Treatment alternatives to induce follicular wave emergence for timed-AI in lactating dairy Cows.

Two experiments evaluated the effect of different hormonal treatments to synchronize follicle wave emergence on follicle dynamics and pregnancies per AI (P/AI) in estradiol (E2)/progesterone (P4) timed-AI (TAI) protocols in lactating dairy cows. In Experiment 1, lactating, primiparous Holstein cows (n = 36) received a P4 releasing device (Day 0) and were allocated at random to one of the following three treatment groups: Group EB received 2 mg E2 benzoate (EB) intramuscularly (i.m.), Group EB + GnRH received 2 mg EB+20 µg buserelin (GnRH) i.m., or Group EB + P4 received 2 mg EB + 100 mg of injectable P4 (iP4) in oil i.m. All cows received 0.150 mg D-Cloprostenol on Days 7 and 8 followed by P4 device removal, 400 IU eCG and 1 mg ECP on Day 8. Daily ultrasound examinations revealed that although the interval from P4 device removal to ovulation was not affected by treatment, cows that received EB + GnRH had an earlier (P < 0.05) emergence of the new follicular wave (Day 2.6 ± 0.2) than the other two treatment groups (Days 3.5 ± 0.3 and 6.1 ± 0.3, for EB and EB + P4, respectively). In Experiment 2, 808 lactating cows were assigned randomly to the three treatments evaluated in Experiment 1, and all the cows were TAI to determine P/AI. Cows in the EB + GnRH group had greater P/AI (57.4 %, P < 0.01) than those in the EB (44.6 %) or EB + P4 (45.7 %) groups. In conclusion, the administration of GnRH, but not iP4, on the day of insertion of a P4 device improves P/AI in lactating dairy cows synchronized for TAI with an estradiol/P4-based protocol.

Early versus late body condition score loss in dairy cows: Reproductive performance.

This study aimed to compare milk production and reproductive performance in high yield Holstein cows that lose BCS early and late in the postpartum period. Lactating dairy cows (n = 76) were received first timed AI at 60 to 75 DIM using the farm-managed estradiol-progesterone-GnRH-based timed AI protocol. The BCS of all cows was daily evaluated by automated BCS cameras. Aiming to evaluate the effect of the days in milk (DIM) in which a cow reached the nadir BCS on the reproductive parameters, cows were separated into two groups: early BCS loss (n = 42), cows that reached the nadir BCS ≤ 34 DIM, and late BCS loss (n = 34), cows that reached the nadir BCS > 34 DIM. The optimal cut-off point for determining the relationship between days to nadir BCS and pregnancy by 150 DIM (P150) was calculated using the receiver operating characteristic (ROC) curve. From the ROC analysis, the cut-off was 34 DIM (Se, 80.9%; Sp, 66.7%; AUC, 0.74; P < 0.01). No differences (P>0.05) were detected between groups on the BCS and milk production. The average of milk production in both groups was 46.65 ± 6.15 Kg/day. Cows that reached the nadir BCS early postpartum presented lower (P < 0.01) calving interval and greater (P < 0.01) pregnancy at first AI and P150. In summary, cows that lost BCS early had better reproductive performance and had similar milk yield compared with cows that lost BCS late in the postpartum period.

Effect of the addition of GnRH and a second prostaglandin F2α treatment on pregnancy per artificial insemination in lactating dairy cows submitted to an estradiol/progesterone-based timed-AI protocol.

Two experiments determined whether the addition of GnRH at the beginning of an estradiol (E2)/progesterone (P4)- based synchronization protocol and/or a second dose of prostaglandin F2α (PGF2α) the day before P4 device removal improves pregnancy rate in lactating dairy cows. On Day 0, all cows received a CIDR-B device and 2 mg i.m. estradiol benzoate, and half received 200 µg i.m. gonadorelin acetate (GnRH). On Day 7, cows were further subdivided to receive PGF2α (500 µg i.m. cloprostenol) or no PGF2α treatment. On Day 8, CIDR-B were removed, and all cows received PGF2α, 1 mg estradiol cypionate and 400 IU eCG i.m., and an estrus detection aid. Experiment 1 was designed to evaluate the effect of treatments on follicular development from P4 device removal to ovulation, expression of estrus, time of ovulation and serum P4 concentrations. Cows (n = 76) were examined by ultrasonography and bled for serum P4 determinations every 12 h from the time of P4 device removal but were not inseminated. In Experiment 2, all cows (n = 1036) were inseminated based on estrus detection using tail-paint. Cows with >50% of the paint rubbed-off by 48 h after P4 device removal were inseminated at that time, whereas those not in estrus received 100 µg i.m. of GnRH and were inseminated 12 h later. In Experiment 1, the interval from P4 device removal to ovulation was 71.7 ± 1.5 h and did not differ among groups. However, cows that received 2 injections of PGF2α had a greater (P < 0.01) estrus rate and lower (P < 0.01) P4 concentrations at 48 h after P4 device removal than those that received 1 PGF2α (estrus rate: 86.8% vs 68.4% and P4 concentration: 0.12 ± 0.01 vs 0.36 ± 0.07, for 2 and 1 PGF2α, respectively). In Experiment 2, estrus rate was also influenced by the number of PGF2α treatments, regardless of whether cows received or did not receive GnRH on Day 0 (2 PGF2α: 84.7%, 438/517 vs 1 PGF2α: 65.7%, 341/519; P < 0.01). Furthermore, there was a GnRH treatment by number of PGF2α treatments interaction (P < 0.05) on P/AI that was attributed to greater (P < 0.05) P/AI in cows that received GnRH on Day 0 and 2 PGF2α than in the other three treatment groups (EB+1 PGF2α: 45.2%, 119/263; EB+2 PGF2α: 45.8%, 119/260; EB + GnRH + 1 PGF2α: 45.7%, 117/256 and EB + GnRH + 2 PGF2α: 57.2%, 147/257). It was concluded that the addition of GnRH on Day 0 and a second dose of PGF2α the day before P4 device removal improves P/AI in lactating dairy cows synchronized with an estradiol/P4-based protocol.

Success of artificial insemination based on expression of estrus and the addition of GnRH to an estradiol/progesterone-based protocol on pregnancy rates in lactating dairy cows.

