RESUMO

The objectives of this experiment were to evaluate the effects of supplementation of Nellore (Bos indicus) cows with ß-carotene + vitamins A + D3 + E + biotin on body condition score (BCS), oestrus, pregnancy, and foetal morphometry. Lactating cows (n = 497) from two herds were balanced for BCS and calving period [early calving (EC); late calving (LC)] and were assigned randomly to: Control (n = 251)-supplementation with a mineral supplement; and SUP (n = 246)-supplementation with the mineral supplement fed to control + ß-carotene (150 mg/day) + vitamin A (40,000 IU/day) + vitamin D3 (5000 IU/day) + vitamin E (300 mg/day) + biotin (20 mg/day). Cows were supplemented from Days -30 to 30 (Day 0 = timed artificial insemination; TAI). Pregnancy was diagnosed 30 days after TAI and foetal crown-rump distance and thoracic diameter were measured at 30 and 77 days of gestation. Cows in the SUP treatment were more likely to have BCS ≥3.0 on Day 0 (63.0 ± 3.1 vs. 60.2 ± 3.1; p < .01) and were more likely to gain BCS from Days -30 to 30 (57.7 ± 3.3 vs. 44.1 ± 3.3%; p < .01). Fewer LC cows in the SUP treatment were detected in oestrus at the time of the first TAI (Control: LC: 75.4 ± 4.4 vs. SUP: LC: 64.0 ± 5.2 vs. Control: EC: 65.3 ± 4.0 vs. SUP: EC: 71.8 ± 3.7; p = .04). There was a tendency for the SUP treatment to increase pregnancy to the first TAI (64.2 ± 3.0 vs. 56.6 ± 3.1%; p = .08). A greater percentage of SUP cows was detected in oestrus at the time of the second TAI (70.1 ± 5.0 vs. 52.3 ± 4.8%; p = .01). The SUP treatment increased pregnancy to the second TAI among LC cows (SUP: LC: 75.9 ± 8.0% vs. Control: LC: 50.0 ± 8.3% vs. Control: EC: 52.0 ± 5.9% vs. SUP: EC: 41.4 ± 6.5%; p = .02). The SUP treatment increased foetal size (crown-rump; p = .04 and thoracic diameter; p < .01) at 30 days of gestation and, despite decreasing crow-rump length at 77 days after the first TAI among EC cows (p < .01), it increased the thoracic diameter at 77 days after the first TAI independent of calving season. Our results support that pregnancy establishment and foetal growth can be improved when grazing Nellore cows are supplemented with ß-carotene and vitamins A + D3 + E + biotin.

Assuntos

Biotina , Suplementos Nutricionais , Estro , Vitamina A , Vitamina E , beta Caroteno , Animais , Bovinos , Feminino , Gravidez , Vitamina A/administração & dosagem , Vitamina A/farmacologia , beta Caroteno/administração & dosagem , beta Caroteno/farmacologia , Vitamina E/administração & dosagem , Vitamina E/farmacologia , Estro/efeitos dos fármacos , Biotina/administração & dosagem , Biotina/farmacologia , Colecalciferol/farmacologia , Colecalciferol/administração & dosagem , Folículo Ovariano/efeitos dos fármacos , Dieta/veterinária , Vitaminas/administração & dosagem , Vitaminas/farmacologia , Ração Animal , Lactação , Feto/efeitos dos fármacos

