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The study tested the hypothesis that a single administration of hCG supports the LH-dependent phase of terminal follicular development in synchronized sheep during anestrus, using eCG as a functional reference. Using a clinical approach, four experiments were designed to achieve the following: (1) Identify the inhibitory influence of anestrus on reproduction efficiency; (2) Assess the potential of hCG to keep functional blood concentrations after a single dose; (3) Characterize the effect of different doses of hCG on reproductive functional markers; (4) To compare the ability of hCG to that of eCG to support follicular development and fertility based on the same markers. The results showed that anestrus seems to affect follicular and luteal function under LH dependency as FSH-dependent markers are not compromised; hCG maintains higher blood concentrations than controls for at least 48 h; hCG improves follicular development and ovulatory rates compared to controls and at standards comparable to a breeding season; and ewes treated with hCG exhibit similar performance to those treated with eCG. Our results conclude that hCG can be used to support follicular function during anestrus in sheep, aiming to perfect its regulation in assisted reproduction.

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Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.

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Hormonal methodologies to control small ruminants' estrous cycle are worldwide used and evolved, adjusting the application to the precise female physiological moments to enhance reproductive performance. The estrous cycle can be induced and/or synchronized, aiming for fixed-time artificial insemination, or based on estrus behavior signs for insemination, natural or guided mating. Successive protocols can be performed to resynchronize ovulation and increase reproductive outcomes in females that failed to conceive. These recently developed treatments aim to resynchronize the ovulation as earlier as non-pregnancy is detected. The present review aimed to summarize the recent advances and main findings regarding resynchronization protocols used in small ruminants. Lastly, we present future perspectives and new paths to be studied in the subject. The resynchronization treatment is still a growing field in small ruminant reproduction, nevertheless, some enhancements are found in the reproductive outcome, showing that such protocols can be successfully used in sheep and goat production.(AU)

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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.

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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.

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Abstract Background: Proper timing for embryo collection and transfer in horses -which is critical for the success of this biotechnology- is still debated. Additionally, there is little information on this technology under tropical conditions. Objective: To determine the best day for collection and transfer of embryos in Mangalarga Marchador mares under Brazilian northeast's conditions. Methods: Donors (n= 30) and recipients (n= 76) in diestrus phase were selected based on both clinical and gynecology examinations. Estrus was induced on both donor and recipient mares by intramuscular injection of 5 mg Dinoprost, aiming to obtain an ovulation interval of -1 to +3 between recipient and donor. Ovulation was induced with buserelin acetate when the largest follicle reached at least 35 mm in diameter. At this time, mares were subjected to artificial insemination at 48-hour intervals until ovulation. The embryos were collected on days 7, 8, and 9 after ovulation. Results: The embryo collection on day 8 was more efficient (p<0.05) than on day 7, but it was not more effective (p>0.05) than day 9, which presented the same efficiency (p>0.05) as day 7. From a total of 76 embryos transferred to the recipients, that were between days 4 and 9 after ovulation, there was no influence (p>0.05) of the day of transfer on pregnancy rate. Conclusions: The embryo collection must be performed on day 8 after ovulation, and transfer can be performed on any day of that interval (4-9) without affecting the pregnancy rate.

