Sincronização da ovulação em fêmeas suínas submetidas ao desmame precoce

Verificou-se a eficiência de protocolos para sincronizar a ovulação em porcas desmamadas precocemente. Trinta porcas com média de 4,4± 2,0 partos e estádio de lactação de 14,8± 0,7 dias foram distribuídas em três grupos de 10 animais: 1- nenhum tratamento hormonal; 2- 1000 UI de PMSG, via intramuscular (IM), 48h pós-desmame e 0,25mg de GnRH, IM, 72h após a aplicação do PMSG; 3- 1000 UI de PMSG, IM, 48h pós-desmame e 500 UI de hCG, IM, 72h após o PMSG. O momento da ovulação foi detectado por ultra-sonografia transretal. A taxa de sincronização (ovulação até 48h após aplicação de hCG ou GnRH) dos grupos 2 e 3 (94,7%) foi maior (P<0,01) que no grupo controle (40%). Com o uso dos protocolos de sincronização de ovulação, as fêmeas tratadas apresentaram, em relação ao grupo controle, tendência de maior taxa de prenhez (95% vs. 70%; P<0,10) e similares intervalo do desmame ao estro (96,5± 3,0 vs. 130,2± 31,4h) e número de leitões nascidos vivos por fêmea gestante no primeiro cio pós-desmame (10,9± 0,8 vs. 12,0± 0,9). Dessa maneira, os protocolos de sincronização usados neste estudo foram eficientes em sincronizar a ovulação, e podem viabilizar o uso da inseminação artificial em horários predeterminados.

Mês de parição, condição corporal e resposta ao protocolo de inseminação artificial em tempo fixo em vacas de corte primíparas

No experimento I, foi avaliada a alteração da condição corporal (CC) pré e pós-parto em 155 novilhas inseminadas para parir de setembro a dezembro. A CC foi avaliada mensalmente no pré e pós-parto, de junho a fevereiro. No experimento II, 538 vacas primíparas foram sincronizadas com o protocolo de inseminação artificial em tempo fixo (IATF) que usou estradiol junto ao dispositivo intravaginal de progesterona (CIDR®). As taxas de ciclicidade, sincronização e concepção foram avaliadas por ultra-som. No experimento I, os animais que pariram primeiro tiveram maior (P<0,001) redução na CC pós-parto. No experimento II, foi observado maior CC (P<0,0001) nos animais com menor número de dias pós-parto, maior (P<0,05) taxa de sincronização nas vacas de melhor CC e aumento (P<0,0001) na taxa de concepção proporcional ao aumento na CC (incremento médio na concepção de seis pontos percentuais para cada 0,25 ponto na CC). Não se deve antecipar a parição de novilhas de corte quando se pretende realizar IATF no início da estação de monta subseqüente.

Indução à ovulação pelo uso de LHRH análogo e fertilização artificial em rã-touro (Rana catesbeiana)

Este trabalho teve por objetivo aperfeiçoar a técnica de reprodução induzida existente para rã-touro, com o intuito de aumentar a taxa de fecundidade e viabilizar seu uso pelo produtor. As doses hormonais para a indução da ovulação e espermiação seguiram as propostas de FALCON e CULLEY (1995) e ALONSO (1997); entretanto, a técnica de fertilização artificial foi adaptada da metodologia para reprodução artificial de peixes com ovos não-aderentes (WOYNAROVICH e HORVÁTH, 1983). A técnica proposta apresenta as seguintes etapas: I) sincronização da ovulação e da espermiação, por meio de hormônio liberador de gonadotropina ((Des-Gli10, D-His(Bzl)6, Pro-NHEt9)-LHRH)); II) extração dos óvulos de cada fêmea (1 a 2 minutos); III) fertilização dos óvulos (2 minutos) com líquido espermático diluído em 100 mL de água; IV) hidratação dos ovos em 10 a 20 litros de água; e V) incubação dos ovos em quadros de tela de 1x 0,70 m, com malha de 1 mm. As taxas de fertilização obtidas com as modificações propostas foram superiores a 60%. Ressalta-se ainda que a técnica propiciou a obtenção, a partir de um mesmo animal, de várias desovas, sendo que cada fêmea pode ovular em intervalos de, aproximadamente, 45 dias.