Three experiments evaluated the effects of insemination based on estrus expression or treatment with GnRH, on the time of ovulation and pregnancy rates to AI (P/AI) in dairy cows. All cows were treated with a P4 device for 8 d, estradiol benzoate at device insertion and prostaglandin F2α, estradiol cypionate and eCG at device removal. In Experiment 1, P/AI was less (P < 0.01) when all cows were inseminated at 48 h after device removal (31%) than when cows showing estrus at 48 h were inseminated at that time and those not in estrus received GnRH and were inseminated 12 h later (53%). In Experiment 2, cows in estrus by 48 h ovulated earlier than cows that were not in estrus but received GnRH and those that did not receive GnRH. Cows that were in estrus and inseminated at 48 h (47.8%) and those not in estrus at 48 h but inseminated at 60 h (53.4%) had greater P/AI (P < 0.05) than cows that were in estrus at 48 h but were inseminated at 60 h (29.7%) or inseminated at 48 h in the absence of estrus (19.4%). In Experiment 3, GnRH treatment of cows not showing estrus at 48 h and inseminated at 60 h had greater P/AI (58.5%; P < 0.05) than those not treated with GnRH but inseminated at 60 h (39.5%). Artificial insemination based on estrus expression and the inclusion of GnRH in those not in estrus increased P/AI in lactating dairy cows.

Effects of estradiol cypionate dose as an ovulatory stimulus on reproductive performance of lactating dairy cows during the summer season.

This experiment was designed to evaluate the effects of increasing doses of estradiol cypionate (ECP) on reproductive function of lactating dairy cows during the summer. In Exp. 1, 643 lactating Holstein cows were blocked by parity and assigned to receive 1) an intravaginal P4 device (1.9 g of P4) and 2.0 mg of estradiol benzoate on day -11, 25 mg (i.m.) of dinoprost tromethamine on day -4, 1.0 mg (i.m.) of estradiol cypionate and CIDR withdrawal on day -2, followed by TAI on day 0 (n = 326; ECP-1) or 2) the same synchronization protocol with 2.0 mg of ECP on day -2 (n = 317; ECP-2). In both treatments, cows were TAI on day 0 of the protocol, and cow rectal temperature was measured on days -2, 0, and 7. In Exp. 2, 608 lactating crossbred Holstein × Gir dairy cows were blocked by parity and enrolled to the same treatments as in Exp. 1, but on day 7, cows received one viable embryo into the uterine horn. In Exp. 1, a greater percentage of ECP-2 cows were detected on estrus (81.3 vs. 91.1%, respectively). A treatment × body condition score (BCS) interaction was observed on day 60 pregnancy per AI (P/AI), as ECP-2 cows with a BCS <2.75 had a greater P/AI vs. ECP-1, but an opposite result was observed in cows with a BCS ≥2.75. Regardless of treatment, there were effects of mean rectal temperature and heat stress events on P/AI. Treatment affected the diameter of the ovulatory follicle at TAI (ECP-1 = 15.3 mm vs. ECP-2 = 14.8 mm) and a greater percentage of ECP-1 cows had larger follicles (≥16.5 mm), but ECP-2 resulted in a greater incidence of early ovulatory cows (ovulating before day 0). Therefore, follicle diameter at TAI affected P/AI on day 60 in cows receiving ECP-2 and tended to affect ECP-1 cows. A treatment effect was observed on time to estrus following ECP treatments and a reduced proportion of ECP-2 cows showed estrus at TAI. Regardless of treatment, cows detected on estrus 48 h after ECP administration had a greater P/AI on day 60 vs. cows detected on estrus 24 h. In Exp. 2, a greater percentage of ECP-2 cows were detected on estrus (68.3 vs. 81.4%, respectively). In summary, a greater dose of ECP increased the percentage of animals expressing estrus, but it did not benefit the reproductive function of lactating dairy cows during the summer, regardless if animals were assigned to a TAI or timed-embryo transfer (TET) protocol.

In vitro sperm characteristics and in vivo fertility of sex-sorted and conventional semen in suckled Nelore cows at a traditional schedule for timed-AI with estrus detection / Características espermáticas in vitro e fertilidade in vivo de sêmen convencional e sexado em vacas Nelore pósparto submetidas à IATF tradicional com detecção de estro

The aim of this study was to assess in vitro sperm characteristics and pregnancies/AI (P/AI) of conventional and sex-sorted semen at timed-AI of suckled, multiparous Nelore cows. All cows (n=348) were submitted to a traditional estradiol/progesterone (P4)-based protocol. At 48h after P4-device removal, the estrous behavior was recorded, and AI was performed with conventional or sex-sorted semen from two bulls. The following sperm assessments were performed: CASA, Hyposmotic Test, sperm morphometry and chromatin structure by TB staining. P/AI were reduced (P<0.001) for sex-sorted compared to conventional semen in cows expressing estrus (27vs47%) or not (11vs.37%). Membrane integrity (Bull1: 30.3±9.6 vs. 52.3±12.4%, P=0.01; Bull2: 24.5±3.0 vs. 48.7±1.6%, P=0.006) and sperm concentration (Bulll: 23.2±0.6 vs. 43.0±0.8x10 sperm/mL, P<0.001; Bull2: 25.1+2.8 VS. 42.1±0.7x10 sperm/mL; P<0.001) were reduced in sex-sorted compared to conventional semen, for both bulls. Total and progressive motility were reduced in sex-sorted semen for Bull1 (TM: 49.7±15.9 vs. 94.9±1.9%, P=0.007; PM: 16.7±3.4 vs. 44.1±13.2%, P=0.009) and no differences were detected for Bull2 (TM: 45.0±17.5 vs. 68.2±19.1%, P=0.098; PM: 12.8±4.7 vs. 30.0±13.0%, P=0.065). Sperm ellipticity from sex-sorted was lower than conventional semen for Bull2 (0.306±0.01 vs. 0.342±0.02, P=0.02) and no difference was detected for Bull1 (0.332±0.01 vs. 0.330±0.01, P=0.55). Reduced in vivo fertility was observed for sex-sorted semen, regardless of estrous behavior. In vitro sperm quality of sex-sorted semen was compromised for both bulls, but differently affected for each sire.