RESUMO

This study evaluated the efficacy of the administration of different doses of equine chorionic gonadotropin (eCG; 0 IU, 200 IU, or 300 IU) at the time of the progesterone device removal in 2-year-old Nelore (Bos indicus) heifers synchronized for fixed-timed artificial insemination (FTAI). On day 0 (D0), a total of 398 heifers received 2 mg of oestradiol benzoate i.m., 0.53 mg of cloprostenol i.m., and an eight-day previously used (second use) intravaginal device containing 1 g of progesterone (P4). Eight days later (D8), simultaneous with the P4 device removal, 0.5 mg of oestradiol cypionate i.m. and 0.53 mg of cloprostenol i.m. were administered. At the same time, heifers were randomly assigned to receive one of the following treatments: G-0 IU (n = 141; no eCG treatment), G-200 IU (n = 132; treated with 200 IU of eCG), and G-300 IU (n = 125; treated with 300 IU of eCG). FTAI was performed 48 h after the P4 device removal (D10). Ultrasonographic evaluations were performed at D0, D10, and D17. Heifers were scanned to measure the size of the largest follicle (LF), the presence, number, and size of the corpus luteum (CL), and the ovulation rate. Subsequently, at D40, the heifers underwent scanning to determine the pregnancy rate and identify any twin pregnancies. Additionally, at D70, scans were performed to assess pregnancy loss (PG). Data were analysed by orthogonal contrasts [C1 (eCG effect): control x (200 IU + 300 IU) and C2 (eCG dose effect): 200 IU × 300 IU]. On D0, CL presence was similar between the groups [G-0 IU = 65.2% (92/141), G-200 IU = 55.3% (73/132), and G-300 IU = 63.2% (79/125); p = .16]. No interactions between the presence of CL on D0 and eCG treatment were found for any of the variables (p > .05). The diameter of the LF at FTAI (D10) was not influenced by eCG treatment (p = .22) or eCG dose (p = .18). However, treatment with eCG increased the diameter of the CL at D17 (G-0 IU = 15.7 ± 0.3 mmb , G-200 IU = 16.6 ± 0.2 mma , and G-300 IU = 16.6 ± 0.3 mma ; p = .001), regardless of the dose used (p = .94). The ovulation rate was higher in heifers treated with eCG [G-0 IU = 79.4%b (112/141), G-200 IU = 90.2%a (119/132), and G-300 IU = 93.6%a (117/125); p = .002], but there was no effect of eCG dose (p = .36). Pregnancy per AI (P/AI) on D40 [G-0 IU = 32.6%b (46/141), G-200 IU = 42.4%a (56/132), and G-300 IU = 42.4%a (53/125); P = 0.05] and D70 [G-0 IU = 29.1%b (41/141), G-200 IU = 40.9%a (54/132), and G-300 IU = 40.8%a (51/125); p = .02] were higher on heifers that received eCG; however, no dose effect was observed for P/AI on D40 (p = .89) nor D70 (p = .98). Pregnancy loss between D40 and D70 tended to reduce (p = .07) in eCG-treated heifers without dose effect (p = .91). Heifers with CL at D0 presented a greater follicle diameter (LF) on D10 (With CL = 11.2 ± 0.2 mm and Without CL = 10.2 ± 0.2 mm; p = .05), CL diameter on D17 (With CL = 15.8 ± 0.03 mm and Without CL = 11.8 ± 0.6 mm; p = .01), and ovulation rate [With CL = 95.5% (233/244) and Without CL = 74.7% (115/154); p = .01]. However, no difference in pregnancy rate at D40 (p = .52) and D70 (p = .84) was found. In conclusion, eCG treatment increases ovulation and pregnancy rates of heifers submitted to a FTAI protocol. Furthermore, eCG treatment increases the diameter of the CL after FTAI and reduces pregnancy losses. No dose effect was observed, suggesting Nelore (Bos indicus) heifers respond to 200 IU of eCG treatment for FTAI.

Assuntos

Doenças dos Bovinos , Doenças dos Cavalos , Gravidez , Bovinos , Animais , Feminino , Cavalos , Progesterona/farmacologia , Aborto Animal , Ovulação , Estradiol/farmacologia , Cloprostenol/farmacologia , Inseminação Artificial/veterinária , Inseminação Artificial/métodos , Sincronização do Estro/métodos

