Use of PG2α on the puerperio to reduce the pos-partum anestrous of continuos or controlled suckling goats

Trabalho extraído da Dissertação de Mestrado do primeiro autor apresentado ao Programa de Pós-Graduação em Ciência Veterinária da Universidade Federal Rural de Pernambuco.Objetivou-se estudar os efeitos da administração da PGF2α sobre o período de anestro pós-parto de oitenta cabras, em aleitamento contínuo ou controlado, criadas em sistema semi-extensivo com acesso à água e sal mineral ad libitum. As fêmeas, com idade entre dois e seis anos, foram aleatoriamente distribuídas em três grupos experimentais (GI, GII, GIII). As do GI (n = 30) receberam, na musculatura vulvar, 250μg de PGF2α no 6o e 12o dias após o parto. As do GII (n = 30) foram tratadas, pela mesma via e com a mesma dose de PGF2α, no 6o, 7o, 8o, 9o e 10o dias do pós-parto, e as do GIII (n = 20) serviram como controle. Realizou-se a detecção do estro por rufião com auxílio de pessoal habilitado e efetuaram-se as coberturas com reprodutores de fertilidade comprovada. Analisaramse os dados através da ANOVA e do cálculo do erro-padrão da diferença entre proporções. Não se verificou diferença (P > 0,05) das porcentagens de estro entre os três grupos experimentais; todavia, a duração média do anestro pósparto foi significativamente reduzida (P 0,05) nas porcentagens de prenhez entre os diferentes grupos. Os dados obtidos permitem concluir que a administração da PGF2α no início do puerpério é eficiente para reduzir o período de anestro pósparto, especialmente nas fêmeas em aleitamento controlado; contudo, não exerce influência sobre a fertilidade de cabras SRD com aptidão para produção de carne. ____________________________________________________________________________ ABSTRACTThis work aimed to study the effect of PGF2α administration on anestrous post-partum period in 80 goats, with continuos or controlled suckled, rised in semiextensive system with water and mineral salt ad libitum. The females, with age between two and six years, were randomly distributed in three groups (GI, GII, GIII). The females of GI (n = 30) received 250μg of PGF2α in vulvar muscle on days 6th and 12th after delivery. The females of GII (n = 30) received the same treatment of Group I, but every day from days 6th to 10th after delivery. The GIII (n = 20) was the control group. The estrous detection was made by using teasers and the mating with bucks with confirmed fertility. The obtained data were analyzed by ANOVA and by analysis of standard errors of difference among proportions. Difference in the occurrence of estrous among the three experimental groups was not observed (P > 0.05), however the average time of post partum anestrous was significantly reduced (P 0.05) on pregnant percentages among the different groups. It may be concluded that the administration of PGF2α in the beginning of puerperium in caprine is efficient to reduce the anestrous pos-partum period, specially in females controlled suckled; however do not influence the fertility in meat goats

Estrus synchonization with prostaglandin F2α compared to progestogen treatment associated with equine chorionic gonadotropin (eCG) in Santa Inês breed ewes reared in Federal District, Brazil