O estudo teve como objetivo avaliar características espermáticas in vitro e a taxa de concepção (TC) de sêmen convencional e sexado em um programa de IATF tradicional de vacas Nelore pós-parto. Todas as vacas (n=348) foram submetidas ao mesmo protocolo de IATF à base de estradiol e de progesterona. Após 48 horas da retirada do implante, foi determinada a expressão de estro dos animais e a IA foi realizada com sêmen convencional e sexado de dois touros Angus. As seguintes características espermáticas foram avaliadas: análise computadorizada do sêmen, teste hiposmótico, morfometria espermática e estrutura cromatinica por meio da coloração com azul de toluidina. A TC foi menor (P<0,001) para sêmen sexado comparado ao convencional, em vacas que expressaram estro (27 vs. 47%) e que não apresentaram estro (11 vs. 37%). A integridade da membrana plasmática (Touro 1: 30,319,6 vs. 52,3+12,4%, P=0,010; Touro 2: 24,5+3,0 vs. 48,7±1,6%, P=0,006) e a concentração espermática (Touro 1: 23,2±0,6 vs. 43,0±0,8x10 sperm/mL, P<0,001; Touro 2: 25,1+2,8 vs. 42,1 +0,7x10'sperm/mL, P<0,001) foram menores no sêmen sexado comparado ao convencional, para ambos os touros. Motilidades total e progressiva foram menores no sêmen sexado comparado ao convencional para o Touro 1 (MT: 49,7±15,9 vs. 94,9±1,9%, P=0,007; MP: 16,7+3,4 vs. 44,1+13,2%, P=0,009), enquanto diferenças não foram detectadas no Touro 2 (MT: 45,0±17,5 vs. 68,2±19,1%, P=0,098; MP: 12,8±4,7 vs. 30,0±13,0%, P=0,065). Elipticidade espermática do sêmen sexado foi menor do que do sêmen convencional no Touro 2 (0,306±0,01 vs. 0,342±0,02, P=0,020), mas não houve diferença no Touro 1 (0,332±0,01 vs. 0,330±0,01, P=0,552). Reduzida fertilidade in vivo foi observada para o sêmen sexado em relação ao convencional, independentemente da expressão de cio das vacas. A qualidade seminal in vitro do sêmen sexado foi comprometida para ambos os touros, mas diferentemente afetada para cada reprodutor.

Administration of PGF2α at the moment of timed-AI using sex-sorted or conventional semen in suckled nelore cows with different intensity of estrus behavior.

The aim of this work was to evaluate pregnancy rates (PR) and ovulatory characteristics of Nelore cows receiving PGF2α at the time of AI (artificial insemination) in a progesterone(P4)/estradiol-based timed-AI protocol. We also compared the effects of PGF2α treatment at AI in cows inseminated with conventional or sex-sorted semen, with the absence or expression of estrus. In experiment 1, a total of 701 suckled, multiparous Nelore cows from two commercial beef farms were submitted to the same protocol. All cows received a 12.5 mg (IM) injection of dinoprost tromethamine (Dinoprost; Lutalyse®; PGF treatment) at days 7 and 9 of a timed-AI protocol. Following P4 device removal (day 11; D11), AI was performed 48 h later with conventional or sex-sorted semen from two different sires. At AI, cows received an additional dose of 12.5 mg (IM) of Dinoprost (PGF treatment) or 2.5 mL (IM) of sterile saline (Control). Estrus behavior was determined at D11 by activation of an estrus detection device (Estrotect®). The overall PR was 32.8% (n = 348) at Farm 1 and 42.3% (n = 353) at Farm 2 (P = 0.01). Despite PR differences between farms, the same factors affected PR at Farms 1 and 2. Body condition score (P = 0.02), estrus behavior (P = 0.01), and type of semen (P < 0.001) were factors affecting PR. Conventional semen had a 2.73x greater chance of successful pregnancy than sex-sorted semen. Cows displaying estrus had a 2.5x greater chance of successful pregnancy than cows that did not display estrus. No treatment effect (P = 0.67) was detected in cows receiving conventional or sex-sorted semen. However, there was a tendency (P = 0.08) for an interaction between treatment (PGF or control) and estrus behavior (estrus or no estrus). PGF2α at the time of AI tended to increase PR of cows that did not display estrus (P < 0.10). In experiment 2, 29 suckled, multiparous Nelore cows were compared using B-mode and Doppler ultrasongraphy to assess the ovulatory characteristics of cows receiving the 12.5 mg (IM) injection of Dinoprost (PGF treatment) or saline solution (control) at D11. No significant effects of PGF2α treatment at D11 were observed in follicular characteristics and/or ovulation performance. It was concluded that fertility of sex-sorted semen was lower than conventional semen, regardless of the PGF2α treatment. The 12.5 mg treatment of Dinoprost at AI did not accelerate the occurrence of ovulation; however, it was interesting to note that PGF2α treatment at timed-AI appeared to increase the fertility of cows that did not display estrus, independent of semen type.

Factors That Optimize Reproductive Efficiency in Dairy Herds with an Emphasis on Timed Artificial Insemination Programs.

Reproductive efficiency is closely tied to the profitability of dairy herds, and therefore successful dairy operations seek to achieve high 21-day pregnancy rates in order to reduce the calving interval and days in milk of the herd. There are various factors that impact reproductive performance, including the specific reproductive management program, body condition score loss and nutritional management, genetics of the cows, and the cow comfort provided by the facilities and management programs. To achieve high 21-day pregnancy rates, the service rate and pregnancy per artificial insemination (P/AI) should be increased. Currently, there are adjustments in timed artificial insemination (TAI) protocols and use of presynchronization programs that can increase P/AI, even to the point that fertility is higher with some TAI programs as compared with AI after standing estrus. Implementation of a systematic reproductive management program that utilizes efficient TAI programs with optimized management strategies can produce high reproductive indexes combined with healthy cows having high milk production termed "the high fertility cycle". The scientific results that underlie these concepts are presented in this manuscript along with how these ideas can be practically implemented to improve reproductive efficiency on commercial dairy operations.

Evaluation of presynchronization and addition of GnRH at the beginning of an estradiol/progesterone protocol on circulating progesterone and fertility of lactating dairy cows.