Progesterone concentrations, exogenous equine chorionic gonadotropin, and timing of prostaglandin F-2 alpha treatment affect fertility in postpuberal Nelore heifers

Two experiments were performed to test the hypothesis that elevated progesterone concentrations impair pregnancy rate to timed artificial insemination (TAI) in postpuberal Nelore heifers. In Experiment 1, postpuberal Nelore heifers (n = 398) received 2 mg estradiol benzoate (EB) and either a new progesterone-releasing intravaginal device containing 1.9 g of progesterone (CIDR) (first use) or a CIDR previously used for 9 d (second use) or for 18 d (third use) on Day 0, 12.5 mg prostaglandin F-2 alpha (PGF(2 alpha)) on Day 7, 0.5 mg estradiol cypionate (ECP) and CIDR withdrawal on Day 9, and TAI on Day 11. Largest ovarian follicle diameter was determined on Day 11. The third-use CIDR treatment increased largest ovarian follicle diameter and pregnancy rate. Conception to TAI was reduced in heifers with smaller follicles in the first- and second-use CIDR treatments, but not in the third-use CID treatment. In Experiment 2, postpuberal Nelore heifers received the synchronization treatment described in Experiment 1 or received 12.5 mg PGF2. on Day 9 rather than Day 7. In addition, 50% of heifers received 300 IU equine chorionic gonadotropin (eCG) on Day 9. Heifers were either TAI (Experiment 2a; n = 199) or Al after detection of estrus (Experiment 2b; n = 125 of 202). In Experiment 2a, treatment with cCG increased pregnancy rate to TAI in heifers that received PGF2. on Day 9 but not on Day 7 and in heifers that received a first-use CIDR but not in heifers that received a third-use CIDR. Treatments did not influence reproductive performance in Experiment 2b. In summary, pregnancy rate to TAI in postpuberal Nelore heifers was optimized when lower concentrations of cxogcnous progesterone were administered, and eCG treatment was beneficial in heifers expected to have greater progesterone concentrations. (C) 2009 Elsevier B.V. All rights reserved.

Elevated progesterone concentrations enhance prostaglandin F-2 alpha synthesis in dairy cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Strategic supplementation of calcium salts of polyunsaturated fatty acids to enhance reproductive performance of Bos indicus beef cows

Five experiments evaluated the effects of supplemental Ca salts of PUFA on reproductive function of Bos indicus beef cows. In Exp. 1, nonlactating and multiparous grazing cows (n = 51) were assigned to receive (as-fed basis) 0.1 kg of a protein-mineral mix + 0.1 kg of ground corn per cow/d, in addition to 0.1 kg per cow/d of 1) Ca salts of PUFA (PF), 2) Ca salts of SFA (SF), or 3) kaolin (control). Treatments were offered from d 0 to 20 of the estrous cycle. No treatment effects were detected on serum progesterone concentrations (P = 0.83), day of luteolysis (P = 0.86), or incidence of short cycles (P = 0.84). In Exp. 2, nonlactating and multiparous grazing cows (n = 43) were assigned to receive PF, SF, or control from d 0 to 8 of the estrous cycle. on d 6, all cows received (intramuscularly) 25 mg of PGF(2 alpha). No treatment effects were detected on serum progesterone concentrations on d 6 (P = 0.37), and incidence (P = 0.67) or estimated time of luteolysis (P = 0.44). In Exp. 3, twenty-seven lactating and multiparous grazing cows, approximately 30 to 40 d postpartum, were assigned to receive PF or control for 10 d beginning at the first postpartum ovulation. No treatment effects were detected (P = 0.85) on incidence of short cycles. In Exp. 4, lactating and multiparous grazing cows (n = 1,454), approximately 40 to 60 d postpartum, were assigned to receive 1 of the 7 treatments for 28 d after timed AI (TAI; d 0): 1) control from d 0 to 28, 2) SF from d 0 to 14 and then control, 3) PF from d 0 to 14 and then control, 4) SF from d 0 to 21 and then control, 5) PF from d 0 to 21 and then control, 6) SF from d 0 to 28, and 7) PF from d 0 to 28. Cows receiving PF for more than 21 d after TAI had greater (P < 0.01) pregnancy to TAI compared with all other treatments combined (50.4 vs. 42.4%, respectively). In Exp. 5, lactating and multiparous grazing cows (n = 501), approximately 40 to 60 d postpartum, were assigned to receive 1 of the 4 treatments for 21 d after TAI (d 0): 1) PF from d 0 to 14 and then control, 2) control from d 0 to 6 and then PF, 3) control from d 0 to 13 and then PF, and 4) PF from d 0 to 21. Cows receiving PF after d 14 of the experiment had greater (P = 0.02) pregnancy to TAI compared with cows not receiving PF during the same period (46.8 vs. 33.1%, respectively). In summary, supplemental Ca salts of PUFA during the expected time of luteolysis increased pregnancy to TAI in beef cows.

