and measured in AI pregnancies (range: 32.7 to 56.2 mm in length), whereas pregnancies derived from ITB presented no identifiable placentomes. However, crown-rump measurements were obtainable from ITB pregnancies (range: 13.4 to 21.7 mm). Five does were not included in the final analyses as they were either lost to predators or removed because of illness. IP (1.4 ± 0.24 v. 1.3 ± 0.30; P = 0.671), mucous classifications (3.0 ± 0.35 v. 2.5 ± 0.39; P = 0.311), vulva assessments (2.1 ± 0.29, 1.7 ± 0.23; P = 0.223), and sperm motility (1.6 ± 0.16, 1.7 ± 0.22; P = 0.829) were not different for pregnant and nonpregnant AI does, respectively. Treatment did not affect AI pregnancy rates (53 v. 27%) or fecundity rates (1.6 v. 1.3 offspring/doe) for the GnRH treated and control groups, respectively. Addition of GnRH to a 14-day estrus synchronization protocol did not result in significantly higher pregnancy rates compared with controls. More studies are needed to determine the effect of GnRH on White-tailed pregnancies following FTAI protocols. We have demonstrated that differentiating pregnancies derived from AI and ITB could be accomplished by utilizing transrectal ultrasonography as early as 73 d postinsemination in White-tailed does.

Effects of a Progesterone-Based Oestrous Synchronization Protocol in 51- to 57-Day Postpartum High-Producing Dairy Cows

The aim of this study was to investigate the effect of applying a progesterone-based oestrous synchronization protocol at 51-57 days postpartum in high-producing dairy cows. The data analysed were derived from 1345 lactating cows. Cows between 51 and 57 days postpartum were assigned to the groups: control, PRID (receiving a progesterone-releasing intravaginal device for 9 days, and prostaglandin F(2α) 24 h before PRID removal) or GnRH-PRID (the same as the PRID group plus GnRH at PRID insertion). Oestrus was detected by using pedometers and confirmed by examination of the genital tract at AI. Oestrous and conception rates before days 71-77 postpartum, pregnancy loss in early pregnant cows or the cumulative conception rate registered on day 120 postpartum were considered as the dependent variables in four consecutive logistic regression analyses. Based on the odds ratios, the oestrous rate increased by a factor of 1.73 in cows showing oestrus before treatment for each unit increase in the number of previous oestruses; decreased by a factor of 0.44 in the control group with respect to the treatment groups; and by a factor of 0.61 in cows without luteal structures at treatment with respect to cows with corpora lutea. The conception rates of cows inseminated before days 71-77 postpartum remained similar across the groups, whereas the likelihood of pregnancy loss for cows becoming pregnant during this period was 0.11 times lower in the PRID group than in the control. Based on the odds ratio, the likelihood of a higher cumulative conception rate on day 120 postpartum: increased in cows showing oestrus before treatment by a factor of 1.41 for each unit increase in the number of previous oestruses, was reduced 0.56-fold in control cows compared with treated cows, and was also reduced by a factor of 0.98 for each kilogram of milk production increase recorded at treatment. In conclusion, although oestrous synchronization programmes performed in this study did not improve fertility, cows treated with progesterone could be inseminated earlier than untreated cows, such that the treatments increased the cumulative pregnancy rates determined on day 120 postpartum. In addition, fewer pregnancy losses were observed in early pregnant cows in the PRID group than the GnRH-PRID group.

Sincronização do estro e da ovulação utilizando protocolos de curta duração durante a pré-estação reprodutiva em ovelhas Suffolk

Estrus and ovulation synchronization using short-term protocols during the previous reproductive season in Suffolk ewes. This study was carried out with the objective of examining the effect of the short-term estrus synchronization protocol. Ewes were divided in four groups: Control Group (MAP sponges for 12 days, and eCG at withdrawal); Groups I, II and III used the sponge for four days, and 100 g of PGF was applied at withdrawal; and additionally, Group I (0.1 mg of Estradiol benzoate - EB, in the sponge placement, and in the withdrawn 400 UI of eCG and 50 g of GnRH 48h later); Group II (35 mg of injectable progesterone and 0.1 mg of EB in the sponge placement, and 400 UI of eCG at withdrawal, and 50 g of GnRH 48h after); Group III (35 mg of injectable progesterone and 0.2 mg of EB in the sponge placement, and 400 UI of eCG at withdrawal, and 50 g of GnRH 56h after). Exams were accomplished for ultrasound and determine the plasmatic concentrations of progesterone and observations of the beginning the estrus and the ovulation. The lack of eCG in Group I caused this protocol to be less efficacious in induction and synchronization of estrus and ovulation. The Control Group had a greater synchronization of estrus and ovulation.