Este estudo teve por objetivo comparar o uso de um análogo da PGF2α à associação de progestágeno (MAP) com gonadotrofina coriônica equina (eCG) na sincronização do estro em ovelhas da raça Santa Inês. Foram utilizadas 38 fêmeas ovinas submetidas a dois protocolos de sincronização de estro, com os seguintes protocolos: PGF2α (duas doses de 0,53 mg de D-cloprostenol com nove dias de intervalo) e protocolo MAP+eCG (pessário intravaginal com 50 mg de acetato de medroxiprogesterona por doze dias e no momento da remoção do dispositivo aplicação de 250 UI de eCG, IM). Submeteram-se as ovelhas aos diferentes protocolos, com intervalo de dois ciclos estrais. Procedeu-se a uma ultrassonografia transretal no último dia do protocolo, para avaliação do diâmetro do maior e do segundo maior folículo, e à coleta de sangue no dia sete do ciclo estral, para avaliação da concentração sérica de P4. Exame laparoscópico foi realizado no dia 11, após o fim dos protocolos, para contagem de corpos lúteos. Para os parâmetros taxa de sincronização, diâmetro do maior e do segundo maior folículo, período do final do protocolo ao estro e taxa de ovulação, não se observaram diferenças entre os mesmos. Foi observado que o protocolo MAP+eCG produziu concentrações séricas de P4 maiores do que o protocolo PGF2α (3,9 e 2,8 ng/ mL, respectivamente, P<0,05). Nas condições do presente estudo, embora o protocolo MAP+eCG tenha apresentado superioridade em relação à concentração sérica de P4, o protocolo PGF2α foi tão eficiente quanto aquele em sincronizar o estro. __________________________________________________________________________________________ ABSTRACTThe aim of this study was to compare two protocols of estrus synchronization in Santa Inês ewes. Thirty-eight ewes were randomly divided into two groups of estrus synchronization: protocol PGF2α (two doses of 0.530 mg of PGF2α, nine days apart) and protocol MAP+eCG (intravaginal sponge impregnated with medroxyprogesterone acetate, for 12 days, and then an injection of 250 IU of eCG). The experiment was in a cross-over design, two estrous cycles apart. On the final day of protocol, a transrectal ultrasound examination was carried out to measure the size of the largest and second largest ovarian follicles and on day 7 of estrous cycle blood was collected to measure serum P4 concentration. Laparoscopy was carried out on day 11 after the end of protocols to count corpora lutea. Synchronization rate, size of largest and second largest ovarian follicles, interval between the end of the protocol to estrus and ovulation rate did not differ between protocols. Ewes synchronized with MAP+eCG had greater serum P4 concentrations than ewes synchronized with PGF2α (3.9 and 2.8 ng/mL, respectively, P<0.05). Based on the results, it may be concluded that, although the protocol MAP+eCG was superior in inducing higher serum concentration of P4, the protocol PGF2α was equivalent regarding estrus synchronization

Spermatic and seminal evaluation in Young Boer goats born in the rainy and dry season

Este trabalho objetivou determinar motilidade, turbilhonamento, vigor, defeitos maiores e menores dos espermatozoides de caprinos da raça Boer durante a estação chuvosa (n = 11) e seca (n = 11). Na estação chuvosa, a concentração espermática variou de 0,90 ± 1,46 x 109/mL a 2,7 x 109/mL, a motilidade progressiva de 16,0% a 62,0%, o turbilhonamento de 0,3 a 2,6 , vigor de 1,1 a 2,8 , defeitos maiores de 18,3% a 3% e menores de 16,1% a 3,4%. Na estação seca, a concentração espermática variou de 0,96 x 109/mL a 2,15 x 109/mL, a motilidade progressiva de 35,4% a 64,1%, o turbilhonamento de 1,7 a 3,1, vigor de 2,0 a 3,0, defeitos maiores de 16,9% a 4,2% e menores de 17,5% a 3,2%. Foi registrada correlação positiva (P < 0,05) entre motilidade espermática vs turbilhonamento espermático, respectivamente, para a estação chuvosa e seca, motilidade espermática vs vigor espermático bem como negativa entre motilidade progressiva vs defeitos maiores dos espermatozoides e entre motilidade progressiva e defeitos menores dos espermatozoides. Dessa forma, pode-se concluir que machos caprinos da raça Boer nascidos na estação seca têm atraso de três meses do início da maturidade sexual em comparação àqueles nascidos na estação chuvosa. __________________________________________________________________________________________ ABSTRACTThis study had the objective to distinguish spermatic and seminal parameters in animals born during the dry (n=11) and rainy (n=11) seasons. In the rainy season, the spermatic concentration ranging from 0.90 to 2.7 x 109/mL, the progressive motility from 16.0% to 62.0%, the mass movement from 0.3 to 2.6, vigor from 1.1 to 2.8, major sperm defects of 18.3% to 3 % and minor sperm defects from 16.1% to 3.4% . In the dry season, the spermatic concentration varied from 0.96 to 2.15 x 109/mL, the progressive motility from 35.4% to 64.1%, the mass movement form 1.7 to 3.1, vigor from 2.0 to 3.0, major sperm defects from 16.9% to 4.2% and minor sperm defects from 17.5% to 3.2%. It was observed positive correlation between spermatic motility versus spermatic mass movement, spermatic motility versus spermatic vigor as well as a negative correlation between motility versus major sperm defects of the spermatozoa and between motility and spermatozoa smaller defects respectively, in the rainy and dry seasons. Based on these results we conclude that Boer male goats born in dry season have sexual retardation of three months in comparison to those born in the rainy station

