RESUMO
This study was conducted to compare efficacy of treatments with EB or GnRH and different quantities of exogenous progesterone (P4) for synchronization of time of ovulation on follicular growth and pregnancy in lactating dairy cows. In Experiment 1, 40 cows were treated with EB or GnRH and 1.9 or 3.0 g of P4 via progesterone-containing intravaginal devices (IVPD; D0), two doses of PGF2α on D7, GnRH on D9, and TAI on D10. In Experiment 2, 1,440 cows were treated with EB or GnRH and 1 g IVPD on D0, cloprostenol, eCG and EB on D7. Cows in estrus by 48 h were AIDE, and non-estrous cows were administered GnRH and TAI 60 h after IVPD removal. Non-estrous cows were AIDE 72 h after IVPD removal. In Experiment 1, P4 was greater on D7 for cows treated with GnRH than those treated with EB. The dominant follicle was larger for cows treated with GnRH than those treated with EB. In Experiment 2, for estrous cows, pregnancy per AI was greater in cows AI at 48 h compared to 60 h after IVPD removal for cows treated with GnRH, and greater with AI at 60 h after IVPD removal compared to 48 h in EB-treated cows. In non-estrous cows, there was no effect on pregnancy. In conclusion, treatment with GnRH compared with EB resulted in increased P4 regardless of amount of exogenous P4, and there were differential proportions of estrous cows pregnant depending on time of AI after IVPD removal.
Assuntos
Bovinos/fisiologia , Estradiol/farmacologia , Hormônio Liberador de Gonadotropina/farmacologia , Lactação/fisiologia , Folículo Ovariano/efeitos dos fármacos , Progesterona/farmacologia , Administração Intravaginal , Animais , Estradiol/administração & dosagem , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Inseminação Artificial/veterinária , Paridade , Gravidez , Progesterona/administração & dosagemRESUMO
The objective was to compare pregnancy per AI and follicular dynamic in suckled Bos taurus beef cows treated with either a 7-day progesterone + estradiol-based protocol or a 5-day progesterone CoSynch protocol for timed artificial insemination (TAI) during four breeding seasons. We hypothesized that estrous cycle status, days postpartum (DPP), fat depth and plasma progesterone concentration differentially modify the effect of treatments. Every year, 9 days before initiation of each breeding season, cows were randomly assigned to one of two groups. Cows in the 7-d P + E group (n = 428) received a progesterone intravaginal device (DIB) and estradiol benzoate on Day -9. On Day -2 the device was removed, and cows received cloprostenol and estradiol cypionate. Forty-eight hours later (Day 0) cows received TAI. Cows in the 5-d P + CoS group (n = 428) received a DIB, and GnRH on Day -8. On Day -3, the device was removed, and cows received cloprostenol. A second dose of cloprostenol was given on Day -2. Cows received GnRH and TAI 72 h after device removal (Day 0). On Day -9, estrous cycle status was determined. In a subset of cows (n = 79) the size of the dominant follicle was determined between Days -2 and 0. In another subset of cows (n = 340), DPP, fat depth (mm) and plasma progesterone concentration (ng/mL) were evaluated on Day -9. Pregnancy per AI was determined 30 d after TAI. Pregnancy per AI was greater for cows in the 5-d P + CoS group than for cows in the 7-d P + E group (50.9% vs. 41.3%, P = 0.01) and was also greater in cyclic than in anestrus cows (54.3% vs. 33.2%, P < 0.0001). There was also a significant effect of breeding season (P = 0.0002) and sire (P = 0.03), and an interaction between treatment group and breeding season (P = 0.03). The dominant follicle was larger (P < 0.0001) in cows in the 5-d P + CoS group than the 7-d P + E group (10.7 ± 0.29 mm vs. 9.0 ± 0.28 mm). Pregnancy per AI was greater in cows with ≥55 DPP (47.0% vs. 29.6%, P = 0.001), fat depth ≥0.50 mm (44.7% vs. 29.7%), and with plasma progesterone concentration ≥1 ng/mL (47.2% vs. 28.7%, P = 0.01). In cows with plasma progesterone ≥1 ng/mL on Day -9, pregnancy per AI was greater in the 5-d P + CoS group (60.5%) than in the 7-d P + E group (34.9%), but there was no difference between treatment groups in cows with plasma progesterone < 1 ng/mL (P = 0.07). In conclusion, the 5-d P + CoS protocol resulted in greater size of the dominant follicle and pregnancy per AI in suckled Bos taurus beef cows subjected to TAI.