RESUMO

The objective of this study was to compare the reproductive efficiency of dairy buffaloes undergoing fixed-time artificial insemination (FTAI) protocols based on progesterone/estrogen (P4/E2) and eCG during unfavorable breeding season using cooled (CS) and frozen semen (FS). A total of 446 buffaloes (> 40 days postpartum) were randomly distributed into four blocks (years): B1-2014 (n = 143), B2-2015 (n = 34), B3-2016 (n = 90), and B4-2017 (n = 179). Each block was subdivided into two (AI with CS and FS using the same ejaculate of each bull). Thus, the block subdivision was as follows: B1 (CS = 71 and FS = 72); B2 (CS = 18 and FS = 16); B3 (CS = 47 and FS = 43); and B4 (CS = 90 and FS = 89). The ejaculates of eight Murrah bulls collected using an artificial vagina were divided into two aliquots: one aliquot was diluted in Botu-Bov® commercial extender and cooled (BB-CS), and the other was diluted in the same extender and frozen (BB-FS). BB-CS aliquots were cooled at 5 °C/24 h using a refrigerator. BB-FS group aliquots were also cooled, and after equilibrating at 5 °C for 4 h, were placed in a 21-L Styrofoam box, 5 cm above the surface of liquid nitrogen. In the afternoon (A) on D0 (2:00 p.m.) the animals received EB 2.0 mg IM (Estrogin®) and an ear implant (CRESTAR® 3.0 mg P4). At D9 (A), the implant was removed, and the animals received eCG 400 IU IM (Folligon® 5000) + Cloprostenol PGF2α 0.530 mg IM (Sincrocio®). At D10 (A), the animals received EB 1.0 mg IM (Estrogin®), and at D12 (8:00 a.m.), AI was performed. At D42, pregnancy was diagnosed via ultrasonography. Total CRs were 48.2% CS and 34.6% FS for years 2014 to 2017, with a significant difference of 13.7% (P<0.05). In conclusion, cooled semen resulted in higher CR than frozen semen in dairy buffaloes under the P4/E2 and eCG FTAI during the unfavorable reproductive season.(AU)

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O objetivo deste estudo foi comparar a eficiência reprodutiva de búfalas leiteiras submetidas a protocolos de inseminação artificial em tempo fixo (IATF) à base de progesterona/estrogênio (P4/E2) e eCG, durante a estação reprodutiva desfavorável, usando-se sêmen resfriado (SR) e congelado (SC) Um total de 446 búfalas (> 40 dias após o parto) foi distribuído aleatoriamente em quatro blocos (anos): B1-2014 (n = 143), B2-2015 (n = 34), B3-2016 (n = 90) e B4-2017 (n = 179). Cada bloco foi subdividido em dois (IA com SR e SC utilizando-se a mesma ejaculação de cada touro). Assim, a subdivisão do bloco foi a seguinte: B1 (SR = 71 e SC = 72); B2 (SR = 18 e SC = 16); B3 (SR = 47 e SC = 43); e B4 (SR = 90 e SC = 89). Os ejaculados de oito touros Murrah coletados com vagina artificial foram divididos em duas alíquotas: uma alíquota diluída em diluente comercial Botu-Bov® e resfriada (BB-SR), e a outra diluída no mesmo diluente e congelada (BB-SC). As alíquotas de BB-SR foram resfriados a 5°C/24h usando-se um refrigerador. As alíquotas do grupo BB-SC também foram resfriadas e, após equilíbrio a 5°C por 4h, foram colocadas em uma caixa de isopor de 21L, 5 cm acima da superfície do nitrogênio líquido. À tarde (A), no D0 (14h), os animais receberam BE 2,0 mg IM (Estrogin®) e um implante auricular (Crestar® 3,0 mg P4). No D9 (A), o implante foi retirado e os animais receberam eCG 400 UI IM (Folligon® 5000) + cloprostenol PGF2α 0,530 mg IM (Sincrocio®). No D10 (A), os animais receberam BE 1,0mg IM (Estrogin®), e, no D12 (8h da manhã), foram realizadas as IAs. No D42, a gestação foi diagnosticada por ultrassonografia. As taxas de concepção (TC) totais foram 48,2% SR e 34,6% SC para os anos de 2014 a 2017, com uma diferença significativa de 13,7% (P<0,05). Em conclusão, o sêmen resfriado resultou em maior TC do que o sêmen congelado em bubalinos leiteiros sob P4/E2 e eCG FTAI durante a estação reprodutiva desfavorável.(AU)