Resumen Antecedentes: El momento mas apropiado para la recolección y transferencia de embriones en equinos -que es fundamental para el éxito de esta biotecnología- continua siendo sujeto de estudio. Además, es escasa la información sobre esta tecnología en condiciones tropicales. Objetivo: Determinar el momento mas adecuado para la recolecta y transferencia de embriones en yeguas Mangalarga Marchador, en las condiciones del nordeste Brasileño. Métodos: Donadoras (n= 30) y receptoras (n= 76) en la fase de diestro se seleccionaron con base en los exámenes clínicos y ginecológicos. El estro de las yeguas donadoras y receptoras fue inducido con 5 mg de Dinoprost, vía intramuscular, intentando obtener un intervalo de ovulación de -1 a +3 entre la receptora y la donadora. La ovulación fue inducida con acetato de buserelina cuando el folículo mayor alcanzó 35 mm de diámetro. En ese momento, las yeguas fueron sometidas a inseminación artificial en intervalos de 48 horas hasta la ovulación. Los embriones fueron recolectados en los días 7, 8 y 9 después de la ovulación. Resultados: La recolecta de embriones en el día 8 fue más eficiente (p<0,05) que en el día 7, pero no fue más efectivo (p>0,05) que en el día 9, el cuál presentó la misma eficiencia (p>0,05) que en el día 7. De un total de 76 embriones transferidos a las receptoras, que se encontraban entre el día 4 y 9 después de la ovulación, no se registró influencia (p>0,05) del día de la transferencia en la tasa de preñez. Conclusiones: La recolecta embrionaria debe ser realizada el día 8 después de la ovulación, y la transferencia puede ser realizada en cualquier día de este intervalo (4 a 9) sin que se afecte la tasa de preñez.

Resumo Antecedentes: A importância do momentoda colheita e da transferência do embrião equino para o sucesso dessa biotécnica em equino continua sem ser completamente entendida. Adicionalmente, existe pouca informação sobre essa tecnologia em condições tropicais. Objetivo: Determinar o melhor dia para colheita e para transferência de embriões em eguas manga larga marchador nas condições do nordeste brasileiro. Métodos: Doadoras (n = 30) e receptoras (n = 76) na fase de diestro foram selecionadas com base nos exames clínico e ginecológicos. O estro das éguas doadoras e receptoras foi induzido com 5 mg de Dinoprost administrado por via intramuscular, buscando obter um intervalo de ovulação de -1 a +3 entre a receptora e a doadora. A ovulação foi induzida com acetato de buserelina quando o foliculo maior alcançou o tamanho de 35 mm de diâmetro. Nesse momento, as éguas foram submetidas a inseminação artificial em intervalos de 48 horas até a ovulação. Os embriões foram colhidos nos dias 7, 8 e 9 depois da ovulação. Resultados: A colheita de embriões no dia 8 foi mais eficiente (p<0,05) do que no dia 7, porem não foi mais efetivo (p>0,05) do que o dia 9, o qual apresentou a mesma eficiência (p>0,05) que o dia 7. De um total de 76 embriões transferidos para as receptoras que se encontravam entre os dias 4 e 9 depois da ovulação, não se registrou influência (p>0,05) do dia da transferência sobre a taxa de prenhez. Conclusões: A colheita embrionária deve ser realizada no dia 8 depois da ovulação, e a transferência pode ser realizada em qualquer dia desse intervalo (4-9) sem que a taxa de prenhez seja afetada.

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2-alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2-alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2-alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2-alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2 -alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat content was found in the PRID group as 2.47 ± 0.354%, and the highest value was in the PGF2 -alpha group as 3.58 ± 0.207%. The difference in milk fat ratio between the groups was found to be significant (P < .05). However, the differences between the groups for other parameters were not significant (P > .05).[...](AU)

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2 -alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat content was found in the PRID group as 2.47 ± 0.354%, and the highest value was in the PGF2 -alpha group as 3.58 ± 0.207%. The difference in milk fat ratio between the groups was found to be significant (P .05).[...]

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Background: Estrous synchronization is one of the primary applications performed to improve the fertility and to consolidate the parturition times in dairy cattle farms. Since the primary objective is to increase fertility regardless of the method of synchronization used, the effect of this process on the udder health and the quality of milk is generally ignored. Therefore, in the present study, the aim was to investigate the effect of different estrous synchronization methods t on the milk quality in a dairy cattle farm.Materials, Methods & Results: In this study, a total of 100 Simmental cows the same farm under good management practices were used. The animals were randomly divided into 4 groups of 25 cows each. The animals in the 1st group were used as a control group without any treatment. Progesterone-releasing intravaginal device (PRID) was inserted to the animals in the 2nd group, double dose of prostaglandin F2 alpha (PGF2-alpha) with 11 days apart was applied to the animals in the 3rd group, and the Ovsynch protocol was applied to the animals in the 4th group. Starting from the first day of the applications, milk samples from each milk tank belonging to the groups were taken, kept frozen for 3 months and analyzed for the levels of fat, nonfat solids, density, protein, lactose and minerals over the course of one month. According to the results, the minimum milk fat

