RESUMEN

This study examined the effects of exogenous hCG administration on ovarian function and pregnancy rates in estrous-induced dairy goats during the transition into the breeding season. Eighty-six Toggenburg does received 60 mg of medroxyprogesterone acetate intravaginal sponge for 6 d plus 200 IU of equine chorionic gonadotropin and 30 µg of d-cloprostenol i.m. 24 h before sponge removal, and were then bred for 96 h. Seven days (D7) after first mating the does received either 1 mL of saline (the control group, n = 43) or 300 IU of hCG (the hCG-treated group, n = 43) i.m. Transrectal ovarian ultrasonography (B-mode and color Doppler) was performed on D7, D13, D17, and D21 and ultrasonographic pregnancy detection on D30. Pregnancy rate was higher (P < 0.05) in hCG-treated goats (90.7%; 39/43) than that in control animals (74.4%; 32/43). Accessory luteal structures (ALSs) were detected in 46.5% (20/43) of hCG-treated does. All hCG-treated does that had ALSs and 82.6% of goats without ALS post-treatment remained pregnant. The total luteal area increased (P < 0.05) from D7 to D13 in pregnant animals of both groups, whereas mean vascular area declined (P < 0.05) by D21 in all nonpregnant does. Serum progesterone concentrations increased (P < 0.05) on D21 in pregnant goats of both groups, but they were related to changes in luteal tissue content only in control does throughout the present study. Mean daily numbers of small- and medium-sized antral follicles decreased (P < 0.05) only in pregnant animals of both groups with a decline in medium follicle numbers occurring earlier in hCG-treated (D13) compared with control does (D17). To summarize, a single dose of hCG given on D7 after estrus was followed by a decrease in the number of medium-sized antral follicles in gestating hCG-treated does, induced the formation of ALSs in ~47% of all hCG-treated does, and significantly increased the pregnancy rate in estrous-induced Toggenburg goats in the transition to the breeding season.

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This study was conducted to evaluate effects of two administrations of d-cloprostenol at different intervals to synchronize the time of estrus and ovulation among estrous cyclic goats. In Experiment 1, 32 does were treated with 30 µg d-cloprostenol at 7.5 (T7.5, n = 16) or 11.5-day (T11.5, n = 16) intervals. In Experiment 2, the same treatments were administered and there was AI of the does (T7.5, n = 40 and T11.5, n = 38). In Experiment 1, ultrasonic assessments of ovaries were conducted at the time of the second administration of d-cloprostenol, every 12 h until detection of ovulation, and 7 days after estrous onset to detect the corpora lutea, as well as for pregnancy diagnosis 40 days after AI. In Experiment 1, the estrous response (90.6%, 29/32) was similar (P > 0.05) in both groups. Diameter of the largest follicle at the time of administration of the second dose was larger (P = 0.01) in the T7.5 than T11.5 group (7.0 compared with 5.7 mm), while the values for ovarian variables were similar (P > 0.05). In Experiment 2, the greatest (P < 0.001) synchrony in timing of initiation of estrus in does (T7.5 = 83.3% and T11.5 = 50.0%) occurred after the second day (36-48 h). The pregnancy rate tended (P = 0.0836) to be greater for does in the T7.5 (71.4%, 40/56) than T11.5 (55.6%, 30/54) group. With use of both protocols, there were acceptable estrous synchronization and pregnancy rates in estrous cyclic dairy goats.

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This study evaluated the effect of increasing centrifugal force and reducing centrifugation time and volume in Percoll protocols on ram sperm parameters. Commercial semen of Santa Inês rams were used and five treatments were performed: traditional Percoll and mini-Percoll (MP) techniques (I- 5000 x g, 5min; II- 2500 x g, 5min; III- 1250 x g, 5min; IV- 700 x g, 10min). At post-thawing (PT) and post-selection protocols (0h), samples were assessed for spermatozoa recovery rate, motility, plasma membrane (PM) integrity, sperm capacitation and morphology and incubated at 37 C for 1, 2 and 3h. The sperm recovery rate averaged 9.1±1.4%, and most motility parameters were similar (P> 0.05) among protocols. VCL (µm/s) was higher (P< 0.05) after MP-II, III and IV (66.1±4.5) than traditional Percoll (46.3±4.9). Capacitation status and PM integrity were similar (P> 0.05) among treatments. For the first time, we have demonstrated the reduction of the gradient volume and centrifugation time associated with an increase on centrifugation force at Percoll can be successfully used for frozen-thawed ram sperm selection. MP may be used instead of traditional Percoll, decreasing costs and semen handling time.(AU)