Control of the estrous cycle to improve fertility for fixed-time artificial insemination in beef cattle: A review1

Early estrus-synchronization protocols focused on regressing the corpus luteum (CL) with an injection of PGF(2alpha) followed by detection of estrus or involved the use of exogenous progestins that prevent estrus from occurring. Later, protocols combining the use of PGF(2alpha) and exogenous progestins were developed. Gonadotropin-releasing hormone was utilized to control follicular waves, synchronize ovulation, or to luteinize large dominant follicles. Our research aimed to develop reliable protocols that 1) relied solely on fixed-timed AI (TAI); 2) required a maximum of 3 animal handlings, and 3) were successful in estrous-cycling and noncycling females. In cows, insertion of an intravaginal progesterone insert during the 7-d interval between the initial GnRH and PGF(2alpha) injections enhanced pregnancy rates by 9 to 10%. In a multi-location study, a TAI protocol yielded pregnancy rates similar to a protocol involving detection of estrus plus a fixed-time clean-up AI for females not detected in estrus (54 vs. 58%, respectively, for cows and 53 vs. 57%, respectively, for heifers). Initiation of estrous cycles in noncycling cows is likely the primary manner in which beef producers may improve fertility in response to estrus synchronization and TAI protocols. Treatment of noncycling females with progesterone and GnRH increases the percentage of cycling females and improves fertility to a TAI, but inducing cyclicity with hCG failed to enhance fertility in TAI protocols. Supplementing progesterone after TAI failed to increase pregnancy rates in beef cattle. In contrast, administration of hCG 7 d after TAI induced an accessory CL, increased progesterone, and tended to enhance pregnancy rates. Development of TAI protocols that reduce the hassle factors associated with ovulation synchronization and AI provide cattle producers efficient and effective tools for capturing selective genetic traits of economic consequences. Location variables, however, which may include differences in pasture and diet, breed composition, body condition, postpartum interval, climate, and geographic location, affect the success of TAI protocols.

Comparison of controlled internal drug release insert-based protocols to synchronize estrus in prepubertal and estrous-cycling beef heifers1

The objective of the experiment was to examine the necessity of adding a GnRH injection to a 14-d controlled internal drug release (CIDR)-based protocol for synchronization of estrus in beef heifers that were prepubertal or estrous-cycling at the initiation of treatment. The hypothesis tested was that the addition of GnRH in a CIDR-based estrus synchronization protocol would increase the synchrony of estrus after PGF(2alpha) (PG). Beef heifers (n = 285) were assigned to 1 of 2 treatments within reproductive tract scores (2 or 3 = prepubertal; 4 or 5 = estrous-cycling) by age and BW. Heifers assigned to CIDR Select received a CIDR insert (1.38 g of progesterone) from d 0 to 14 followed by GnRH (100 microg, intramuscularly) on d 23 and PG (25 mg intramuscularly) on d 30. Heifers assigned to CIDR-PG received a CIDR insert from d 0 to 14 and PG on d 30. Heifers were fitted with a HeatWatch estrus detection system transmitter at the time of PG administration for continuous estrus detection during the synchronized period (0 to 144 h after PG); AI was performed 12 h after estrus onset. Estrous response did not differ (P = 0.43) between treatments (94% CIDR Select, 98% CIDR-PG). Mean interval to estrus after PG was 7 h shorter (P = 0.01) and variance for interval to estrus was reduced (P < 0.01) among CIDR-PG-treated compared with CIDR Select-treated heifers. Conception rate to AI tended (P = 0.09) to be greater for CIDR-PG heifers (67%) compared with CIDR Select heifers (58%), and AI pregnancy rate was greater (P = 0.05) for CIDR-PG heifers (66%) compared with CIDR Select heifers (55%). Final pregnancy rate at the end of the breeding season was similar for the 2 treatments (81% for both; P = 0.94). We conclude that the administration of GnRH 9 d after CIDR removal in the CIDR Select protocol is not required to facilitate an improvement in the synchrony of estrus in beef heifers.