The objectives of this study were to determine if the utilization of a presynchronization strategy would improve fertility at first artificial insemination (AI) during an E2/P4 ovulation synchronization protocol with or without GnRH administration at the beginning of the protocol. This experiment was conducted using cows (n = 665) at their first postpartum service and the following breeding treatment: CIDR insertion and 2.0 mg of estradiol benzoate (EB) on day -11; 25 mg dinoprost tromethamine (PG) on day -4; PG, CIDR withdrawal, and 1.0 mg of estradiol cypionate (ECP) on day -2; timed-AI on day 0. At 31 ± 3 days postpartum, cows were randomly allocated to one of three treatments on a weekly basis: 1) -P + GnRH: cows assigned to the breeding protocol with 100 µg of GnRH on day -11, 2) P + GnRH: cows assigned to a presynchronization protocol using CIDR insertion +2 mg EB on day -28, PG + ECP and CIDR withdrawal on day -21, and beginning of the breeding protocol plus GnRH (100 µg) on day -11, and 3) +P-GnRH: cows assigned to a presynchronization protocol and the breeding treatment without GnRH on day -11. No treatment effects were observed on P/AI at the pregnancy diagnoses on days 32 and 60, or for pregnancy losses between days 32 and 60 of pregnancy whether analyses included all cows or only cows that ovulated near TAI. Moreover, milk yield negatively affected P/AI. Cows with greater circulating P4 concentrations on day -4 had greater P/AI on day 60. Cows without CL on day -11 had a reduced P/AI and this effect was more significant in cows not treated with GnRH. Cows assigned to -P + GnRH had the lowest circulating P4 concentration on day -4 (3.4 ± 0.16 ng/mL), followed by + P-GnRH (4.56 ± 0.17 ng/mL), and +P + GnRH (5.08 ± 0.17 ng/mL) cohorts. The data of the current study suggest that the combination of a Presynch and GnRH administration at the beginning of a TAI protocol was the most effective way to increase the % of cows with a functional CL and with elevated circulating P4 concentrations at the time of PG treatment.

Decreasing from 9 to 7 days the permanence of progesterone inserts make possible their use up to 5 folds in suckled Nellore cows.

This study aimed to evaluate the effects of decreasing permanence period of progesterone (P4) inserts from 9 (9d) to 7 (7d) days in timed-AI (TAI) protocol, as well as their reuse on pregnancy per AI (P/AI) during 7d protocol. At the beginning of all protocols, cows received 2 mg of estradiol benzoate (EB) and a vaginal insert containing 1.9 g of P4. In the 7d protocol, the P4 insert was removed, and cows were given 25 mg of prostaglandin F2α, 0.6 mg of estradiol cypionate and 300 IU of eCG 7 days later. In the 9d protocol, the P4 insert was removed, and cows received the same hormones that were administrated in 7d protocol, however, they were applied on the 9th day of the protocol. In the experiment I, 302 suckled Nellore cows were undergone to 7d protocol, and AI was performed 10-14 h later after estrus detection. In the experiment II, 679 suckled Nellore cows were assigned to receive either 7d or 9d protocols. In the experiment III, 999 suckled Nellore cows were assigned to receive either a new P4 insert (CIDR1), or a P4 insert used previously for 7 (CIDR2), 14 (CIDR3), 21 (CIDR4) or 28 (CIDR5) days, and 227 Nellore heifers received a P4 insert used previously for 21 (CIDR4) or 35 (CIDR6) days during the 7d protocol. When 7d protocol was used, 45% of cows exhibited estrus 48 h after P4 removal. Thus, the AI was performed 55 h after P4 removal in experiments II and III when 7d protocol was used. There was no difference in estrus detection rate (72 vs 74%; P = 0.60), ovulation rate (80 vs 88%; P = 0.13) and P/AI (56 vs 54%; P = 0.49) between 7d and 9d protocols, respectively. In the 7d protocol, the P/AI was similar (P = 0.72) using a new P4 insert (47%), or a P4 insert used previously for 7 (48%), 14 (45%), 21 (54%), or 28 (49%) days in Nellore suckled cows. In addition, P/AI was similar (P = 0.15) in heifers that received a P4 insert used previously for 21 (52%), or 35 (61%) days during the 7d protocol. In conclusion, cows submitted to 7d or 9d protocols had similar reproductive performance, and the reuse of P4 inserts up to 6 folds (five in suckled cows plus one in heifers) did not affect reproductive performance of Nellore cattle in 7d protocol.

Pregnancy rate in water buffalo following fixed-time artificial insemination using new or used intravaginal devices with two progesterone concentrations.

This study evaluated the pregnancy rate (PR) after timed artificial insemination (TAI) in water buffalo (Bubalus bubalis) during both non-breeding and breeding season, using either a new or reused intravaginal device (IVD) with two different progesterone concentrations. A total of 247 dairy buffalo cows were randomly assigned using a two-by-three factorial design and four replicates to the following groups: (1) new intravaginal device (IVD-New: DIB®, 1.0 g of P4, n = 51 or CIDR®, 1.38 g of P4, n = 55); (2) intravaginal device previously used once (9 days) (IVD-Used1x: DIB, n = 40 or CIDR, n = 51); or (3) intravaginal device previously used twice (18 days) (IVD-Used2x: DIB, n = 27 or CIDR, n = 23). On day 0, animals received the IVD plus 10.5 µg of buserelin acetate (GnRH) intramuscularly. On day 9, the devices were removed and 25 mg of PGF2α plus 500 IU of eCG was given intramuscularly. On day 11 (48 h after IVD withdrawal), animals received 10.5 µg of GnRH and were artificially inseminated 8-12 h later. Data were analyzed using Proc Logistic of SAS®. Animals that received IVD-New-DIB, had a significantly higher PR (62.7%; P = 0.0193) compared to animals that received IVD-New-CIDR (40%). Pregnancy rate was not negatively affected by reusing both types of IVD. Overall PR (new and reused devices) was higher (P = 0.0055) in the DIB group (62.7%) compared to the CIDR group (45%). In conclusion, PR was higher in buffaloes treated with devices containing 1.0 g of P4 (DIB®) compared to those receiving 1.38 g of P4 (CIDR®). Reusing the intravaginal devices did not affect negatively PR/TAI, suggesting that P4 concentrations within the TAI protocols in water buffaloes could be reduced, without impairing their fertility.