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

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Intravaginal progesterone device and/or temporary weaning on reproductive performance of anestrous crossbred Angus x Nelore cows

The objective of this experiment was to evaluate effects of treatments with intravaginal progesterone (N) device and/or 48 h temporary weaning (TW) on reproductive performance of postpartum anestrous crossbred Angus x Nelore cows, throughout the breeding season (BS). Anestrous cows (n = 296; 53 5 DPP, body condition score between 2.5 and 3.5, on a 1-5 scale) were assigned randomly to four treatments (2 x 2 factorial design): (1) Control Group (no treatment; n = 73); (2) TW Group (48 h TW beginning on day 0 of BS; n = 70); (3) P4 Group (Intravaginal P4 device between days -7 and 0 of BS; n = 73); and (4) P4+TW Group (Intravaginal P4 device between days -7 and 0 of BS followed by 48h TW; n=70). on day 0 of BS (when P4 devices were removed and TW was initiated), cows had their ovaries evaluated by ultrasonography aiming to evaluate size of the largest follicle. Signs of behavioral estrus were observed twice a day (morning and evening), between days 0 and 25 of BS, and cows observed in estrus were inseminated 12 h later. Between days 26 and 80 of BS, cows were submitted to natural service. Pregnancy diagnosis was conducted by transrectal ultrasonography on days 32 and 53 (pregnancies by AI) and 114 (pregnancies by natural service). Rates of detection of estrus during the first 3 days and within 25 days of BS were greater in cows receiving TW (45.0% compared with 9.6% and 50.0% compared with 29.5%, respectively; P < 0.01). Conception rate in cows inseminated in the first 3 days of BS was greater in cows treated with P4 (54.8% compared with 11.1 %; P < 0.01). Combining P4+TW increased pregnancy rate in the first 3 days (Control: 1.4%, TW: 4.3%, P4: 8.2% and P4+TW: 24.3%; P < 0.01) and in 25 days of BS (Control: 10.9%, TW: 7.1%, P4: 13.7% and P4+TW: 28.6%; P < 0.05). Pregnancy rate at the end of BS did not differ among treatment groups. In conclusion, TW alone increased estrous behavior whereas P4 alone benefited conception. Combining P4 with TW improved pregnancy rate with direct benefits to behavioral estrus and conception. (c) 2008 Elsevier B.V. All rights reserved.

Comparison of progesterone-based protocols with gonadotropin-releasing hormone or estradiol benzoate for timed artificial insemination or embryo transfer in lactating dairy cows