Effects of rumen-protected polyunsaturated fatty acid supplementation on reproductive performance of Bos indicus beef cows1

Five experiments evaluated the effects of rumen-protected PUFA supplementation on reproductive function of Bos indicus beef cows. In Exp. 1, 910 lactating primiparous Nelore cows were randomly assigned to receive 0.4 kg/d of a protein-mineral mix in addition to 0.1 kg/d of a rumen-inert PUFA source (PF) or 0.1 kg/d of kaolin (rumen-inert indigestible substance; control), from the beginning of estrus synchronization protocol (d -11) until 28 d after fixed-time AI (TAI; d 28). Cows supplemented with PF had greater (P = 0.04) pregnancy rates compared with control cows (51.2 vs. 39.6%). In Exp. 2, 818 lactating primiparous Nelore cows were assigned to the same TAI schedule from Exp. 1 and randomly allocated to receive 1) control from d -11 to 28, 2) PF from d -11 to 16 and control from d 17 to 28, or 3) PF from d -11 to 28. Cows receiving PF until d 28 had greater (P = 0.02) pregnancy rates compared with control cows and tended to have greater (P = 0.10) pregnancy rates compared with cows receiving PF until d 16 (42.9, 31.3, and 35.8%, respectively). In Exp. 3, 435 nulliparous and multiparous lactating B. indicus-crossbred cows were randomly assigned to receive control or PF from the end of synchronization protocol (d 0) until 21 d after fixed-time embryo transfer (d 28). Cows supplemented with PF had greater (P = 0.07) pregnancy rates compared with control cows (49.6 vs. 37.7%). In Exp. 4, 504 lactating multiparous Nelore cows were randomly assigned to receive PF or a similar supplement containing a rumen-protected SFA source (SF) for 28 d beginning after TAI. Cows supplemented with PF had greater (P = 0.02) pregnancy rates compared with SF cows (47.9 vs. 35.5%). In Exp. 5, 9 nonlactating, nonpregnant, ovariectomized Gir x Holstein cows inserted with an intravaginal progesterone (P4)-releasing device were stratified by BW and BCS and divided into 3 squares. Squares were randomly assigned to receive control, PF, or a protein-mineral mix containing 0.2 kg/d of rumen-inert PUFA source (PF2), in a Latin square 3 x 3 design containing 3 periods of 14 d each. Cows supplemented with PF had greater (P = 0.03) mean serum P4 concentrations compared with control and PF2 cows (1.81, 1.66, and 1.68 ng/mL, respectively). These results indicate that supplementing 0.1 kg/d of rumen-inert PUFA to beef cows, particularly after breeding, may be a method of enhancing their reproductive performance, perhaps by increasing circulating P4 concentrations.

EFEITO DA SINCRONIZAÇÃO DO ESTRO COM DUPLA APLICAÇÃO DE D-CLOPROSTENOL ASSOCIADA OU NÃO À eCG SOBRE O DESEMPENHO REPRODUTIVO DE CABRAS ½ BOER/SRD EXPLORADAS NA REGIÃO SEMIÁRIDA DO NORDESTE DO BRASIL

he aim of this study was to evaluate the effect of double injection of d-cloprostenol associated or not with equine chorionic gonadotrophin (eCG) over the reproduction performance of ½ Boer/non-genotype goats raised in the semi-arid region of North-eastern Brazil. Forty goats were distributed into two estrus synchronization protocols, as following: T1 (n = 20) two injections of 75 µg d-cloprostenol at seven days interval; T2 (n = 20), similar to the previous protocol, differing only by the addition of 300 IU eCG at the last d-cloprostenol injection. Percentage of animals in estrus (65% vs. 85%) and interval from the end of treatment to estrus onset (22.8 ± 13.4 h vs. 17.2 ± 7.6 h) did not differ (P>0.05) between T1 and T2, respectively. However, T2 showed a larger estrus length (P KEY WORDS: Estrus synchronization, goats, gonadotrophin, productive performance, prostaglandin.

Pregnancy Rates and Progesterone Concentrations Following Ovsynch and CIDR Estrus Synchronization and Artificial Insemination Protocols.

Pregnancy Rates and Progesterone Concentrations Following Ovsynch and CIDR Estrus Synchronization and Artificial Insemination Protocols.