Assessment of different in vitro sperm challenges and in vivo fertility of bovine semen batches / Avaliação de diferentes desafios espermáticos in vitro e da fertilidade in vivo de partidas de sêmen bovino

The aim of this work was to submit sperm cells to different laboratory challenges and to compare in vitro results with in vivo semen fertility. Four different batches from the same Brangus bull were used in a timed-AI program of 332 Brangus cows. Each batch (B) was submitted to the following procedure: semen sample was thawed at 36°C for 30 seconds (control). Sperm motility parameters, plasma membrane integrity, sperm morphology, and concentration were assessed. Then, an aliquot of thawed sample was incubated in a water bath at 45°C for 40 min (thermal challenge group; TCG) and another aliquot was centrifuged at 500 xg (Percoll gradient 45%/90%) for 15 min (centrifugation challenge group; CCG). Centrifuged semen was also submitted to another thermal challenge, being incubated (water bath) at 45°C for 40 min (centrifugation + thermal challenge group; CTCG). At the end of each challenge (CCG, TCG, and CTCG), the same laboratory tests used for control group were repeated. The following conception rates (CR) were observed for each batch: B1 = 48.9% (44/90); B2 = 44.2% (23/52); B3 = 55.5% (40/72); B4 = 43.2% (51/118); (p < 0.10). In the lab, B3 presented higher (p ≤ 0.05) progressive motility (PM) than B4 after thawing (control group) and after all sperm challenges (TCG, CCG, and CTCG). However, despite B3 and B4 having demonstrated a similar percentage of plasma membrane integrity (PMI) to the control group (B3 = 66.7 ± 1.3 and B4 = 65.2 ± 3.3), B3 demonstrated higher (P ≤ 0.05) percentage of PMI (37.2 ± 2.5) than B4 (26.7 ± 3.3) after passing through the most stressing in vitro challenge (CTCG). The semen batch presenting the highest resistance to in vitro challenges was the one that presented a trend for higher in vivo fertility, suggesting that submitting semen samples to laboratory challenges may be an interesting alternative for selecting batches with greater field fertility.(AU)

O objetivo deste estudo foi estressar células espermáticas em diferentes desafios laboratoriais e comparar os resultados in vitro com a fertilidade in vivo do sêmen. Quatro partidas de um mesmo touro Brangus foram utilizadas em um programa de IATF de 332 vacas Brangus. Cada partida foi submetida ao seguinte procedimento: a amostra de sêmen foi descongelada a 36°C por 30 segundos (grupo controle). Foram avaliados parâmetros de motilidade espermática (CASA), integridade da membrana plasmática (PMI), morfologia e concentração espermática. Em seguida, uma alíquota da amostra descongelada foi incubada em banho-maria a 45°C durante 40 minutos (grupo de desafio térmico, TCG) e outra alíquota foi centrifugada a 500 xg (gradiente de Percoll 45%/90%) durante 15 min (grupo desafio de centrifugação, CCG). Uma aliquota do sêmen centrifugado foi ainda submetida ao desafio térmico, sendo incubado a 45°C durante 40 min (grupo de desafio térmico + centrifugação, CTCG). No final de cada desafio (CCG, TCG e CTCG), os mesmos testes laboratoriais utilizados para o grupo de controle foram realizados. A seguinte taxa de concepção (CR) foi observada para cada partida (B): B1 = 48,9% (44/90), B2 = 44,2% (23/52), B3 = 55,5% (40/72) e B4 = 43,2% (51/118); (P < 0,10). No laboratório, B3 apresentou maior (P ≤ 0,05) motilidade progressiva (PM) do que B4 logo após o descongelamento (grupo controle) e após todos os desafios laboratoriais (TCG, CCG e CTCG). Porém, apesar de B3 e B4 demonstrarem similar porcentagem de PMI no grupo controle (B3 = 66,7 ± 1,3 e B4 = 65,2 ± 3,3), B3 apresentou maior (P ≤ 0,05) PMI (37,2 ± 2,5%) do que B4 (26,7 ± 3,3%) após passar pelo maior desafio laboratorial (CTCG). A partida seminal que in vitro apresentou maior resistência aos desafios laboratoriais foi a mesma que apresentou tendência para maior fertilidade in vivo. Assim, sugere-se que submeter amostras seminais a desafios laboratoriais pode ser uma alternativa interessante para selecionar partidas com maior fertilidade a campo.(AU)

Assessment of different in vitro sperm challenges and in vivo fertility of bovine semen batches / Avaliação de diferentes desafios espermáticos in vitro e da fertilidade in vivo de partidas de sêmen bovino

The aim of this work was to submit sperm cells to different laboratory challenges and to compare in vitro results with in vivo semen fertility. Four different batches from the same Brangus bull were used in a timed-AI program of 332 Brangus cows. Each batch (B) was submitted to the following procedure: semen sample was thawed at 36°C for 30 seconds (control). Sperm motility parameters, plasma membrane integrity, sperm morphology, and concentration were assessed. Then, an aliquot of thawed sample was incubated in a water bath at 45°C for 40 min (thermal challenge group; TCG) and another aliquot was centrifuged at 500 xg (Percoll gradient 45%/90%) for 15 min (centrifugation challenge group; CCG). Centrifuged semen was also submitted to another thermal challenge, being incubated (water bath) at 45°C for 40 min (centrifugation + thermal challenge group; CTCG). At the end of each challenge (CCG, TCG, and CTCG), the same laboratory tests used for control group were repeated. The following conception rates (CR) were observed for each batch: B1 = 48.9% (44/90); B2 = 44.2% (23/52); B3 = 55.5% (40/72); B4 = 43.2% (51/118); (p < 0.10). In the lab, B3 presented higher (p ≤ 0.05) progressive motility (PM) than B4 after thawing (control group) and after all sperm challenges (TCG, CCG, and CTCG). However, despite B3 and B4 having demonstrated a similar percentage of plasma membrane integrity (PMI) to the control group (B3 = 66.7 ± 1.3 and B4 = 65.2 ± 3.3), B3 demonstrated higher (P ≤ 0.05) percentage of PMI (37.2 ± 2.5) than B4 (26.7 ± 3.3) after passing through the most stressing in vitro challenge (CTCG). The semen batch presenting the highest resistance to in vitro challenges was the one that presented a trend for higher in vivo fertility, suggesting that submitting semen samples to laboratory challenges may be an interesting alternative for selecting batches with greater field fertility.(AU)