O presente estudo avaliou o efeito do aumento da força de centrifugação, bem como da redução do tempo de centrifugação e do volume do gradiente de Percoll em diferentes protocolos nos parâmetros espermáticos de ovinos. Foi utilizado sêmen comercial de carneiros da raça Santa Inês, e cinco tratamentos foram realizados: Percoll tradicional e quatro técnicas de mini-Percoll (I- 5000 x g, 5min; II- 2500 x g, 5min; III- 1250 x g, 5min; IV- 700 x g, 10min). Após o descongelamento e a seleção espermática em cada técnica utilizada (0h), amostras foram avaliadas quanto à taxa de recuperação espermática, motilidade, integridade de membrana plasmática, capacitação e morfologia. Ao final, foram incubadas a 37 ºC por uma, duas e três horas. A taxa de recuperação média (9,1±1,4%) e a maioria dos parâmetros de motilidade foram similares (P>0,05) entre os tratamentos. VCL foi maior (P<0,05) após MP-II, III e IV (66,1±4,5) quando comparados ao Percoll tradicional (46,3±4,9). O status da capacitação e a integridade de membrana foram similares (P>0,05) entre os tratamentos. Pela primeira vez, foi demonstrado que a redução do volume do gradiente utilizado e do tempo de centrifugação, associada com o aumento da força de centrifugação nos protocolos de Percoll, pode ser usada com sucesso na seleção espermática de sêmen congelado de ovinos. O mini-Percoll pode ser utilizado em alternativa à técnica de Percoll tradicional, diminuindo custos e tempo de manipulação do sêmen durante a técnica.(AU)

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RESUMEN

This study evaluated the effect of increasing centrifugal force and reducing centrifugation time and volume in Percoll protocols on ram sperm parameters. Commercial semen of Santa Inês rams were used and five treatments were performed: traditional Percoll and mini-Percoll (MP) techniques (I- 5000 x g, 5min; II- 2500 x g, 5min; III- 1250 x g, 5min; IV- 700 x g, 10min). At post-thawing (PT) and post-selection protocols (0h), samples were assessed for spermatozoa recovery rate, motility, plasma membrane (PM) integrity, sperm capacitation and morphology and incubated at 37 C for 1, 2 and 3h. The sperm recovery rate averaged 9.1±1.4%, and most motility parameters were similar (P> 0.05) among protocols. VCL (µm/s) was higher (P< 0.05) after MP-II, III and IV (66.1±4.5) than traditional Percoll (46.3±4.9). Capacitation status and PM integrity were similar (P> 0.05) among treatments. For the first time, we have demonstrated the reduction of the gradient volume and centrifugation time associated with an increase on centrifugation force at Percoll can be successfully used for frozen-thawed ram sperm selection. MP may be used instead of traditional Percoll, decreasing costs and semen handling time.(AU)

O presente estudo avaliou o efeito do aumento da força de centrifugação, bem como da redução do tempo de centrifugação e do volume do gradiente de Percoll em diferentes protocolos nos parâmetros espermáticos de ovinos. Foi utilizado sêmen comercial de carneiros da raça Santa Inês, e cinco tratamentos foram realizados: Percoll tradicional e quatro técnicas de mini-Percoll (I- 5000 x g, 5min; II- 2500 x g, 5min; III- 1250 x g, 5min; IV- 700 x g, 10min). Após o descongelamento e a seleção espermática em cada técnica utilizada (0h), amostras foram avaliadas quanto à taxa de recuperação espermática, motilidade, integridade de membrana plasmática, capacitação e morfologia. Ao final, foram incubadas a 37 ºC por uma, duas e três horas. A taxa de recuperação média (9,1±1,4%) e a maioria dos parâmetros de motilidade foram similares (P>0,05) entre os tratamentos. VCL foi maior (P<0,05) após MP-II, III e IV (66,1±4,5) quando comparados ao Percoll tradicional (46,3±4,9). O status da capacitação e a integridade de membrana foram similares (P>0,05) entre os tratamentos. Pela primeira vez, foi demonstrado que a redução do volume do gradiente utilizado e do tempo de centrifugação, associada com o aumento da força de centrifugação nos protocolos de Percoll, pode ser usada com sucesso na seleção espermática de sêmen congelado de ovinos. O mini-Percoll pode ser utilizado em alternativa à técnica de Percoll tradicional, diminuindo custos e tempo de manipulação do sêmen durante a técnica.(AU)

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