Development of estrous synchronization protocols using melengestrol acetate in Bos indicus cattle

Five experiments were conducted on commercial farms in Brazil designed to develop the basis for an estrus synchronization protocol using melengestrol acetate (MGA) in Bos indicus cattle. These studies resulted in the development of the following protocol: 0.5 mg x d(-1) of MGA between d -14 and -1; 2.0 mg i.m. injection of estradiol cypionate on d -9; 48 h temporary weaning between d 0 and 2; and natural service beginning on d 0. The basis of this protocol was to induce estrous cyclicity before postpartum loss of body condition, prevent premature luteolysis, eliminate the need for labor required to detect estrus, and consequently increase the likelihood of pregnancy early during the postpartum period. This treatment effectively induced estrous cyclicity among anestrous cows, synchronized estrus activity, and prevented premature luteolysis with no negative effect on pregnancy.

Heifer synchronization using 7-11 synch or 7-11 synch + CIDR (2009)

Two aims of heifer estrus synchronization protocols are to induce prepubertal heifers to start cycling by the beginning of the breeding season and to shorten time spent in estrous detection. Use of progestins such as melengestrol acetate (MGA) and intravaginal progesterone-releasing devices (CIDR) can induce prepubertal heifers to begin cycling as well as synchronize estrus in cycling heifers. In past years, a timed artificial insemination protocol (7-11 COSynch) has been tested with varying results. Pregnancy rates using 7-11 COSynch have typically ranged from 40 to 60%. The objective of the current trial was to determine the effect of a similar heat-detection protocol (7-11 Synch) with or without a CIDR. We compared heat response, interval to estrus, and conception rates in beef heifers.

COMPARAÇÃO DE DIFERENTES PROTOCOLOS PARA A SINCRONIZAÇÃO DE ESTRO E INSEMINAÇÃO ARTIFICIAL EM TEMPO FIXO EM VACAS DA RAÇA NELORE EM ANESTRO PÓS-PARTO

Neste estudo comparou-se diferentes métodos de sincronização de estro em 139 vacas da raça Nelore, em novembro de 2006 no município de Arapoti-PR. Foram utilizados quatro protocolos de sincronização de estro. No primeiro grupo (G1), foi utilizado pessário vaginal de poliuretano, impregnada com 360 mg de acetato de medroxiprogesterona (MAP) e 2 mg de Benzoato de Estradiol (BE) (=dia 0). Após a remoção (=dia 8), foi administrado 150 µg de cloprostenol, na submucosa vulvar (para todos os grupos) e 1 mg de cipionato de estradiol (ecp). No grupo dois (G2) foram utilizados pessários vaginais idênticos aos usados no G1. Na remoção (dia 8) foi administrado 0,75 µg de cloprostenol e 1 mg de cipionato de estradiol. No grupo três (G3), foi utilizado dispositivo intravaginal (sob a forma de Y) reaproveitado e impregnado com 360 mg de MAP e 2 mg de BE. Após 8 dias era removido e administrava-se 150 µg de cloprostenol e 1 mg de cipionato de estradiol. No grupo quatro (G4), foi utilizado identico dispositivo intravaginal ao usado no G3 e após removido(dia 8), aplicava-se 0,75 µg de cloprostenol sem o ecp. Para os grupos G1, G2, G3 a inseminação artificial (IA) foi realizada em tempo fixo às 56 horas após a retirada do pessário vaginal, sem a observação de estro. No G4 a IA era realizada 12 horas após a observação visual de estro. O diagnóstico de gestação foi efetuado por palpação retal após 60 dias. Concluiu-se que os diferentes protocolos de sincronização de estro utilizados não influenciaram a taxa de prenhez.

&lt;i&gt;In Vitro&lt;/i&gt; Assessment of Progesterone and Prostaglandin E&lt;sub&gt;2&lt;/sub&gt; Production by the Corpus Luteum in Cattle Following Pharmacological Synchronization of Estrus