O objetivo deste estudo foi estressar células espermáticas em diferentes desafios laboratoriais e comparar os resultados in vitro com a fertilidade in vivo do sêmen. Quatro partidas de um mesmo touro Brangus foram utilizadas em um programa de IATF de 332 vacas Brangus. Cada partida foi submetida ao seguinte procedimento: a amostra de sêmen foi descongelada a 36°C por 30 segundos (grupo controle). Foram avaliados parâmetros de motilidade espermática (CASA), integridade da membrana plasmática (PMI), morfologia e concentração espermática. Em seguida, uma alíquota da amostra descongelada foi incubada em banho-maria a 45°C durante 40 minutos (grupo de desafio térmico, TCG) e outra alíquota foi centrifugada a 500 xg (gradiente de Percoll 45%/90%) durante 15 min (grupo desafio de centrifugação, CCG). Uma aliquota do sêmen centrifugado foi ainda submetida ao desafio térmico, sendo incubado a 45°C durante 40 min (grupo de desafio térmico + centrifugação, CTCG). No final de cada desafio (CCG, TCG e CTCG), os mesmos testes laboratoriais utilizados para o grupo de controle foram realizados. A seguinte taxa de concepção (CR) foi observada para cada partida (B): B1 = 48,9% (44/90), B2 = 44,2% (23/52), B3 = 55,5% (40/72) e B4 = 43,2% (51/118); (P < 0,10). No laboratório, B3 apresentou maior (P ≤ 0,05) motilidade progressiva (PM) do que B4 logo após o descongelamento (grupo controle) e após todos os desafios laboratoriais (TCG, CCG e CTCG). Porém, apesar de B3 e B4 demonstrarem similar porcentagem de PMI no grupo controle (B3 = 66,7 ± 1,3 e B4 = 65,2 ± 3,3), B3 apresentou maior (P ≤ 0,05) PMI (37,2 ± 2,5%) do que B4 (26,7 ± 3,3%) após passar pelo maior desafio laboratorial (CTCG). A partida seminal que in vitro apresentou maior resistência aos desafios laboratoriais foi a mesma que apresentou tendência para maior fertilidade in vivo. Assim, sugere-se que submeter amostras seminais a desafios laboratoriais pode ser uma alternativa interessante para selecionar partidas com maior fertilidade a campo.(AU)

Comparison of two timed artificial insemination system schemes to synchronize estrus and ovulation in Nellore cattle.

The aim of this study was to evaluate the reproductive performance of 411 Nellore cows (198 nulliparous, 80 primiparous, and 133 multiparous) submitted to the 5dCO-Synch + P4 or 7dEB + P4 systems. The 5dCO-Synch + P4 system consisted of insertion of an intravaginal progesterone (P4) insert and 100 µg of GnRH (intramuscularly [i.m.]) on Day 0. On Day 5, the P4 insert was removed, and two doses of 25 mg of PGF2α (i.m.) were administered 6 hours apart. Cows not detected in estrus until 55 hours after insert removal received 100 µg of GnRH i.m. 17 hours later (i.e., 72 hours after P4 removal). The 7dEB + P4 system consisted of insertion of a P4 insert and 2 mg of estradiol benzoate (i.m.) on Day 0. On Day 7, the P4 insert was removed and 25 mg of PGF2α, 0.6 mg of estradiol cypionate, and 300 IU of eCG were administered i.m. In both systems, artificial insemination (AI) was performed according to estrus detection (i.e., cows detected in estrus until 55 hours after insert removal were inseminated at 55 hours and cows detected in estrus later or those not detected in estrus were inseminated at 72 hours). Estrus-detection risk was greater (P < 0.05) in 7dEB + P4 (80.4%) than 5dCO-Synch + P4 system (36.4%). Progesterone concentration 10 days after AI was greater (P < 0.05) in 7dEB + P4 than 5dCO-Synch + P4 system in primiparous and multiparous but did not differ between systems in nulliparous cows. Pregnancy per AI was greater (P < 0.05) in 7dEB + P4 (49.7%) than 5dCO-Synch + P4 (35.4%) system. Primiparous had lower estrus-detection risk (25.0%), ovulation risk (76.6%), and pregnancy per AI (28.7%) than multiparous or nulliparous cows. In conclusion, reproductive performance was reduced with the 5dCO-Synch + P4 in comparison with the 7dEB + P4 system in Nellore cows. Moreover, the reproductive traits observed for primiparous cows indicate that more attention is required when timed AI programs are started early after calving.

Gonadorelin at the outset and/or end of an ovulation synchronization progesterone estradiol benzoate-based protocol in Nellore females / Gonadorelina no início e/ou no final do protocolo de sincronização da ovulação a base de progesterona e benzoato de estradiol em fêmeas Nelore

This study aimed to evaluate the effects of gonadorelin (GnRH), used both at the outset of a timed artificial insemination (TAI) protocol to synchronize follicular wave recruitment and at the end to synchronize ovulation, on the conception rate (CR) in Nellore cows. The experiment was conducted on two beef cattle farms in the Vale do Araguaia, MT. The body condition score (BCS) evaluation and ultrasound examination to determine ovarian status [follicle diameter < 10 mm, ≥ 10 mm or presence of corpus luteum (CL)] were performed at the beginning (Day 0) of the TAI protocol. Multiparous cows (n = 494) were subjected to the following protocol: Day 0 insertion of intravaginal progesterone device (P4 DIB®, MSD) previously used for 8 or 16 days and IM administration of 2.0 mg of estradiol benzoate (EB, Gonadiol®, MSD); Day 8 P4 device withdrawal, IM injection of 300 IU of equine chorionic gonadotropin (eCG, Folligon®, MSD), 1.0 mg of estradiol cypionate (ECP®, Zoetis) and 0.265 mg of Sodium cloprostenol (PGF2α, Ciosin®, MSD); Day 10 TAI, performed by a single inseminator. Animals were randomly assigned to one of four groups: control (n = 126), GnRH D0 (n = 123), GnRH D10 (n = 123) and GnRH D0 + D10 (n = 122). Animals treated with GnRH received 50 mcg of gonadorelin (GnRH, Cystorelin®, Merial). Pregnancy was diagnosed by ultrasound 39 ± 10 days after TAI. Data were analyzed using the GLIMMIX procedure of SAS program (P < 0.05). The overall CR was 42.71%. Effect of treatment was not detected (P = 0.2482) on CR, which was 36.89% ± 0.19 (47/126) for the control group, 46.08% ± 0.19 (56/123) for GnRH D0, 48.30% ± 0.18 (61/123) for GnRH D10 and 38.48% ± 0.19 (47/122) for GnRH D0 + D10. An effect of farm was detected; the CR was 47.32% ± 0.13 at Farm A and was 38.24% ± 0.13 at Farm B (P = 0.0249). No effects of the interaction between farm and treatment were observed (P = 0.7662), nor of those among ovarian condition and treatment (P = 0.1225) on CR.[...](AU)

