RESUMO
This experiment aimed to compare circulating progesterone (P4), follicular dynamics, and fertility during reuse of intravaginal P4 implants that were sanitized by autoclave or chemical disinfection in lactating Holstein cows submitted to fixed-time artificial insemination (FTAI). For this, 123 primiparous and 226 multiparous cows from 2 farms, averaging (mean ± standard deviation) 163.9 ± 141.9 d in milk, 35.7 ± 11.3 kg of milk/d, and a body condition score of 2.9 ± 0.5, were enrolled in the study. Cows were randomly assigned to 1 of 2 treatments using a completely randomized design and each cow received a reused implant (1.9 g of P4; previously used for 8 d) that was either autoclaved (AUT; n = 177) or chemically disinfected (CHEM; n = 172) on d -10. Also on d -10, cows received 2 mg of estradiol benzoate and 100 µg of GnRH. On d -3, cows received 25 mg of dinoprost (PGF2α). A second PGF2α was given on d -2, along with 1 mg of estradiol cypionate and P4 implant removal. Cows received FTAI on d 0. A subset of cows (n = 143) was evaluated by ultrasound on d -10, -8, -6, -3, -2, 0, and 5 to identify ovarian structures, and blood was sampled on d -10, -3, and -2 for P4 concentrations by RIA. Pregnancy diagnoses were performed at d 32 and 60. Statistical analyses was performed using PROC-MIXED for continuous variables and PROC-GLIMMIX of SAS 9.4 (SAS Institute Inc., Cary, NC) for binomial variables. The treatments did not differ in circulating P4 on d -10 or -3, but P4 was greater on d -2 in CHEM cows. Ovulation to the treatments on d -10 was associated with lower circulating P4 on d -10 (2.0 vs. 3.1 ng/mL) and resulted in greater P4 on d -3 (4.0 vs. 2.4 ng/mL) and more cows with a corpus luteum on d -3 (100 vs. 40%) than nonovulating cows. Cows that ovulated to d -10 treatments were more likely to have a synchronized new follicular wave (97.9 vs. 63.2%) and had an earlier wave emergence (1.9 vs. 2.6 d), resulting in less cows ovulating a persistent follicle (0.0 vs. 35.7%). Type of P4 implant, corpus luteum presence on d -10, and ovulation to d -10 treatments did not affect fertility (pregnancy per AI; P/AI). However, P/AI on farm A was greater than on farm B at 32 (40.8 vs. 27.8%) and 60 d (35.8 vs. 24.3%), independent of treatment. In conclusion, P4 implants with different P4 release patterns did not produce detectable differences in follicular dynamics, synchronization rate, or P/AI. Nevertheless, presence of corpus luteum or ovulation at the beginning of the FTAI protocol affected reproductive variables, such as timing and synchronization of follicular wave emergence, and size of the ovulatory follicle. Beyond that, more overall synchronized cows became pregnant to the FTAI protocol.