We studied the secretory function of the corpus luteum (CL) in cows following different estrus synchronization protocols. Estrus was synchronized using one (n=4) or two injections (n=5) of prostaglandin F(2alpha) (PGF(2alpha); dinoprost), two injections of different analogues of PGF(2alpha) (aPGF(2alpha)), luprostiol (n=5) and cloprostenol (n=5), at eleven-day intervals, a gestagen implant (norgestomet, n=5, for 10 days) or norgestomet together with a subsequent dinoprost injection on the day of implant removal (n=5). CL samples were collected by ovariectomy on Day 7-8 of the estrous cycle. Luteal strips were stimulated with LH (100 ng/ml) or prostaglandin E(2) (PGE(2), 10(-6)M) for 24 h in culture media. The progesterone (P(4)) and PGE(2) concentrations in the media were measured by enzyme immunoassay. In the control CL (spontaneous estrus; n=5), LH and PGE(2) stimulated P(4) and PGE(2) (P<0.001). The effects of both factors on P(4) were reduced in the CL following dinoprost- and cloprostenol-synchronized estrus (P<0.05) and were absent in the luprostiol-synchronized CL (P>0.05). In the norgestomet-synchronized CL, the stimulatory effects of LH and PGE(2) were higher compared with the CL synchronized by aPGF(2alpha) (P<0.05). Pharmacological manipulation of the estrous cycle using aPGF(2alpha) may cause lower P(4) secretion. Estrus synchronization inhibited CL sensitivity to luteotropic factors. Therefore, attention should be focused on the estrous synchronization method in both in vivo and in vitro studies of CL functions in cattle.

Comparison of Two Short Estrus Synchronization Protocols and Timed Artificial Insemination in Dairy Cows

Leyva, C. and Mellado, M. 2008. Comparison of two short estrus synchronization protocols and timed artificial insemination in dairy cows. J. Appl. Anim. Res., 34: 105–108. To compare two short protocols for synchronization of estrus and timed-artificial insemination (TAI), 79 pluriparous non-pregnant Holstein cows with active corpus luteum (CL) were selected from a commercial dairy farm in northern Mexico and allotted to one of two treatments in a completely randomised design. Group 1 cows (n=39) received an injection of 15 mg PGF2α and 24 h later received 1 mg estradiol cypionate (ECP). Two days later cows were inseminated by appointment. Cows in group 2 received an injection of 100 fig GnRH 48 h after the PGF2α injection and underwent a timed AI at 16–20 h after the GnRH injection. At the moment of CL diagnosis, blood samples were collected from all cows and analyzed for progesterone, to corroborate CL diagnosis. Pregnancy rates of cows in estrus were similar for both treatment groups with similar percentage of cows displaying intense estrus. The present study showed that estrus of lactating dairy cows can be successfully synchronized with short synchronization protocols using either GnRH or ECP, although the inaccuracy of rectal palpation for determining the presence of a functional corpus luteum lead to lower pregnancy rates than those attained with traditional protocol currently available to dairy producers.

Progesterone, Follicular, and Estrual Responses to Progesterone-Based Estrus and Ovulation Synchronization Protocols at Five Stages of the Estrous Cycle

The objective was to monitor changes in ovarian status in heifers exposed to a progesterone insert with or without concurrent GnRH injection. Estrus was manipulated in 283 heifers (31 breeding clusters) by administering GnRH, progesterone, and PGF2α at 5 stages of the estrous cycle. Estrus was presynchronized with a progesterone insert (CIDR) for 7 d before PGF2α was administered 24h before insert removal. Successive clusters of heifers were assigned to treatments (2 heifers per treatment) on cycle d 2, 5, 10, 15, and 18. Treatments consisted of a progesterone insert (d 0) for 7 d plus: 1) PGF2α on d 6, 24h before insert removal (early PGF); 2) GnRH on d 0 + early PGF2α (GnRH + early PGF); 3) PGF2α at insert removal (late PGF); and 4) GnRH on d 0 + late PGF (GnRH + late PGF). Controls received GnRH on d 0 and PGF2α on d 7. Ovaries were scanned by transrectal ultrasonography on d 0, 2, 7, 9, and 11 to assess follicle diameters and ovulation. Blood was collected on d 0, 2, 6, 7, 8, and 9 to quantify serum concentrations of progesterone. Insemination occurred after detected estrus or by timed artificial insemination (TAI) at 64h after insert removal. Only 25% of 141 GnRH-treated heifers ovulated by d 2; twice as many ovulated when treatment was initiated on d 5 (46.4%) than on other cycle days (20.3%). Diameters of the largest follicle exposed to GnRH on d 0, 2, 7, or 9 did not differ regardless of whether ovulation occurred. Small treatment and stage of cycle differences in diameter of the largest follicle were detected on d 2, 7, and 9. Compared with controls, progesterone concentration was greater in all progesterone-treated heifers on d 2 and 6. Early- vs. late-PGF treatment resulted in less progesterone on d 7 and 8. Pregnancies per AI were less after TAI (44%) than after detected estrus (56%) and were less in controls than in all progesterone treatments. Heifers in which treatments were initiated on d 10 of the cycle had the most consistent (estrus vs. TAI) pregnancies per AI (65.4%) compared with other cycle days. Compared with controls, more progesterone-treated heifers ovulated by 96h after insert removal. Application of the progesterone insert reduced variance of the interval to estrus after insert removal (or PGF2α injection in controls) by 1.6-fold compared with controls. These results do not support the use of GnRH in a progesterone-based synchronization protocol.