Objetivou-se avaliar os efeitos da gonadorelina (GnRH) utilizada para sincronização da emergência da onda de crescimento folicular e para indução da ovulação sincronizada ou em ambos sobre a taxa de concepção (TC) de vacas da raça Nelore. O experimento foi realizado em duas fazendas no Vale do Araguaia, MT. A avaliação do escore de condição corporal (ECC) e a ultrassonografia para determinação da condição dos ovários [folículo com diâmetro < 10 mm, ≥ 10 mm ou presença de corpo lúteo (CL)] foram realizadas no início (Dia 0) do protocolo de inseminação artificial em tempo fixo (IATF). Vacas multíparas (n = 494) foram submetidas ao protocolo: Dia 0 inserção do dispositivo intravaginal de progesterona (P4, DIB®, MSD) utilizado previamente por oito ou 16 dias e aplicação IM de 2,0 mg de Benzoato de Estradiol (BE, Gonadiol®, MSD); Dia 8 remoção do dispositivo, aplicação IM de 300 UI de Gonadotrofina Coriônica Equina (eCG, Folligon®, MSD), de 1,0 mg de Cipionato de Estradiol (ECP®, Zoetis) e de 0,265 mg de Cloprostenol Sódico (PGF2α, Ciosin®, MSD); Dia 10 IATF, realizada por um único inseminador. Os animais foram distribuídos aleatoriamente em quatro grupos: controle (n = 126), GnRH D0 (n = 123), GnRH D10 (n = 123) e GnRH D0 + D10 (n = 122), sendo que os animais tratados com GnRH receberam 50 mcg de gonadorelina (GnRH, Cystorelin®, Merial). O diagnóstico de gestação foi realizado por ultrassonografia 39 ± 10 dias após a IATF. As variáveis foram analisadas pelo procedimento GLIMMIX do programa SAS (P < 0,05). Verificou-se uma TC geral de 42,71%. Não foi detectado efeito dos tratamentos sobre a TC (P = 0,2482), que foi de 36,89% ± 0,19 (47/126) para o grupo controle, 46,08% ± 0,19 (56/123) para GnRH D0, 48,30% ± 0,18 (61/123) para GnRH D10 e de 38,48% ± 0,19 (47/122) para GnRH D0 + D10. Observou-se efeito da variável fazenda, sendo que na Fazenda A a TC foi de 47,32% ± 0,13 e na Fazenda B de 38,24% ± 0,13 (P = 0,0249).[...](AU)

Gonadorelin at the outset and/or end of an ovulation synchronization progesterone estradiol benzoate-based protocol in Nellore females / Gonadorelina no início e/ou no final do protocolo de sincronização da ovulação a base de progesterona e benzoato de estradiol em fêmeas Nelore

This study aimed to evaluate the effects of gonadorelin (GnRH), used both at the outset of a timed artificial insemination (TAI) protocol to synchronize follicular wave recruitment and at the end to synchronize ovulation, on the conception rate (CR) in Nellore cows. The experiment was conducted on two beef cattle farms in the Vale do Araguaia, MT. The body condition score (BCS) evaluation and ultrasound examination to determine ovarian status [follicle diameter < 10 mm, ≥ 10 mm or presence of corpus luteum (CL)] were performed at the beginning (Day 0) of the TAI protocol. Multiparous cows (n = 494) were subjected to the following protocol: Day 0 insertion of intravaginal progesterone device (P4 DIB®, MSD) previously used for 8 or 16 days and IM administration of 2.0 mg of estradiol benzoate (EB, Gonadiol®, MSD); Day 8 P4 device withdrawal, IM injection of 300 IU of equine chorionic gonadotropin (eCG, Folligon®, MSD), 1.0 mg of estradiol cypionate (ECP®, Zoetis) and 0.265 mg of Sodium cloprostenol (PGF2α, Ciosin®, MSD); Day 10 TAI, performed by a single inseminator. Animals were randomly assigned to one of four groups: control (n = 126), GnRH D0 (n = 123), GnRH D10 (n = 123) and GnRH D0 + D10 (n = 122). Animals treated with GnRH received 50 mcg of gonadorelin (GnRH, Cystorelin®, Merial). Pregnancy was diagnosed by ultrasound 39 ± 10 days after TAI. Data were analyzed using the GLIMMIX procedure of SAS program (P < 0.05). The overall CR was 42.71%. Effect of treatment was not detected (P = 0.2482) on CR, which was 36.89% ± 0.19 (47/126) for the control group, 46.08% ± 0.19 (56/123) for GnRH D0, 48.30% ± 0.18 (61/123) for GnRH D10 and 38.48% ± 0.19 (47/122) for GnRH D0 + D10. An effect of farm was detected; the CR was 47.32% ± 0.13 at Farm A and was 38.24% ± 0.13 at Farm B (P = 0.0249). No effects of the interaction between farm and treatment were observed (P = 0.7662), nor of those among ovarian condition and treatment (P = 0.1225) on CR.[...]

Objetivou-se avaliar os efeitos da gonadorelina (GnRH) utilizada para sincronização da emergência da onda de crescimento folicular e para indução da ovulação sincronizada ou em ambos sobre a taxa de concepção (TC) de vacas da raça Nelore. O experimento foi realizado em duas fazendas no Vale do Araguaia, MT. A avaliação do escore de condição corporal (ECC) e a ultrassonografia para determinação da condição dos ovários [folículo com diâmetro < 10 mm, ≥ 10 mm ou presença de corpo lúteo (CL)] foram realizadas no início (Dia 0) do protocolo de inseminação artificial em tempo fixo (IATF). Vacas multíparas (n = 494) foram submetidas ao protocolo: Dia 0 inserção do dispositivo intravaginal de progesterona (P4, DIB®, MSD) utilizado previamente por oito ou 16 dias e aplicação IM de 2,0 mg de Benzoato de Estradiol (BE, Gonadiol®, MSD); Dia 8 remoção do dispositivo, aplicação IM de 300 UI de Gonadotrofina Coriônica Equina (eCG, Folligon®, MSD), de 1,0 mg de Cipionato de Estradiol (ECP®, Zoetis) e de 0,265 mg de Cloprostenol Sódico (PGF2α, Ciosin®, MSD); Dia 10 IATF, realizada por um único inseminador. Os animais foram distribuídos aleatoriamente em quatro grupos: controle (n = 126), GnRH D0 (n = 123), GnRH D10 (n = 123) e GnRH D0 + D10 (n = 122), sendo que os animais tratados com GnRH receberam 50 mcg de gonadorelina (GnRH, Cystorelin®, Merial). O diagnóstico de gestação foi realizado por ultrassonografia 39 ± 10 dias após a IATF. As variáveis foram analisadas pelo procedimento GLIMMIX do programa SAS (P < 0,05). Verificou-se uma TC geral de 42,71%. Não foi detectado efeito dos tratamentos sobre a TC (P = 0,2482), que foi de 36,89% ± 0,19 (47/126) para o grupo controle, 46,08% ± 0,19 (56/123) para GnRH D0, 48,30% ± 0,18 (61/123) para GnRH D10 e de 38,48% ± 0,19 (47/122) para GnRH D0 + D10. Observou-se efeito da variável fazenda, sendo que na Fazenda A a TC foi de 47,32% ± 0,13 e na Fazenda B de 38,24% ± 0,13 (P = 0,0249).[...]