The objective was to compare two protocols for synchronizing ovulation in lactating Holstein cows submitted to timed AI (TAI) or timed ET (TET). Within each farm (n = 8), cows (n = 883; mean +/- SEM 166.24 +/- 3.27 d postpartum, yielding 36.8 +/- 0.34 kg of milk/d) were randomly assigned to receive either: 1) an intravaginal progesterone insert (CIDR (R)) with 1.9 g of progesterone + GnRH on Day -10, CIDR (R) withdrawal + PGF2 alpha on Day -3, and 1 mg estradiol cypionate on Day -2 (treatment GP-P-E; n(TAI) = 180; n(TET) = 260); or 2) a CIDR (R) insert + 2 mg estradiol benzoate on Day -10, PGF2 alpha on Day -3, CIDR (R) withdrawal + 1 mg estradiol cypionate on Day -2 (treatment EP-P-E; n(TAI) = 174; n(TET) = 269). Cows were subsequently randomly assigned to receive either TAT on Day 0 or TET on Day 7. Serum progesterone concentration on Day -3 was greater in GP-P-E than in EP-P-E (2.89 +/- 0.15 vs 2.29 +/- 0.15 ng/mL; P < 0.01), with no significant effect of group on serum progesterone on Day 7. Compared to cows submitted to TAI, those submitted to TET had greater pregnancy rates on Day 28 (44.0% [233/5291 vs 29.7% [105/354]; p < 0.001) and on Day 60 (37.6% [199/529] vs 26.5 [94/354]; P < 0.001). However, there were no effects of treatments (GP-P-E vs EP-P-E; P > 0.10) on synchronization (87.0% [383/440] vs 85.3% [378/443]), conception (TAI: 35.3% [55/156] vs 33.8% [50/148]; TET: 50.7% [115/227] vs 51.3% [118/230]) and pregnancy rates on Days 28 (TAT: 30.5% [55/180] vs 28.7% 150/174]; TET: 44.2% [115/260] vs 43.9% [118/2691) and 60 (TAI: 27.2% [49/80] vs 25.9% [45/174]; TET: 38.8% [101/260] vs 36.4% [98/269]). In conclusion, GP-P-E increased serum progesterone concentrations on Day -3, but rates of synchronization, conception, and pregnancy were not significantly different between cows submitted to GP-P-E and EP-P-E protocols, regardless of whether they were inseminated or received an embryo. (c) 2011 Elsevier B.V. All rights reserved.

Effect of progesterone and/or estradiol treatments prior to induction of ovulation on subsequent luteal lifespan in anestrous Nelore cows

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Strategies to improve fertility in postpartum multiparous Bos indicus cows submitted to a fixed-time insemination protocol with gonadotropin-releasing hormone and prostaglandin F-2 alpha

In Exp. 1, we evaluated the effects of 2 lengths of progesterone exposure [CIDR (controlled intravaginal drug release); 7 vs. 14 d] before a modified CO-Synch protocol [50.0-mu g injection of GnRH 6.5 d before a 25.0-mg injection of PGF(2 alpha) followed by another injection of GnRH and fixed-time AI (TAI) 2 d after PGF(2 alpha)], with or without temporary weaning (TW) before GnRH treatments, on fertility of suckled multiparous Bos indicus cows (n = 283) and on calf performance. Timed AI pregnancy rates for cows receiving 7 d CIDR + TW, 7 d CIDR, 14 d CIDR + TW, and 14 d CIDR were 53, 47, 46, and 41%, respectively (P > 0.10). Calves submitted to two 48-h TW 6 d apart had decreased mean BW at 240 d (187.9 +/- 2.7 vs. 195.5 +/- 2.7 kg; P < 0.05), but BW at 420 d was not affected by TW (240.1 +/- 5.1 kg). In Exp. 2, we evaluated the effect of no treatment and treatment with or without a CIDR insert between GnRH and PGF(2 alpha) treatments of a modified CO-Synch protocol on pregnancy rate to TAI, and throughout a 90-d breeding season in suckled multiparous Bos indicus cows (n = 453). The inclusion of a CIDR between first GnRH and PGF(2 alpha) treatments of a modified CO-Synch protocol did not improve pregnancy rate (29 and 33% for cows receiving CO-Synch + CIDR and CO-Synch protocol, respectively), and cycling cows had poorer TAI pregnancy rates than anestrous cows treated with either synchronization protocol (21.7 vs. 40.7%; P < 0.05). However, regardless of treatment with CIDR, cows submitted to TAI protocol had greater (P < 0.05) pregnancy rates at 30 (54.8 vs. 11.2%), 60 (72.1 vs. 38.8%), and 90 d (82.0 vs. 57.9%) of breeding season than untreated cows.

Effects of temperament on pregnancy rates to fixed-timed AI in Bos indicus beef cows