Assuntos
Bovinos , Desinfecção/métodos , Implantes de Medicamento , Reutilização de Equipamento/veterinária , Sincronização do Estro , Fertilidade , Progesterona/administração & dosagem , Administração Intravaginal , Animais , Bovinos/sangue , Dinoprosta/administração & dosagem , Estradiol/administração & dosagem , Estradiol/análogos & derivados , Sincronização do Estro/métodos , Feminino , Hormônio Liberador de Gonadotropina/administração & dosagem , Lactação , Leite , Folículo Ovariano/metabolismo , Ovulação , Gravidez , Progesterona/sangueRESUMO
The objective of this study was to test the hypothesis that high-producing dairy cows become increasingly resistant to insulin throughout lactation and that, consequently, oocyte quality is compromised. We used Holstein cows at 50 (51.5±3.7; n=30), 100 (102.3±9.4; n=30), and 150 (154.5±18.9; n=30) days in milk (DIM). We measured circulating insulin and glucose and performed a glucose tolerance test (GTT) after 5h of fasting. To evaluate oocyte quality, we performed ovum pickup on the day before the GTT (581 oocytes). We performed statistical analyses using the MIXED procedure of SAS. The model included the fixed effects of DIM, period, time, parity, and an interaction between DIM and time. We observed no difference in the GTT between groups for any variable related to circulating glucose (for example, glucose peak=203.3±7.2, 208.8±6.3, and 194.3±5.9mg/dL). However, various measures of circulating insulin were different in cows at 150 DIM compared with 50 or 100 DIM: higher basal insulin (8.8±0.9, 8.8±0.8, and 11.9±0.8 µIU/mL), peak insulin (61.9±6.2, 69.1±5.7, and 89.0±6.1 µIU/mL), delta maximum insulin (51.1±5.5, 59.4±5.0, and 73.5±5.4 µIU/mL), and area under the curve 5-60 (1,874.8±171.0, 2,189.5±157.8, and 2,610.5±174.0 µIU/mL × min). Nevertheless, we observed no difference among groups in the number of viable oocytes (3.2±0.7, 3.9±0.7, and 3.6±0.7 per cow per ovum pickup) or percentage of viable oocytes (49.3, 52.2, and 51.8%). Increased circulating insulin before and throughout the GTT in cows at 150 DIM indicates that cows develop increasing insulin resistance with increasing DIM; however, increased insulin resistance was not associated with a detectable alteration in the quality of oocytes aspirated from small and medium-sized follicles.
Assuntos
Dieta/veterinária , Resistência à Insulina , Animais , Bovinos , Feminino , Insulina , Lactação , Leite , OócitosRESUMO
Diets can alter the concentrations of circulating hormones such as insulin and IGF_I. Such responsive hormones are related directly to nutritional status and moreover, directly or indirectly associated with reproductive function and fertility. Metabolic hormones are involved in follicular development, number and size of ovarian structure, circulating concetrations of steroid hormones duration of estrus, steroidogenesis, ovulation and embryonic development. Howeverm circulating metabolic hormones in excess, resulting from high dry matter/energy intake can also contribute to the reduction of oocytes and embryo quality. Although changes in dietary intake affect ovarian funciton in Bos taurus and Bos indicus cattle, it seems that overfeeding influences more profoundly oocytes/embryos from heifers and cows of Bos taurus than of Bos indicus breeds. There is also a distinct effect of nutrition on in vitro vs. in vivo embryo production, in which metabolic hormones seem to affect more the la ter stages of follicle development. Thus, this paper presents and discusses the results of some relevant studies on the role of feed intake and its association with metabolic hormones in mbovinemreproduction.(AU)
Assuntos
Animais , Insulina/química , Hormônios/biossíntese , Fertilidade/fisiologia , Esteroides , Bovinos/fisiologia , Embrião de Mamíferos/embriologiaRESUMO
Diets can alter the concentrations of circulating hormones such as insulin and IGF_I. Such responsive hormones are related directly to nutritional status and moreover, directly or indirectly associated with reproductive function and fertility. Metabolic hormones are involved in follicular development, number and size of ovarian structure, circulating concetrations of steroid hormones duration of estrus, steroidogenesis, ovulation and embryonic development. Howeverm circulating metabolic hormones in excess, resulting from high dry matter/energy intake can also contribute to the reduction of oocytes and embryo quality. Although changes in dietary intake affect ovarian funciton in Bos taurus and Bos indicus cattle, it seems that overfeeding influences more profoundly oocytes/embryos from heifers and cows of Bos taurus than of Bos indicus breeds. There is also a distinct effect of nutrition on in vitro vs. in vivo embryo production, in which metabolic hormones seem to affect more the la ter stages of follicle development. Thus, this paper presents and discusses the results of some relevant studies on the role of feed intake and its association with metabolic hormones in mbovinemreproduction.