Assuntos

Animais , Feminino , Preservação do Sêmen/veterinária , Búfalos/fisiologia , Sincronização do Estro , Progesterona/administração & dosagem , Inseminação Artificial/veterinária , Estrogênios/administração & dosagem

RESUMO

Effects were evaluated in Bos indicus cows of eCG and FSH on follicular growth, estrous expression, and pregnancy per artificial insemination (P/AI) as a result of fixed-time artificial insemination (TAI). In Experiment 1, extent of timing-of-ovulation synchronization among cows was evaluated after imposing an estrogen/progesterone-based treatment regimen. At progesterone device removal (D8), cows were administered: eCG, or FSH or served as untreated Controls. In Experiment 2, percentage of cows P/AI was evaluated when the Experiment 1-treatment regimen was imposed. On D10, all cows were artificially inseminated. In Experiment 3, cows were assigned to two treatment groups (Control and eCG) on D8 to evaluate percentage of cows P/AI and estrous expression. In Experiment 1, follicular dynamics were similar among treatment groups. In Experiment 2, follicular growth was greater (P = 0.0001) with the eCG treatment. There was an interaction of treatment × parity (P = 0.007) on percentage of cows P/AI. There was a greater percentage of primiparous cows P/AI in the eCG-treated than Control and FSH-treated cows. There was a greater percentage of eCG-treated multiparous cows pregnant as a result of TAI than Control cows. There was an interaction of treatment × parity (P = 0.005) on P/AI in Experiment 3, in which the eCG effect was more pronounced in primiparous cows. Treatment with FSH, therefore, was not as effective as eCG in stimulation of follicular growth or enhancing percentage of cows pregnant as a result of TAI. Physiological effects of eCG, however, were also more evident in primiparous cows.

Assuntos

Bovinos , Gonadotropina Coriônica/farmacologia , Estradiol/análogos & derivados , Estro/efeitos dos fármacos , Hormônio Foliculoestimulante/farmacologia , Inseminação Artificial/veterinária , Animais , Gonadotropina Coriônica/administração & dosagem , Esquema de Medicação , Estradiol/administração & dosagem , Estradiol/farmacologia , Feminino , Hormônio Foliculoestimulante/administração & dosagem , Inseminação Artificial/métodos , Paridade , Gravidez , Taxa de Gravidez

RESUMO

This study aimed to minimize the number of times cattle need to be confined during protocols for TAI in beef cows treated for induction of ovulation with EB at the time of P4 device removal (P4r). In Experiment 1, cows were treated with P4 plus EB (Day 0; AM) and were allocated to one of three groups at P4r: EB8.5, EB at P4r on Day 8.5 (PM; three confinements); EB9, EB 24 h after P4r on Day 8 (AM; four confinements) and EC8, EC at P4r on Day 8 (AM; positive control; three confinements). At P4r, cows were treated with PGF2a plus eCG. Ultrasonography was performed from D8 to D12. The interval from P4r to ovulation was less in the EB8.5 compared to EB9 and EC8 group. There was no difference in the ovulation rate between groups. The variability of ovulation was greater in the EB8.5 and EC8 compared to EB9 group. In Experiment 2, cows of EC8 and EB9 groups were submitted to TAI 48 to 52 h (AM) or 54 to 58 h (PM) after P4r (D10). Cows of the EB8.5 group were submitted to TAI 38 to 42 h (AM) or 44 to 48 h (PM) after P4r (D10). There was no interaction between treatments and timing of AI and no treatment effect and timing of AI on P/AI. In conclusion, the delay compared to what typically occurs by 10 h of P4r concomitant with EB administration (Day 8.5) reduced the frequency of animal confinement for the TAI protocol without affecting the reproductive efficiency and the flexibility to perform the TAI in suckled beef cows.