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The use of intravaginal sponges (IS) to synchronize estrous onset in ewes provokes vaginitis, an increase in the vaginal bacterial load, and growth of bacterial species that are not present during spontaneous estrous behavior. The objective of the study was to compare the functional sperm parameters after incubating it with mucus collected from the vagina of ewes during spontaneous estrus or estrous synchronized with IS. Pooled spermatozoa were co-incubated with: (1) vaginal mucus collected from ewes in spontaneous estrus; (2) vaginal mucus collected from ewes in estrus pretreated with progestogen-impregnated IS; (3) synthetic mucus; and (4) medium without mucus as a control group. Sperm samples were evaluated after incubating it for 30 and 90 minutes. The number of colony-forming units (CFUs/mL), pH, and osmolality were greater in the mucus collected from ewes treated with IS than from those untreated (P = 0.046; P < 0.0001, and P < 0.0001, respectively). The percentage of sperm with progressive motility was lower after incubation with vaginal mucus collected from estrous ewes treated with IS than in the other three treatments both, 30 and 90 minutes after incubation (P = 0.0009 and P < 0.0001, respectively). The sample incubated for 30 minutes with mucus from ewes treated with IS had a lower percentage of sperm with intact plasma membrane than all the other treatments (P < 0.0001). The percentage of sperm with functional membrane was significantly lower in the sample incubated for 30 minutes with vaginal mucus from ewes treated with IS than in the other three treatments (P < 0.0001). After 90 minutes, the percentage was still lower than that in the sample collected from ewes during their spontaneous estrus (P = 0.0005). The lowest percentages of sperm with acrosome damage were observed in sperm incubated with mucus collected from sheep in spontaneous estrus for 30 and 90 minutes (P < 0.0001 and P = 0.008, respectively). The percentage of apoptotic spermatozoa was greater in samples incubated during 30 minutes with vaginal mucus collected from ewes treated with IS than in the other three groups (P = 0.0005). The functionality and the viability of ram sperm is negatively affected by the cervical mucus of ewes pretreated with progestagen-impregnated IS used in estrous synchronization treatments. This may partially explain the decrease in conception rate obtained with treatments with IS.

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This study was done to evaluate the efficiency of GnRH along with long-term and short-term synchronization protocols on ovulation induction and corpus luteum development. Ewes underwent four protocols: Long+GnRH (n = 11) with vaginal sponge (60 mg MAP) for 12 days along with 300 IU of eCG on day 12 and 0.025 mg of GnRH 27 h after sponge removal; Long (n = 10) with vaginal sponge for 12 days along with 300 IU of eCG on day 12; Short GnRH (n = 10) with vaginal sponge for 7 days along with 37.5 μg of D-cloprostenol on day 5 and 300 IU of eCG on day 7, plus 0.025 mg of GnRH used 27 h after sponge removal; and Short (n = 10) with vaginal sponge for 7 days. D-cloprostenol (37.5 μg) was administered on day 5 and eCG (300 IU) was administered on day 7.Ovulation was evaluated 52, 56, 60, 66, 72, 76 h after sponge removal. Blood was collected twelve days after sponge removal to measure progesterone concentration. On this same day, the corpus luteum was measure and counted. When GnRH was used, all ewes ovulated, while 70 and 80% of ewes ovulated in protocols that had not received GnRH (Long and Short, respectively). The GnRH accelerated ovulation (P< 0.05) in relation to sponge removal in both protocols and induced ovulation in approximately 28 h. The GnRH Was effective in inducing ovulation without decreasing the corpus luteum volume and progesterone concentration.(AU)