Assuntos
Animais , Esteroides , Fertilidade/fisiologia , Hormônios/biossíntese , Insulina/química , Bovinos/fisiologia , Embrião de Mamíferos/embriologiaRESUMO
Circulating concentration of progesterone (P4) is determined by a balance between P4 production, primarily by corpus luteum (CL), and P4 metabolism, primarily by liver. The volume of large luteal cells in the CL is a primary factor regulating P4 production. Rate of P4 metabolism is generally determined by liver blood flow and can be of critical importance in determining circulating P4 concentrations, particularly in dairy cattle. During timed AI protocols, elevations in P4 are achieved by increasing number of CL by ovulation of accessory CL or by supplementation with exogenous P4. Dietary manipulations, such as fat supplementation, can also be used to alter circulating P4. Elevating P4 prior to the timed AI generally decreases double ovulation an d can increase fertility to the timed AI. This appears to be an effect of P4 during the follicular wave that produces the future ovulatory follicle, possibly by altering the oocyte and subsequent embryo. Near the time of AI, slight elevations in circulating P4 can dramatically reduce fertility. The etiology of slight elevations in P4 near AI is inadequate luteolysis to the prostaglandin F2 α (PGF) treatment prior to timed AI. After AI, circulating P4 is critical for embryo growth and establishment and maintenance of pregnancy. Many studies have attempted to improve fertility by elevating P4 after timed AI. Combining results of these studies indicated only marginal fertility benefits of <5%. In conclusion, previous research has provided substantial insight into the effects of supplemental P4 on fertility and there is increasing insight into the mechanisms regulating circulating P4 concentrations and actions. Understanding this prior research can focus future re search on P4 manipulation to improve timed AI protocols.(AU)
Assuntos
Animais , Prenhez/fisiologia , Corpo Lúteo/anatomia & histologia , Folículo Ovariano/anatomia & histologia , Ruminantes/classificação , Primatas/classificaçãoRESUMO
Circulating concentration of progesterone (P4) is determined by a balance between P4 production, primarily by corpus luteum (CL), and P4 metabolism, primarily by liver. The volume of large luteal cells in the CL is a primary factor regulating P4 production. Rate of P4 metabolism is generally determined by liver blood flow and can be of critical importance in determining circulating P4 concentrations, particularly in dairy cattle. During timed AI protocols, elevations in P4 are achieved by increasing number of CL by ovulation of accessory CL or by supplementation with exogenous P4. Dietary manipulations, such as fat supplementation, can also be used to alter circulating P4. Elevating P4 prior to the timed AI generally decreases double ovulation an d can increase fertility to the timed AI. This appears to be an effect of P4 during the follicular wave that produces the future ovulatory follicle, possibly by altering the oocyte and subsequent embryo. Near the time of AI, slight elevations in circulating P4 can dramatically reduce fertility. The etiology of slight elevations in P4 near AI is inadequate luteolysis to the prostaglandin F2 α (PGF) treatment prior to timed AI. After AI, circulating P4 is critical for embryo growth and establishment and maintenance of pregnancy. Many studies have attempted to improve fertility by elevating P4 after timed AI. Combining results of these studies indicated only marginal fertility benefits of <5%. In conclusion, previous research has provided substantial insight into the effects of supplemental P4 on fertility and there is increasing insight into the mechanisms regulating circulating P4 concentrations and actions. Understanding this prior research can focus future re search on P4 manipulation to improve timed AI protocols.