Assuntos

Bovinos , Remoção de Dispositivo , Estradiol/análogos & derivados , Inseminação Artificial , Dispositivos Intrauterinos Medicados , Indução da Ovulação , Animais , Remoção de Dispositivo/veterinária , Estradiol/farmacologia , Sincronização do Estro/métodos , Feminino , Fertilidade/efeitos dos fármacos , Inseminação Artificial/veterinária , Dispositivos Intrauterinos Medicados/veterinária , Folículo Ovariano/efeitos dos fármacos , Ovulação/efeitos dos fármacos , Indução da Ovulação/métodos , Indução da Ovulação/veterinária , Gravidez , Progesterona/administração & dosagem , Fatores de Tempo , Resultado do Tratamento

RESUMO

The objective was to compare the fertility of dairy cows using a presynchronization protocol by induction of a largest follicle using a progesterone intravaginal device prior to an Ovsynch protocol (P4synch) with the Double-Ovsynch in lactating dairy cows. Lactating Bos indicus x Bos taurus crossbred cows (n = 440) were randomly allocated to one of two treatments: (I) Double-Ov (n = 228), GnRH (D-17), PGF2α 7 days later (D-10) and GnRH 3 days later (D-7) followed by an Ovsynch protocol 7 days later (GnRH on D0, PGF on D7, GnRH on D9); (II) P4synch (n = 212), insertion of a sustained release progesterone intravaginal device (D-10), 10 days later (D0) an Ovsynch protocol was initiated (GnRH on D0, PGF on D7, GnRH on D9) with progesterone device withdrawal on Day 7. All cows were artificially inseminated (TAI) 16 h after the second GnRH of the Ovsynch protocol and pregnancy diagnosis was performed by transrectal ultrasonography 30 and 60 days after TAI. A subset of cows (n = 52 for Double-Ov and n = 50 for P4synch) ultrasonography was performed on days 0, 7, 9 and 24 of the experimental period. There were no differences among treatments on presynchronization rate [presence of a follicle>12 mm on D0, Double-Ov 94.2% (49/52) and P4synch 92.0% (46/50); P = 0.66], follicular diameter on the 1st GnRH (Double-Ov 17.2 ±â€¯0.7 mm e P4synch 18.6 ±â€¯0.9 mm; P = 0.28), ovulation rate to the 1st GnRH [Double-Ov 86.3% (44/51) and P4synch 81.2% (39/48); P = 0.50], synchronization rate [presence of a follicle>12 mm on D9; Double-Ov 84.6% (44/52) and P4synch 86.0% (43/50); P = 0.84], follicular diameter on the 2nd GnRH (Double-Ov 17.5 ±â€¯0.6 mm and P4synch 18.0 ±â€¯0.5 mm; P = 0.48), ovulation rate to the 2nd GnRH [Double-Ov 90.9% (40/44) and P4synch 86.0% (37/43); P = 0.48] and CL diameter on D24 (Double-Ov 27.9 ±â€¯0.7 mm and P4synch 29.4 ±â€¯0.9 mm; P = 0.19). Corpus luteum presence on D0 was different (P = 0.03) among treatments [Double-Ov 57.7% (30/52) and P4synch 36.0% (18/50)]. There was no difference (P = 0.85) among the pregnancy per AI on day 30 [Double-Ov 39.0% (89/228) and P4synch 40.1% (85/212)], on day 60 [Double-Ov 34.8% (79/227) and P4synch 38.7% (82/212); P = 0.41] and pregnancy loss [Double-Ov 10.2% (9/88) and P4synch 3.5% (3/85); P = 0.08]. The presynchronization by induction of a largest follicle using a sustained release progesterone device prior to Ovsynch yielded similar results compared with the Double Ovsynch protocol on follicular development patterns and on the fertility of lactating dairy cows.