Effect of GnRH or estradiol benzoate on reproductive traits during a Heatsynch protocol in dairy cows

Background: Milk production of cows is closely correlated with its reproductive efficiency. One of the several factors influencing the dairy efficiency is the decline in fertility of the cows/heifers. Use of hormonal protocol are often used to improve the fertility of the recipients. Several programs are available to inseminate dairy cows, with variation in the use of different types of hormones, time of use and range of duration period, as well as the time of AI. The objective of this study was to evaluate the efficiency of follicular wave emergence induction of estradiol benzoate in comparison to GnRH in a Heatsynch protocol and its influence on reproductive parameters. Materials, Methods & Results: In this study were used primiparous and multiparous Holstein cows (n = 325). Animals were divided randomly into two different treatments according with the hormone used to induce follicular wave emergence (D0). The GnRH group (n = 167), was given 25 mg, while in the EB group (n = 158) was used 2 mg. At same day, were inserted, a controlled internal drug-releasing containing 1.9 g of progesterone CIDR®. On day 7, CIDR was removed and cows were given 25 mg luteinizing hormone followed by an injection of 1 mg Inducer Ovulation at day 8. Cows were then observed for signs of estrus for at least two hours (twice daily at 7 am and 6 pm) for three days following CIDR® removal. Cows [...]

Effect of GnRH or estradiol benzoate on reproductive traits during a Heatsynch protocol in dairy cows

Background: Milk production of cows is closely correlated with its reproductive efficiency. One of the several factors influencing the dairy efficiency is the decline in fertility of the cows/heifers. Use of hormonal protocol are often used to improve the fertility of the recipients. Several programs are available to inseminate dairy cows, with variation in the use of different types of hormones, time of use and range of duration period, as well as the time of AI. The objective of this study was to evaluate the efficiency of follicular wave emergence induction of estradiol benzoate in comparison to GnRH in a Heatsynch protocol and its influence on reproductive parameters. Materials, Methods & Results: In this study were used primiparous and multiparous Holstein cows (n = 325). Animals were divided randomly into two different treatments according with the hormone used to induce follicular wave emergence (D0). The GnRH group (n = 167), was given 25 mg, while in the EB group (n = 158) was used 2 mg. At same day, were inserted, a controlled internal drug-releasing containing 1.9 g of progesterone CIDR®. On day 7, CIDR was removed and cows were given 25 mg luteinizing hormone followed by an injection of 1 mg Inducer Ovulation at day 8. Cows were then observed for signs of estrus for at least two hours (twice daily at 7 am and 6 pm) for three days following CIDR® removal. Cows [...](AU)

Controle farmacológico do ciclo estral / Pharmacologicol control of oestrus cicle

O emprego de hormônios na fêmea suína objetiva a sincronização do estro à puberdade em marrãs e a sincronização do estro para o emprego da técnica da inseminação artificial em tempo fixo. Na sincronização do estro à puberdade, atenção especial deve estar voltada ao manejo da marrã, pois, além de representar de 30 a 40% do plantel de matrizes, vários fatores envolvidos no manejo afetam a vida útil reprodutiva, influenciando,assim, o rebanho como um todo. O presente trabalho vem abordar alguns aspectos relacionados aos hormônios no ciclo estral, com atenção voltada à importância da sincronização do estro, visando, no complexo interativo do manejo reprodutivo, a uma vida útil reprodutiva ideal, fruto do melhor aproveitamento da matriz no plantel e consequente homogeneização da produção.p(AU)

The use of hormones in the swine female, aims the estrus synchronization at puberty in gilts and the estrus synchronization to the technique of artificial insemination at fixed time. Special attention must be given to the puberty estrus synchronization on the gilts management, because, besides representing 30 to 40% of the breeding herd, there are many factors involved that may affect their reproductive lifetime. The presenting article describes some aspects in relation to the hormones in estrous cycle, mainly estrus synchronization that influenced reproductive lifetime, to the better usage of the female management in the breeding herd and finally in direction to the production homogeneity(AU)

Controle farmacológico do ciclo estral / Pharmacologicol control of oestrus cicle

O emprego de hormônios na fêmea suína objetiva a sincronização do estro à puberdade em marrãs e a sincronização do estro para o emprego da técnica da inseminação artificial em tempo fixo. Na sincronização do estro à puberdade, atenção especial deve estar voltada ao manejo da marrã, pois, além de representar de 30 a 40% do plantel de matrizes, vários fatores envolvidos no manejo afetam a vida útil reprodutiva, influenciando,assim, o rebanho como um todo. O presente trabalho vem abordar alguns aspectos relacionados aos hormônios no ciclo estral, com atenção voltada à importância da sincronização do estro, visando, no complexo interativo do manejo reprodutivo, a uma vida útil reprodutiva ideal, fruto do melhor aproveitamento da matriz no plantel e consequente homogeneização da produção.p

The use of hormones in the swine female, aims the estrus synchronization at puberty in gilts and the estrus synchronization to the technique of artificial insemination at fixed time. Special attention must be given to the puberty estrus synchronization on the gilts management, because, besides representing 30 to 40% of the breeding herd, there are many factors involved that may affect their reproductive lifetime. The presenting article describes some aspects in relation to the hormones in estrous cycle, mainly estrus synchronization that influenced reproductive lifetime, to the better usage of the female management in the breeding herd and finally in direction to the production homogeneity