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This study was done to evaluate the efficiency of GnRH along with long-term and short-term synchronization protocols on ovulation induction and corpus luteum development. Ewes underwent four protocols: Long+GnRH (n = 11) with vaginal sponge (60 mg MAP) for 12 days along with 300 IU of eCG on day 12 and 0.025 mg of GnRH 27 h after sponge removal; Long (n = 10) with vaginal sponge for 12 days along with 300 IU of eCG on day 12; Short GnRH (n = 10) with vaginal sponge for 7 days along with 37.5 μg of D-cloprostenol on day 5 and 300 IU of eCG on day 7, plus 0.025 mg of GnRH used 27 h after sponge removal; and Short (n = 10) with vaginal sponge for 7 days. D-cloprostenol (37.5 μg) was administered on day 5 and eCG (300 IU) was administered on day 7.Ovulation was evaluated 52, 56, 60, 66, 72, 76 h after sponge removal. Blood was collected twelve days after sponge removal to measure progesterone concentration. On this same day, the corpus luteum was measure and counted. When GnRH was used, all ewes ovulated, while 70 and 80% of ewes ovulated in protocols that had not received GnRH (Long and Short, respectively). The GnRH accelerated ovulation (P< 0.05) in relation to sponge removal in both protocols and induced ovulation in approximately 28 h. The GnRH Was effective in inducing ovulation without decreasing the corpus luteum volume and progesterone concentration.

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The present study evaluated the effect of the type of norgestomet ear implant (new vs. used) on the ovarian follicular response (experiment 1) and pregnancy per artificial insemination (AI) (P/AI; experiment 2) of beef heifers subjected to an estradiol plus progestin timed artificial insemination (TAI) program. In experiment 1, 57 cyclic beef heifers were randomly assigned to one of two groups according to the type (new or previously used for 9 days) of norgestomet ear (NORG) implant. At the time of NORG implant insertion, the heifers were treated with 2 mg of intramuscular estradiol benzoate. Eight days later, the NORG implants were removed, and the heifers received an intramuscular administration of 150 µg of d-cloprostenol, 300 IU of equine chorionic gonadotropin, and 0.5 mg of estradiol cypionate. The heifers had their ovaries scanned every 12 hours from the time of NORG implant removal to 96 hours after verifying the occurrence and timing of ovulation. No difference (P = 0.89) was observed in the ovulation rates between the two treatments (new = 80.0%; 24/30 vs. used = 81.5%; 22/27). However, the heifers treated with a used NORG implant had (P = 0.04) higher proportion (36.4%; 8/22) of early ovulation (between 36 and 48 hours after NORG implant removal) compared with the heifers treated with a new NORG implant (8.3%; 2/24). In experiment 2, at the beginning of the synchronization protocol, 416 beef heifers were randomly assigned into two groups, as described in the experiment 1. Two days after the NORG implant removal, the heifers were reassigned to be inseminated at 48 or 54 hours after NORG implant removal. There was an interaction (P = 0.03) between the type of NORG implant and the timing of TAI on P/AI. The timing of insemination only had an effect (P = 0.02) on the P/AI when the heifers were treated with a used NORG implant [(TAI 54 hours = 41.9% (44/105) vs. TAI 48 hours = 58.6% (58/99)]. In conclusion, beef heifers synchronized with a used NORG implant plus estradiol exhibited a higher proportion of earlier ovulations, and TAI in these heifers should be performed 48 hours after removal of used NORG implants.