Assuntos

Bovinos , Hormônio Liberador de Gonadotropina/farmacologia , Folículo Ovariano/efeitos dos fármacos , Progesterona/farmacologia , Animais , Dinoprosta/administração & dosagem , Dinoprosta/farmacologia , Sincronização do Estro , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Ovulação/efeitos dos fármacos , Gravidez , Progesterona/administração & dosagem , Distribuição Aleatória

RESUMO

Two experiments were conducted to assess a hormonal strategy developed to reduce animal handling for timed artificial insemination (TAI) with sex-sorted semen. Four-hundred ninety-one (491) suckled beef cows received a progesterone (P4) intravaginal device and 2 mg intramuscular (im) injection of estradiol benzoate (EB) on a randomly chosen day of the estrus cycle (Day 0) in Experiment 1. Cows were treated with 500 µg of sodic cloprostenol (PGF2α) and with 300 IU of eCG at P4 device removal (Day 8); these cows were also randomly assigned to receive 1 mg of estradiol cypionate (EC) administered at P4 device removal (treatment EC-0h) or 1 mg of EB 24 h after P4 device removal (treatment EB-24h). Both treatments were timed inseminated (TAI) with sex-sorted semen 60 h after P4 device removal. Cows treated with EC-0h presented higher pregnancy rate per AI (P/AI) [45.0% (113/251)] than the ones treated with EB-24h [35.4% (85/240); P = 0.03)]. A subset of cows (n = 26) were subjected to ultrasound examination every 12 h after P4 device removal for 96 h in the row in order to determine the time of ovulation. Similar interval between device removal and ovulation was recorded for EB-24h = 70.0 ±â€¯2.9 h vs. EC-0h = 66.0 ±â€¯2.8 h (P = 0.52). Five-hundred ninety-one (591) cows were subjected to the same synchronization protocols and treatments (EC-0h or EB-24h). In addition, they were randomly assigned to a 2 × 2 factorial arrangement aiming at determining the effects of treatment with estradiol (EC-0h vs. EB-24h) and of semen type (Sex-sorted vs. Non-sex-sorted semen). All animals were timed inseminated 60 h after P4 device removal. There was no interaction (P = 0.07) between the ovulation inducer and semen type. The EC protocol led to greater P/AI than EB (P = 0.03). Greater (P = 0.01) P/AI was achieved through treatments with non-sex-sorted semen rather than with sex-sorted semen [sex-sorted (EB-24h = 49.0%; EC-0h = 51.0%) vs. non-sex-sorted semen (EB-24h = 52.4%; EC-0h = 68.2%)]. Therefore, EC administered at P4 device removal resulted in greater P/AI. Furthermore, the EC-0h protocol allowed reducing suckled beef cow handing for timed artificial insemination with sex-sorted semen.

Assuntos

Criação de Animais Domésticos , Inseminação Artificial/veterinária , Lactação/fisiologia , Pré-Seleção do Sexo , Animais , Bovinos , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Estradiol/farmacologia , Sincronização do Estro/métodos , Feminino , Masculino , Gravidez , Progesterona/administração & dosagem , Progesterona/farmacologia , Sêmen

RESUMO

The aim of this review is to compare the performance of different reproductive programs using natural service, estrus synchronization treatment before natural service (timed natural breeding (TNB)), artificial insemination (AI) following estrus detection and timed artificial insemination (TAI) in beef herds. It is well known that after parturition the beef cow undergoes a period of anestrous, when they do not exhibit estrus, eliminating the opportunity to become pregnant in the early postpartum by natural mating or by AI after detection of estrus. Hormonal stimulation is already a consistent and well-proven strategy used to overcome postpartum anestrus in beef herds. Basically, hormones that normally are produced during the estrous cycle of the cow can be administered in physiological doses to induce cyclicity and to precisely synchronize follicular growth, estrus and ovulation. Furthermore, two options of mating may be used after hormonal stimulation: natural service (i.e. utilization of bull service after synchronization, referred to as TNB) and TAI. These strategies improve the reproductive efficiency of the herds compared with natural service without estrus induction or synchronization. After the first synchronized service, the most common strategy adopted to get non-pregnant cows pregnant soon is the introduction of clean-up bulls until the end of the breeding season. However, methods to resynchronize non-pregnant cows after the first service are already well established and offer a potential tool to reduce the time for subsequent inseminations. Thus, the use of these technologies enable to eliminate the use of bulls by using resynchronization programs (i.e. two, three or four sequential TAI procedures). The dissemination of efficient reproductive procedures, such as TNB, TAI and Resynch programs, either isolated or in combination, enables the production of a greater quantity (obtaining increased pregnancy rates early in the breeding season) and quality (maximization of the use of AI with superior genetic sires) of beef calves. These technologies can contribute to improve the production efficiency, and consequently, improve livestock profitability.