Assuntos
Bovinos , Inseminação Artificial/veterinária , Animais , Estradiol/administração & dosagem , Estradiol/uso terapêutico , Feminino , Inseminação Artificial/métodos , Gravidez , Taxa de Gravidez , Progesterona/administração & dosagem , Progesterona/uso terapêutico , Distribuição Aleatória , Fatores de TempoRESUMO
The objective of this study was to evaluate the effect of an extended progesterone treatment on follicular development and fertility in postpartum, suckled beef cows subjected to timed artificial insemination (TAI). In experiment 1, cows (n = 24) with body condition score (BCS) ≥4.5 received either a 2-g progesterone intravaginal device on Day -23 or a 0.558-g progesterone intravaginal device on Day -9. Then, all cows received 2 mg of estradiol benzoate on Day -9; removal of the device, 1-mg estradiol cypionate, and PGF2α on Day -2; and TAI on Day 0. Metabolic status was assessed between Days -9 and -2. Ovarian structures and plasma progesterone were determined weekly from Day -23 to -9, daily from Day -9 to 0, and weekly until Day 28. In experiment 2, cows (n = 302) with BCS ≥4.5 received identical treatment to cows in experiment 1, but on Day -2, cows received 400 IU of two different commercial preparations of equine chorionic gonadotropin (eCG). Ovarian structures were determined on Days -23 and -9 on a subset of cows (n = 40). Pregnancy was determined 39 days after TAI. In experiment 3, multiparous cows (n = 244) with BCS <5.0 received identical treatment as cows in experiment 1 initiated on Day -18, and on Day -2, cows received 400 IU of eCG or no treatment. Ovarian structures were determined in a subset of cows (n = 31) on Days -3, -2, -1, 0, 1, and on Day 10. Pregnancy was determined 39 days after TAI. The results indicated that in experiment 1, plasma progesterone was higher in treated than nontreated (control cows) during the first 14 days (P = 0.0001). The extended progesterone treatment increased the size of the largest follicle between Days -23 and Day -5 (Group by Day, P = 0.04) and tended to increase the size of the dominant follicle from Day -5 to Day -1 (Group by Day, P = 0.06). There was no effect of metabolic status or interaction between metabolic status and day on follicular growth. In experiment 2, extended progesterone treatment tended to increase the size of the largest follicle between Day -23 and -9 (P = 0.06). There was no effect of Group, eCG, BCS, and parity on pregnancy per AI. In experiment 3, extended progesterone treatment combined with eCG increased the size of the dominant follicle (P = 0.01). Both extended progesterone treatment (P = 0.02) and eCG (P = 0.03) increased pregnancy per AI. In conclusion, an extended progesterone treatment stimulated follicular growth postpartum and improved fertility only in cows with low BCS.
Assuntos
Bovinos/fisiologia , Gonadotropina Coriônica/farmacologia , Inseminação Artificial/veterinária , Progesterona/farmacologia , Animais , Composição Corporal , Peso Corporal , Gonadotropina Coriônica/administração & dosagem , Esquema de Medicação , Feminino , Gravidez , Progesterona/administração & dosagem , Progestinas/administração & dosagem , Progestinas/farmacologia , Substâncias para o Controle da Reprodução/administração & dosagem , Substâncias para o Controle da Reprodução/farmacologiaRESUMO
To describe the epidemiology of cystic ovarian disease (COD), to find possible risk factors associated with the incidence of cysts and to analyse the impact of COD on the reproductive performance of dairy cows, databases from 22 dairy herds from the main dairy region in Argentina were retrospectively evaluated throughout a 3-year period (2009-2011). A total of 248 COD cases over 9156 parturitions were recorded, resulting in a cumulative incidence rate of 2.7%. Cystic ovarian disease incidence density was lower during the first 100 days post-partum (DPP) than during later stages of lactation. Seasonality had a significant influence on the disease presentation with higher incidence rates during winter and spring. Cows with a previous diagnosis of clinical mastitis showed 2.72 times more chances of developing ovarian cysts. Cystic cows had longer calving to first service and calving to conception intervals and lower conception rate than controls.