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Background: Progesterone and synthetic progestogens are used to prepare the uterus for pregnancy, and for the hypothalamus, pituitary and ovaries to respond to endogenous and exogenous gonadotropins. The object of this work was to check serum progesterone concentrations in ovariectomised cows, to determine pharmacokinetics of MAD-4 ® product. Materials, Methods & Results: A group of eigth Braford cows was divided into two groups, in two experiments. In experiment I, both groups received 250 mg of progesterone by different routes of application: intramuscular or subcutaneous. In experiment II, subcutaneous application was used in both groups, the differentiation of the treatments lying in the concentration of progesterone: treatment 2 received 250 mg progesterone and treatment 3 was administered 375 mg of progesterone. In the first 24 h samples were collected in intervals of 6 hours, then every 24 h up to 192 h (day 8). In experiment I there was a significant difference (P < 0.05) at 96 h, showing greater concentration in treatment 2 compared to treatment 1 (1.54 ng/mL vs. 0.48 ng/ mL, respectively). In experiment II, in the measures undertaken at 144 h, 168 h and 192 h with significant difference (P < 0.05), concentrations of progesterone in treatment 2 were lower when compared to treatment 3 (0.79 ng/mL vs. 1.63 ng/mL, 0.66 ng/ mL vs. 1.36 ng/mL and 0.49 ng/mL vs. 1.11 ng/mL respectively for hours and treatments). Due to the fact that the types of progestogens and doses used to control the estrous cycle in cattle may be less effective than endogenous progesterone (a corpus luteum) with respect to suppression of LH, the high frequency of LH pulses results in development of “persistent” follicles containing aged eggs of low fertility. In this study, the application of 250 mg of intramuscular and subcutaneous long action injectable progesterone elevated progesterone serum concentration above 1 ng/mL. Subcutaneous application presented levels exceeding 1 ng/mL for a longer time, from 6 to 96 h. This treatment probably suppresses LH pulses temporarily without staying very long in the bloodstream; for this reason it doesnt impair fertility. The same cannot be said in the treatment situation with the application of 375 mg subcutaneous long-action injectable progesterone, because, as long as progesterone was measured (day 8), the concentration remained higher than 1 ng/mL. Discussion: Vaginal silicone implants impregnated with 0.5 g of progesterone, when used for the second time (7 days each time), failed to maintain serum progesterone levels for more than 24 h higher than 1 ng/mL. In this study, treatment with 250 mg intramuscular long-action injectable progesterone showed similar serum concentrations over time, because between 24 and 48 h the levels were below 1 ng/mL. Parenteral routes of administration include, among others, the intramuscular (IM) and subcutaneous (SC). The intramuscular route is characterised by a relatively rapid absorption via the subcutaneous, is characterized by a slower absorption and continuous. Treatment of ovariectomised cows with long-acting injectable progesterone in different doses and by different routes resulted in significantly different serum concentrations at some moments, characteristic of each route of administration and doses used. In this study we can conclude that the seemingly more appropriate treatment is that which makes use of 250 mg of long-acting progesterone, subcutaneously injected, keeping progesterone serum levels higher than 1ng/mL per period of four days.(AU)

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The objective of this study was to determine if exposure of 2 - y ea r - old beef heifers to androgenized steers (AS) for 30 days before the beginning of an estrous synchronization protocol (ESP) and artificial insemination ( AI ) increases the estrous response and pregnancy rate . Hereford x Braford heifers were stratified by body weight and presence of a corpus luteum (CL) and assigned to be 1) e xposed to AS ( EAS ; n = 53) or 2) n o t exposed to AS ( NE ; n = 53) for 30 d ays (D ay 0 = first d ay of exposure) . Proportion s of heifers with a CL on D ay - 7 were 20.6 and 24.5% for EAS and NE , respectively. Ovaries of each heifer were scanned on Days 15 and 30 of the exposure period for a CL . On D ay 30, steers were removed from the EAS heifers and t wo doses of a PG F 2alpha analogue were administered to each heifer 11 d ays apart . Heifers were observed for behavioral estrus for 6 d ys , beginning 48 h after the last PGF 2alph a injection , and inseminated 12 h after estrus detection . More EAS than NE heifers had a CL on D ay 15 ( 5 4.7 and 32.1%, EAS and NE, respectively; P < 0.02) , but there was no difference in the proportion of heifers that had a CL by D ay 30 ( 73.6 and 72 .0 % , EA S and NE, respectively; P = 0.2 ) . There were no difference s between EAS and NE heifers for proportion s that showed estrus ( 66.0 and 67.9 % , EAS and NE, respectively ; P = 0. 8 ), conception rates ( 83 . 0 and 92 . 0 %, EAS and NE, respectively; P = 0. 3 ) and pregnancy rates ( 83 . 0 and 86.5 %, EAS and NE, respectively; P = 0. 6 ) . Exposing 2 - y ea r - old heifers to AS under the conditions of this experiment before an ESP that included a double injection of PGF 2alpha had no effects on estrous response and AI pregnancy rates.(AU)