Assuntos

Bovinos , Detecção do Estro , Sincronização do Estro , Inseminação Artificial , Animais , Bovinos/fisiologia , Estro , Feminino , Masculino , Gravidez , Progesterona , Carne Vermelha

RESUMO

The objective of the present study was to evaluate the effect of treatment with prosta-glandin F2α (PGF2α) at the beginning of the protocol for ovulation synchronization on follicular dy-namics in Bos indicus (Gyr; n=11), Bos taurus (Holstein Black and White, HBW; n=10), and crossbred animals (Gyr x HBW; n=12). On a random day of the estrous cycles (day 0, D0), the animals received 2.0 mg estradiol benzoate (EB) intramuscularly plus an intravaginal progesterone (P4) device, which was maintained for 8 days (day 8, D8). Half the heifers of each group received a dose of 25 mg PGF2αintramuscularly at the time of insertion of the intravaginal P4 device. When the intravaginal device was removed (D8), all animals received another dose of 25 mg PGF2α intramuscularly, followed by intramuscular injection of 1.0 mg EB 24 h later (day 9, D9). Ultrasonographic evaluations were per-formed at intervals of 24 hours from D0 to D8 and at intervals of 12 hours from removal of the P4 device to 96 hours thereafter. Samples were collected on days 0, 3, 6, 8, 10 and 22 for the measurement of P4. The mean maximum diameter of the dominant follicle (DF) was smaller (P=0.01) in Gyr heifers (10.0 ± 0.8 mm) than in Gyr x HBW (13.0 ± 0.6 mm) or HBW (12.5 ± 0.8 mm). Furthermore, treatment with PGF2α on D0 increased (P=0.02) the maximum diameter of DF (12.9 ± 0.5 vs. 10.9 ± 0.7 mm)...

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O objetivo do presente estudo foi avaliar o efeito do tratamento com prostaglandina F2α (PGF2α)no início do protocolo de sincronização da ovulação, sobre a dinâmica folicular de novilhas Bos indicus (Gir; n=11), Bos taurus (Holandesa Preto e Branco - HPB; n=10) e cruzadas (Gir x HPB; n=12). Em dia aleatório do ciclo estral (dia 0 - D0), os animais receberam 2,0 mg de benzoato de es-tradiol (BE) via intramuscular, mais um dispositivo intravaginal de progesterona (P4) que foi man-tido por oito dias (dia 8 – D8). Metade das novilhas de cada grupo recebeu uma dose de 25 mg de PGF2α via intramuscular no momento da inserção do dispositivo intravaginal de P4. Na retirada do dispositivo intravaginal (D8), todos os animais receberam outra dose de 25 mg de PGF2α via intra-muscular e 24 h após (dia 9 - D9) receberam 1,0 mg de BE via intramuscular. Foram realizadas ava-liações ultrassonográficas com intervalos de 24 horas do D0 até o D8 e com intervalos de 12 horas da retirada do dispositivo de P4 até 96 horas. Para a dosagem de P4, foram colhidas amostras nos dias 0; 3; 6; 8; 10 e 22. A média do diâmetro máximo do folículo dominante (FD) foi menor (P=0,01) nas novilhas Gir (10,0 ± 0,8 mm) do que nas cruzadas Gir x HPB (13,0 ± 0,6 mm) ou HPB (12,5 ± 0,8 mm). Além disso, o tratamento com PGF2α no D0 aumentou (P=0,02) o diâmetro máximo do FD (12,9 ± 0,5 mm vs. 10,9 ± 0,7 mm) nos três grupamentos genéticos avaliados. A taxa de crescimento do FD foi menor (P=0,008) nas novilhas Gir (0,8 ± 0,1 mm/dia), do que nas novilhas cruzadas (1,3 ± 0,1 mm/dia) ou HPB (1,2 ± 0,1 mm/dia)...