Assuntos
Argentina/epidemiologia , Doenças dos Bovinos/epidemiologia , Cistos Ovarianos/veterinária , Animais , Estudos de Casos e Controles , Bovinos , Feminino , Incidência , Lactação , Razão de Chances , Fatores de RiscoRESUMO
The objective was to evaluate the effect of equine chorionic gonadotropin (eCG) and hCG post artificial insemination (AI) on fertility of lactating dairy cows. In Experiment 1, cows were either treated with eCG on Day 22 post AI (400 IU; n = 80) or left untreated (n = 84). On Day 29, pregnant cows were either treated with hCG (2500 IU; n = 32) or left untreated (n = 36). Pregnancy and progesterone were evaluated on Days 29 and 45. In Experiment 2, cows (n = 28) were either treated with eCG on Day 22 (n = 13) or left untreated (n = 15) and either treated with hCG on Day 29 (n = 14) or left untreated (n = 14). Blood sampling and ultrasonography were conducted between Days 22 and 45. In Experiment 3, cows were either treated with eCG on Day 22 post AI (n = 229) or left untreated (n = 241). Pregnancy was evaluated on Days 36 and 85. In Experiment 1, eCG on Day 22 increased (P < 0.02) the number of pregnant cows on Day 29 (50.0 vs. 33.3%) and on Day 45, the increase was higher (P < 0.01) in cows with timed AI (41.2 vs. 6.5%) than in cows AI at detected estrus (50.0 vs. 37.8%). Pregnancy losses were reduced by eCG and hCG, but increased in cows that did not receive eCG but were given hCG (P < 0.01). Treatment with hCG tended (P < 0.06) to increase progesterone in control cows, but not in cows treated with eCG. In Experiment 2, hCG increased (P < 0.01) the number of accessory CLs on Day 35 (28.5 vs. 0.0%) and tended (P < 0.07) to increase progesterone. In Experiment 3, eCG increased the number of pregnant cows (P < 0.05) on Days 36 and 85, but only in cows with low body condition (eCG = 45.6 and 43.5%; Control = 22.9 and 22.9%). In conclusion, eCG at 22 days post insemination increased fertility, primarily in cows with low body condition and reduced pregnancy losses when given 7 days before hCG; hCG induced accessory CLs and slightly increased progesterone, but hCG given in the absence of a prior eCG treatment reduced fertility.
Assuntos
Bovinos/fisiologia , Gonadotropina Coriônica/farmacologia , Fármacos para a Fertilidade Feminina/farmacologia , Inseminação Artificial/veterinária , Lactação , Animais , Gonadotropina Coriônica/administração & dosagem , Feminino , Fármacos para a Fertilidade Feminina/administração & dosagem , Cavalos , Humanos , GravidezRESUMO
Pregnancy per artificial insemination (AI) was evaluated in dairy cows (Bos taurus) subjected to synchronization and resynchronization for timed AI (TAI). Cows (n=718) received prostaglandin F(2alpha) (PGF) on Days -38 and -24 (Days 39 and 53 postpartum), gonadotropin-releasing hormone (GnRH) on Day -10, PGF on Day -3, and GnRH and TAI on Day 0. Between Days -10 and -3, cows received a progesterone intravaginal insert (CIDR group) or no CIDR (Control group). Between Days 14 and 23, cows received a CIDR (Resynch CIDR group) or no CIDR (Resynch control group), GnRH on Day 23, with pregnancy diagnosis on Day 30. Cows in estrus (between Days 0 and 30) were re-inseminated at detected estrus (RIDE). Nonpregnant cows received PGF on Day 30 and GnRH and TAI on Day 33. Plasma progesterone was determined to be low or high on Days -24 and -10. Pregnancy rates were evaluated 30 and 55 d after AI. The CIDR insert included in the Presynch-Ovsynch protocol did not increase overall pregnancy per AI for first service (36.1% and 33.6% for CIDR; 34.1% and 28.8% for Control) but did decrease pregnancy loss (7.0% for CIDR and 15.6% for Control). The CIDR insert increased pregnancy per AI in cows with high progesterone at the time the CIDR insert was applied. Administration of a CIDR insert between Days 14 and 23 of the estrous cycle after first service did not increase overall pregnancy per AI to second service (24.7% and 22.7% for Resynch CIDR; 28.6% and 25.3% for Resynch control). For second service, RIDE cows had lower pregnancy rates in the Resynch CIDR group than in the Resynch control group. Cows with a CL (corpus luteum) at Day 30 had higher pregnancy rates in the Resynch CIDR group than those in the Resynch control group.