Assuntos
Animais , Corpo Lúteo/anatomia & histologia , Folículo Ovariano/anatomia & histologia , Prenhez/fisiologia , Primatas/classificação , Ruminantes/classificaçãoRESUMO
This study investigated the effect of porcine follicular fluid (PFF) and dibutyryl cyclic adenosine monophosphate (dbcAMP) during in vitro maturation (IVM) of porcine oocytes on meiotic maturation, fertilization and embryo development, and compared the effect of supplementing the embryo culture media with PFF or foetal bovine serum (FBS) on embryo development. Oocytes from pre-pubertal gilts were IVM for 44 h, and parthenogenetically activated or in vitro-fertilized. Embryos were cultured in porcine zygote medium (PZM3) for 7 days. Cleavage and blastocyst rates were evaluated at 48 h and 7 days of culture. The supplementation of the IVM medium with 25% PFF and 1 mm dbcAMP for the first 22 h resulted in more (p < 0.05) embryos developing to the blastocyst stage as compared with the inclusion of dbcAMP alone. The dbcAMP + PFF combination increased (p < 0.05) the average number of nuclei per blastocyst as compared with either of these components alone or in its absence. A synergistic effect of dbcAMP + PFF during IVM was also reflected in the capacity of oocytes to regulate sperm penetration and prevent polyspermy, as twice as many oocytes from the control group were penetrated by more than one sperm as compared with those matured in the presence of both dbcAMP and PFF. The supplementation of PZM3 with 10% FBS from days 5 to 7 of culture significantly improved the total cell quantity in embryos derived either from control or dbcAMP + PFF matured oocytes. There was no effect on the total cell quantity when FBS was replaced by the same concentration of PFF. These studies showed that dbcAMP, PFF and FBS can improve both the quantity (57.3% vs 41.5%) and quality (74.8 vs 33.3 nuclei) of porcine blastocysts derived from oocytes recovered of pre-pubertal gilts.
Assuntos
Bucladesina/farmacologia , Líquido Folicular/metabolismo , Oócitos/efeitos dos fármacos , Oócitos/fisiologia , Partenogênese/efeitos dos fármacos , Suínos/fisiologia , Animais , Técnicas de Cultura de Células/veterinária , Desenvolvimento Embrionário , FemininoRESUMO
The learned helplessness (LH) paradigm is characterized by learning deficits resulting from inescapable events. The aims of the present study were to determine if protein-calorie malnutrition (PCM) alters learning deficits induced by LH and if the neurochemical changes induced by malnutrition alter the reactivity to treatment with GABA-ergic and serotonergic drugs during LH. Well-nourished (W) and PCM Wistar rats (61 days old) were exposed or not to inescapable shocks (IS) and treated with gepirone (GEP, 0.0-7.5 mg/kg, intraperitoneally, N = 128) or chlordiazepoxide (0.0-7.5 mg/kg, intraperitoneally, N = 128) 72 h later, 30 min before the test session (30 trials of escape learning). The results showed that rats exposed to IS had higher escape latency than non-exposed rats (12.6 ± 2.2 vs 4.4 ± 0.8 s) and that malnutrition increased learning impairment produced by LH. GEP increased the escape latency of W animals exposed or non-exposed to IS, but did not affect the response of PCM animals, while chlordiazepoxide reduced the escape deficit of both W and PCM rats. The data suggest that PCM animals were more sensitive to the impairment produced by LH and that PCM led to neurochemical changes in the serotonergic system, resulting in hyporeactivity to the anxiogenic effects of GEP in the LH paradigm.