Assuntos

Feminino , Animais , Bovinos , Dinoprosta , Inseminação Artificial/veterinária , Ovulação , Progesterona , Técnicas Reprodutivas/veterinária

RESUMO

The objective of the present study was to evaluate the effect of treatment with prosta-glandin F2α (PGF2α) at the beginning of the protocol for ovulation synchronization on follicular dy-namics in Bos indicus (Gyr; n=11), Bos taurus (Holstein Black and White, HBW; n=10), and crossbred animals (Gyr x HBW; n=12). On a random day of the estrous cycles (day 0, D0), the animals received 2.0 mg estradiol benzoate (EB) intramuscularly plus an intravaginal progesterone (P4) device, which was maintained for 8 days (day 8, D8). Half the heifers of each group received a dose of 25 mg PGF2αintramuscularly at the time of insertion of the intravaginal P4 device. When the intravaginal device was removed (D8), all animals received another dose of 25 mg PGF2α intramuscularly, followed by intramuscular injection of 1.0 mg EB 24 h later (day 9, D9). Ultrasonographic evaluations were per-formed at intervals of 24 hours from D0 to D8 and at intervals of 12 hours from removal of the P4 device to 96 hours thereafter. Samples were collected on days 0, 3, 6, 8, 10 and 22 for the measurement of P4. The mean maximum diameter of the dominant follicle (DF) was smaller (P=0.01) in Gyr heifers (10.0 ± 0.8 mm) than in Gyr x HBW (13.0 ± 0.6 mm) or HBW (12.5 ± 0.8 mm). Furthermore, treatment with PGF2α on D0 increased (P=0.02) the maximum diameter of DF (12.9 ± 0.5 vs. 10.9 ± 0.7 mm)...(AU)

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O objetivo do presente estudo foi avaliar o efeito do tratamento com prostaglandina F2α (PGF2α)no início do protocolo de sincronização da ovulação, sobre a dinâmica folicular de novilhas Bos indicus (Gir; n=11), Bos taurus (Holandesa Preto e Branco - HPB; n=10) e cruzadas (Gir x HPB; n=12). Em dia aleatório do ciclo estral (dia 0 - D0), os animais receberam 2,0 mg de benzoato de es-tradiol (BE) via intramuscular, mais um dispositivo intravaginal de progesterona (P4) que foi man-tido por oito dias (dia 8 D8). Metade das novilhas de cada grupo recebeu uma dose de 25 mg de PGF2α via intramuscular no momento da inserção do dispositivo intravaginal de P4. Na retirada do dispositivo intravaginal (D8), todos os animais receberam outra dose de 25 mg de PGF2α via intra-muscular e 24 h após (dia 9 - D9) receberam 1,0 mg de BE via intramuscular. Foram realizadas ava-liações ultrassonográficas com intervalos de 24 horas do D0 até o D8 e com intervalos de 12 horas da retirada do dispositivo de P4 até 96 horas. Para a dosagem de P4, foram colhidas amostras nos dias 0; 3; 6; 8; 10 e 22. A média do diâmetro máximo do folículo dominante (FD) foi menor (P=0,01) nas novilhas Gir (10,0 ± 0,8 mm) do que nas cruzadas Gir x HPB (13,0 ± 0,6 mm) ou HPB (12,5 ± 0,8 mm). Além disso, o tratamento com PGF2α no D0 aumentou (P=0,02) o diâmetro máximo do FD (12,9 ± 0,5 mm vs. 10,9 ± 0,7 mm) nos três grupamentos genéticos avaliados. A taxa de crescimento do FD foi menor (P=0,008) nas novilhas Gir (0,8 ± 0,1 mm/dia), do que nas novilhas cruzadas (1,3 ± 0,1 mm/dia) ou HPB (1,2 ± 0,1 mm/dia)...(AU)

Assuntos

Animais , Feminino , Bovinos , Dinoprosta , Ovulação , Inseminação Artificial/veterinária , Progesterona , Técnicas Reprodutivas/veterinária