Estrus Synchronization and Superovulation in Goats: A Review

The study was intended to review the recent developments and advances of estrus synchronization and superovulation protocols in goats with a view to improve oocytes/embryo recovery for In Vitro Production (IVP) efficiencies. Although a number of estrus synchronizing protocols has been developed in goat the most widely used one is the treatment of progesterone for 9-11 days followed by a luteolytic dose of prostaglandin administered in the period 48 h prior to removal of intravaginal sponge. Until now, Controlled Internal Drug Release (CIDR) device and subcutaneous implants are more preferable than sponges. Ovulation in goat can be synchronized more precisely by administering Gonadotrophin Releasing Hormone (GnRH) around the time of estrus that improves the success of fixed-time Artificial Insemination (AI) and oocytes or embryos collection at a controlled stage. Superovulation is the hormonal treatment for increasing a large number of oocytes that ultimately accelerate genetic improvement in any species. Generally an exogenous follicle-stimulating gonadotrophin is administered that mimics the effect of Follicle Stimulating Hormone (FSH) near the end of the luteal phase of the cycle (9-11 days) or around 48 h before the end of the synchronizing treatments. The major commercial products applied are equine Chorionic Gonadotrophin (eCG) or Pregnant Mare Serum Gonadotrophin (PMSGT) and FSH. This review paper describes estrus synchronization, ovarian superovulation as well as the normal physiology of estrous cycle and ovulation in goats. © 2008 Asian Network for Scientific Information.

Induction of ovarian follicular wave emergence in wapiti ( Cervus elaphus)

Two experiments were done to test the effects of treatments designed to electively induce ovarian follicular wave emergence in wapiti for the purpose of group synchronization. In Experiment 1, hinds were assigned randomly to three groups and given saline im (controls; n = 5), 5 mg of estadiol-17ß im ( n = 4), or 5 mg estradiol-17ß plus 100 mg progesterone im ( n = 5). In Experiment 2, hinds were assigned randomly to two groups and given no treatment (controls; n = 6), or transvaginal ultrasound-guided follicle ablation ( n = 7). In both experiments, ovarian follicular dynamics were monitored by daily transrectal ultrasonography from Day 0 (day of treatment) to Day 9. In Experiment 1, blood samples were collected at each examination for measurement of serum concentrations of progesterone and FSH. Both experiments were conducted during the late anestrous period (July and August). The mean (±S.E.M.) day of wave emergence did not differ between the control and estradiol alone groups, but tended to be later in the estradiol plus progesterone group Day 4.0 ± 0.7, Day 3.5 ± 0.3, and Day 5.2 ± 0.2, respectively; P = 0.06). The interval from treatment to wave emergence was less variable in the estradiol plus progesterone group ( P < 0.05) and tended to be less variable in the estradiol-alone group ( P = 0.07) than in the control group. The day of wave emergence was more variable ( P < 0.05) and tended to be later ( P = 0.10) in the control group compared to the ablation group (Day 2.5 ± 0.8 versus Day 1.4 ± 0.2). All three treatments were effective in synchronizing ovarian follicular wave emergence among a group of wapiti hinds. Follicle ablation may be an alternative method for synchronization of follicular waves in estrus synchronization and superstimulatory protocols.

Equine chorionic gonadotrophin and porcine luteinizing hormone to shorten and synchronize the wean-to-breed interval among parity-one and parity-two sows