Assuntos
Animais , Masculino , Ratos , Aprendizagem da Esquiva/efeitos dos fármacos , Moduladores GABAérgicos/farmacologia , Desamparo Aprendido , Desnutrição Proteico-Calórica/tratamento farmacológico , Pirimidinas/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Análise de Variância , Peso Corporal , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Clordiazepóxido/farmacologia , Clordiazepóxido/uso terapêutico , Modelos Animais de Doenças , Reação de Fuga/efeitos dos fármacos , Reação de Fuga/fisiologia , Moduladores GABAérgicos/uso terapêutico , Deficiências da Aprendizagem/etiologia , Desnutrição Proteico-Calórica/fisiopatologia , Desnutrição Proteico-Calórica/psicologia , Pirimidinas/uso terapêutico , Ratos Wistar , Agonistas do Receptor de Serotonina/uso terapêuticoRESUMO
The learned helplessness (LH) paradigm is characterized by learning deficits resulting from inescapable events. The aims of the present study were to determine if protein-calorie malnutrition (PCM) alters learning deficits induced by LH and if the neurochemical changes induced by malnutrition alter the reactivity to treatment with GABA-ergic and serotonergic drugs during LH. Well-nourished (W) and PCM Wistar rats (61 days old) were exposed or not to inescapable shocks (IS) and treated with gepirone (GEP, 0.0-7.5 mg/kg, intraperitoneally, N = 128) or chlordiazepoxide (0.0-7.5 mg/kg, intraperitoneally, N = 128) 72 h later, 30 min before the test session (30 trials of escape learning). The results showed that rats exposed to IS had higher escape latency than non-exposed rats (12.6 +/- 2.2 vs 4.4 +/- 0.8 s) and that malnutrition increased learning impairment produced by LH. GEP increased the escape latency of W animals exposed or non-exposed to IS, but did not affect the response of PCM animals, while chlordiazepoxide reduced the escape deficit of both W and PCM rats. The data suggest that PCM animals were more sensitive to the impairment produced by LH and that PCM led to neurochemical changes in the serotonergic system, resulting in hyporeactivity to the anxiogenic effects of GEP in the LH paradigm.
Assuntos
Aprendizagem da Esquiva/efeitos dos fármacos , Moduladores GABAérgicos/farmacologia , Desamparo Aprendido , Desnutrição Proteico-Calórica/tratamento farmacológico , Pirimidinas/farmacologia , Agonistas do Receptor de Serotonina/farmacologia , Análise de Variância , Animais , Comportamento Animal/efeitos dos fármacos , Comportamento Animal/fisiologia , Peso Corporal , Clordiazepóxido/farmacologia , Clordiazepóxido/uso terapêutico , Modelos Animais de Doenças , Reação de Fuga/efeitos dos fármacos , Reação de Fuga/fisiologia , Moduladores GABAérgicos/uso terapêutico , Deficiências da Aprendizagem/etiologia , Masculino , Desnutrição Proteico-Calórica/fisiopatologia , Desnutrição Proteico-Calórica/psicologia , Pirimidinas/uso terapêutico , Ratos , Ratos Wistar , Agonistas do Receptor de Serotonina/uso terapêuticoRESUMO
Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnologies. Subjective evaluation to determine embryo viability is often used. The determination of the best cryopreservation protocol depends on morphological and molecular analysis of cellular injuries. The main objective of this study was to compare two methods of cryopreservation by assessing morphological alterations of frozen embryos using light, fluorescence, and transmission electron microscope. Fresh (control), slow frozen, and vitrified mouse embryos were composed. To evaluate the viability of the embryos, the cell membrane integrity was assessed using Hoechst33342 and propidium iodide (H/PI) staining. Morphological analyses using hematoxylin and eosin (HE) staining were performed to test different techniques (in situ, paraffin, and historesin) by both light and fluorescence microscopy. Transmission electron microscope was used to detect ultrastructural alterations in Spurr- and Araldite-embedded samples. H/PI staining detected more membrane permeability in the vitrification (69.8%) than in the slow freezing (48.4%) or control (13.8%) groups (P < 0.001). Historesin-embedded samples showed to be more suitable for morphological analyses because cellular structures were better identified. Nuclear evaluation in historesin sections showed the induction of pycnosis in slow freezing and vitrification groups. Cytoplasm evaluation revealed a condensation and an increase in eosinophilic intensity (indicating apoptosis) in the slow freezing group, and weakly eosinophilic structures and degenerated cells (indicating oncosis) in the vitrification group (P < 0.05). Ultrastructural analyses confirmed HE morphological findings. It was concluded that both cryopreservation techniques resulted in oncosis and apoptosis injuries. However, vitrification caused more severe cellular alterations and reduced embryonic viability compared to slow freezing.