The objective of the present experiment was to assess the effects of temperament on pregnancy rates to fixed-time AI (FTAI) in Bos indicus beef cows. A total of 761 multiparous lactating Nelore cows, originated from 4 different commercial cow-calf ranches, were evaluated for BCS and temperament at the time of FTAI (day 0). Temperament was assessed by chute score and exit velocity. Further, individual exit score was calculated by dividing exit velocity results into quintiles and assigning cows with a score from 1 to 5 (exit score: 1 = slowest cows; 5 = fastest cow). Temperament scores were calculated by averaging cow chute score and exit score. Cows were also classified for temperament type according to temperament score (<= 3 = adequate temperament, >3 = excitable temperament). Pregnancy status was verified by detecting a viable conceptus with rectal ultrasonography approximately 40 days after FTAI. Chute score, exit velocity, and temperament score were not correlated to BCS (P>0.31). Hence, BCS did not differ (P=0.30) according to temperament type (4.13 vs. 4.09 for cows with excitable and adequate temperament, respectively; SEM = 0.070). Pregnancy rates to FTAI tended to be negatively affected by temperament score (P=0.08), whereas the probability of cows becoming pregnant to FTAI was negatively associated with temperament score (linear effect, P<0.01). Accordingly, pregnancy rates were reduced (P=0.05) in cows with excitable temperament compared to cows with adequate temperament (35.3 vs. 42.8% of pregnant cows/total cows, respectively; SEM = 2.85). Pregnancy rates to FTAI were not affected by chute score (P=0.25), although the probability of cows becoming pregnant to FTAI tended to be negatively associated with chute score (linear effect, P=0.07). Pregnancy rates to FTAI were negatively affected by exit score (P=0.05), and the probability of cows becoming pregnant to FTAI was negatively associated with exit score and with actual exit velocity (linear effects, P<0.01). Results from this experiment indicate that excitable temperament is detrimental to pregnancy rates of B. indicus cows assigned to an estrus synchronization + FTAI protocol. Published by Elsevier B.V.

Managing the dominant follicle in lactating dairy cows

Reproductive efficiency is not optimal in high-producing dairy cows. Although many aspects of ovarian follicular growth in cows are similar to those observed in heifers, there are numerous specific differences in follicular development that may be linked with changes in reproductive physiology in high-producing lactating dairy cows. These include: I) reduced circulating estradiol (E2) concentrations near estrus, 2) ovulation of follicles that are larger than the optimal size, 3) increased double ovulation and twinning, and 4) increased incidence of anovulation with a distinctive pattern of follicle growth in anovular dairy cows. The first three changes become more dramatic as milk production increases, although anovulation has not generally been associated with level of milk production. To overcome reproductive inefficiencies in dairy cows, reproductive management programs have been developed to synchronize ovulation and enable the use of timed AI in lactating dairy cows. Effective regulation of the CL, follicles, and hormonal environment during each part of the protocol is critical for optimizing these programs. This review discusses the distinct aspects of follicular development in lactating dairy cows and the methodologies that have been utilized in the past two decades in order to manage the dominant follicle during synchronization of ovulation and timed AI programs. (C) 2011 Published by Elsevier B.V.

Efeito da frequência de amamentação sobre a taxa de ovulação após tratamento com desmame temporário + GnRH, sobre a incidência de luteólise prematura no primeiro ciclo estral pós-parto e sobre o desempenho da progênie de vacas Nelore

Avaliou-se o efeito da restrição na frequência de amamentação sobre o diâmetro folicular no dia 0 (DFOL), sobre a taxa de ovulação (TO), e sobre a incidência de luteólise prematura no primeiro ciclo estral pós-parto (ILP) de vacas Nelore multíparas, em anestro, submetidas à amamentação ad libitum (controle; n= 115) ou amamentação uma vez ao dia (restrito; n= 109), entre os dias -14 e 9 do experimento, e estudou-se o efeito desses tratamentos sobre o peso à desmama da progênie dessas vacas. Induziu-se ovulação com remoção de bezerros entre os dias -2 e 0 e aplicação de 100μg de GnRH no dia 0. Somente animais que ovularam foram mantidos no experimento (n= 125). A ocorrência de luteólise prematura foi avaliada por meio da dosagem da concentração sérica de progesterona nos dias 5 e 9. A TO não foi influenciada pelos tratamentos (55,8%; P>0,1), e as vacas do tratamento restrito apresentaram maior DFOL (10,90±0,26 vs. 10,18±0,21mm; P<0,05) e menor ILP (21,4% vs. 43,5%; P<0,05). Os bezerros do tratamento controle foram mais pesados (162,32±2,08 vs. 155,91±4,12kg; P<0,05). Conclui-se que a restrição na frequência de amamentação em vacas Nelore reduz a ILP, porém com possível efeito negativo no desenvolvimento dos bezerros.

Induction of double ovulation in mares using deslorelin acetate

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)