Assuntos

RESUMO

Background: Progesterone and synthetic progestogens are used to prepare the uterus for pregnancy, and for the hypothalamus, pituitary and ovaries to respond to endogenous and exogenous gonadotropins. The object of this work was to check serum progesterone concentrations in ovariectomised cows, to determine pharmacokinetics of MAD-4 ® product. Materials, Methods & Results: A group of eigth Braford cows was divided into two groups, in two experiments. In experiment I, both groups received 250 mg of progesterone by different routes of application: intramuscular or subcutaneous. In experiment II, subcutaneous application was used in both groups, the differentiation of the treatments lying in the concentration of progesterone: treatment 2 received 250 mg progesterone and treatment 3 was administered 375 mg of progesterone. In the first 24 h samples were collected in intervals of 6 hours, then every 24 h up to 192 h (day 8). In experiment I there was a significant difference (P < 0.05) at 96 h, showing greater concentration in treatment 2 compared to treatment 1 (1.54 ng/mL vs. 0.48 ng/ mL, respectively). In experiment II, in the measures undertaken at 144 h, 168 h and 192 h with significant difference (P < 0.05), concentrations of progesterone in treatment 2 were lower when compared to treatment 3 (0.79 ng/mL vs. 1.63 ng/mL, 0.66 ng/ mL vs. 1.36 ng/mL and 0.49 ng/mL vs. 1.11 ng/mL respectively for hours and treatments). Due to the fact that the types of progestogens and doses used to control the estrous cycle in cattle may be less effective than endogenous progesterone (a corpus luteum) with respect to suppression of LH, the high frequency of LH pulses results in development of “persistent” follicles containing aged eggs of low fertility. In this study, the application of 250 mg of intramuscular and subcutaneous long action injectable progesterone elevated progesterone serum concentration above 1 ng/mL. Subcutaneous application presented levels exceeding 1 ng/mL for a longer time, from 6 to 96 h. This treatment probably suppresses LH pulses temporarily without staying very long in the bloodstream; for this reason it doesn’t impair fertility. The same cannot be said in the treatment situation with the application of 375 mg subcutaneous long-action injectable progesterone, because, as long as progesterone was measured (day 8), the concentration remained higher than 1 ng/mL. Discussion: Vaginal silicone implants impregnated with 0.5 g of progesterone, when used for the second time (7 days each time), failed to maintain serum progesterone levels for more than 24 h higher than 1 ng/mL. In this study, treatment with 250 mg intramuscular long-action injectable progesterone showed similar serum concentrations over time, because between 24 and 48 h the levels were below 1 ng/mL. Parenteral routes of administration include, among others, the intramuscular (IM) and subcutaneous (SC). The intramuscular route is characterised by a relatively rapid absorption via the subcutaneous, is characterized by a slower absorption and continuous. Treatment of ovariectomised cows with long-acting injectable progesterone in different doses and by different routes resulted in significantly different serum concentrations at some moments, characteristic of each route of administration and doses used. In this study we can conclude that the seemingly more appropriate treatment is that which makes use of 250 mg of long-acting progesterone, subcutaneously injected, keeping progesterone serum levels higher than 1ng/mL per period of four days.

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