Objective: To determine the efficacy of an estrus and ovulation synchronization protocol utilizing equine chorionic gonadotropin (eCG) and porcine luteinizing hormone (pLH) on the wean-to-breed interval (WBI), farrowing rate, and litter size in parity-one and parity-two sows. Materials and methods: Parity-one (n = 1167) and parity-two sows (n = 1196) from a total of eleven farms across Canada were each randomly assigned either to a treatment (596 parity-one and 599 parity-two sows) or control group (571 parity-one sows and 597 parity-two sows). Treated sows received 600 IU eCG intramuscularly (IM) at weaning and 5 mg pLH IM at observed estrus. Detection of estrus behaviour was facilitated by twice daily boar exposure for 20 minutes beginning 24 hours after weaning. All sows were inseminated at 12 and 32 hours after the onset of behavioural estrus. Results: On average, the WBI was lower by approximately 1 day among treated parity-one sows, and by 0.3 day among treated parity-two sows. In addition, the overall breeding period was shorter among treated sows, especially among parity-one sows. There was no treatment effect on farrowing rate or litter size. Implications: Administration of exogenous eCG and pLH with subsequent timed double insemination may shorten the WBI in weaned parity-one and parity-two sows, allowing for more predictable crate utilization and a narrower range in gestational age in the farrowing room.

The effect of estrus synchronization treatments on somatic cell count of transitional-anestrus Awassi ewes’ milk

Fifty-three transitional-anestrus Awassi ewes, randomly assigned to three groups: fluorogestone acetate (FGA, n = 18), FGA-Prostaglandin (FGA-PGF, n = 18) and control (n = 17), were used to examine the effect of estrus synchronization protocols and steroid hormones concentrations on milk somatic cell count (SCC). Intravaginal FGA sponge was inserted for 13 days and 600 IU equine chorionic gonadotropin was administered for ewes of FGA and FGA-PGF groups at the time of sponge removal (day 0). In addition, 10 mg was administered to ewes of FGA-PGF group on day 0. Blood and milk samples were collected from all ewes on days -13, -6, 0, 1, 2, 7 and 14. Estradiol had significant positive correlation with the SCC during the periods of sponge insertion (P = 0.015, r = 0.235) and within two days (P = 0.063 r = 0.23) after sponge removal with no correlation with SCC of both udder halves during the luteal phase. Progesterone concentrations, on the other hand, had a significant positive correlation (P < 0.001; r = 0.420) with the SCC of both udder halves during the luteal phase of the experiment, but not during the periods of sponge insertion and expected estrus. SCC returned under the influence of endogenous progesterone on days 7 and 14 to pre-synchronization values. In conclusion, sheep milk SCC is affected significantly with induction of estrus and steroid hormones concentrations. However, peak SCC recorded during estrus was far below the upper limit of the current standard for normal milk. With the current standards for SCC of 1,000,000/ml as legal limit for abnormal milk control programs in sheep, estrus synchronization programs and the estrus status should not be considered when bulk-tank milk SCC is being investigated, but should be considered during the process of setting new standards.

Concentrations de l’hormone lutéinisante et de la progestérone chez des vaches zébus Azawak soumises à différents protocoles de synchronisation de l’oestrus

Quinze vaches zébus Azawak ont été soumises à deux protocoles de synchronisation de l’oestrus. Les concentrations plasmatiques de LH et le pourcentage des femelles ayant exhibé un comportement d’oestrus ont été répertoriés. Le premier traitement de synchronisation (T1, n = 9) a été effectué avec des implants sous-cutanés de norgestomet placés sous la peau de l’oreille pendant 10 jours. Le traitement a été complété par des injections de valérate d’oestradiol, de prostaglandine F2α et de pregnant mare serum gonadotropin (PMSG). Le deuxième protocole (T2, n = 6) a consisté en deux injections de prostaglandine F2α à 11 jours d’intervalle, suivies d’une injection de PMSG deux jours après la deuxième injection de prostaglandine. Des échantillons de sang ont été prélevés à trois heures d’intervalle pendant cinq jours après le retrait de l’implant (T1) ou l’injection de PMSG (T2) pour mesurer les taux de LH. Le taux d’oestrus induit a été plus élevé chez les vaches du groupe T2, mais cette différence n’a pas été significative. En général, le temps observé entre la fin du traitement et le début de l’oestrus a été plus court chez les femelles traitées au norgestomet (35,9 ± 3,9 h) que chez celles traitées à la prostaglandine (49,5 ± 5,8 h). Sept sur les neuf femelles traitées au norgestomet et seulement deux sur les six traitées à la prostaglandine ont présenté un pic de LH. L’intervalle moyen entre la fin des traitements et le pic de LH a eu tendance à être plus long chez les femelles traitées à la prostaglandine que chez celles traitées au norgestomet. Une femelle a présenté des concentrations de LH anormalement élevées après le retrait de l’implant. Toutefois, aucun pic de LH n’a été observé pendant la période de suivi.