Fetal sexing by ultrasonography identifying the genital tubercle or external genitalia of American Alpine goats

Neste trabalho objetivou-se diagnosticar precocemente o sexo de fetos caprinos da raça Alpina Americana através da ultra-sonografia, identificando-se a posição final do tubérculo genital (TG) ou visualizando-se as estruturas anatômicas da genitália externa, bem como avaliar a acurácia da sexagem fetal resultante de exame único ou repetido. No Grupo I (GI), identificou-se o sexo levando-se em consideração o posicionamento final do TG, e no Grupo II (GII) a presença de estruturas anatômicas da genitália externa. Realizaram-se os exames por via transretal com aparelho de ultra-som (240 Parus - Pie Medical) equipado com transdutor linear de 6 e 8 MHz. No GI, 52 fetos de 32 matrizes foram monitorados em intervalos de doze horas, do 40º ao 60º dia de gestação. No GII, submeteram-se 34 fetos de 24 matrizes com gestação entre 45 e 70 dias a exame único. A acurácia da sexagem no GI foi de 100% na gestação simples, 87,5% na dupla e 66,7% na tríplice, sendo registrada diferença significativa (P 0,05) entre ambas. A migração do TG genital ocorreu, em média, no 46,4 ± 2,1 dia de gestação. Os resultados permitem concluir que a ultra-sonografia é um método apropriado para diagnosticar precocemente o sexo fetal através da identificação da posição final do TG ou da visualização de estruturas anatômicas da genitália externa e que exames repetidos não aumentam a acurácia da sexagem fetal na gestação múltipla. __________________________________________________________________________________________ ABSTRACTThe aim of this study was to diagnostic previously the gender of American Alpine fetuses by ultrasonography identifying the final position of the genital tubercle (GT) or viewing the anatomical structures of external genitalia, as well as to evaluate the accuracy of fetal sexing by single or repeated exams. In Group I (GI), the gender was defined by the final position of the GT and in Group II (GII) by the anatomical structures of external genitalia. The exami¬nations were carried out with an ultrasound device by via transrectal equipped with a linear transducer with 6.0 and 8.0 MHz. In GI, 52 fetuses of 32 goats were monitored each 12 hours, from 40th to the 60th day of pregnancy. In GII, the examination was performed only once in 34 fetuses of 24 goats with pregnancy between 45 and 70 days. The accuracy in GI was 100% in single, 87.5% in twin and 66.7% in triple pregnancy, with significant difference (P 0.05) between single and twin pregnancies. The final migration of GT occured on the 46.4 ± 2.1 days of pregnancy. The results allow to conclude that ultrasonography is a suitable method to early diagnostic the fetal sex by visualization of final position of GT or by identification of external genitalia structures and that repeated exams did not increase the accuracy of fetal sexing on the multiple pregnancy

Ultrasonographic evaluation of embryo-fetal development of Saint Ines breed of ewes

Avaliou-se, por ultra-sonografia transretal, o desenvolvimento embrionário-fetal de ovinos Santa Inês, identificando o dia da primeira visualização dos principais parâmetros da gestação de sessenta ovelhas entre o 15° e o 45° dia de gestação. A identificação mais precoce e mais tardia dos parâmetros avaliados ocorreu entre os dias 15 e 19 (16,7 ± 1,3) da gestação para líquido intra-uterino, 16 e 22 (18,6 ± 1,4) para vesícula embrionária, 18 e 26 (22,8 ± 1,9) para embrião, 20 e 29 (25,1 ± 2,0) para placentomas, 24 e 29 (25,9 ± 1,4) para batimento cardíaco, 24 e 32 (27,4 ± 1,8) para membrana amniótica, 30 e 37 (33,4 ± 2,2) para diferenciação entre cabeça e tronco, 30 e 38 (34,2 ± 2,0) para movimento do feto, 32 e 39 (35,1 ± 1,5) para cordão umbilical, 34 e 39 (36,7 ± 1,5) para botão dos membros anteriores e posteriores e entre os dias 39 e 43 (40,9 ± 1,2) para globo ocular. Conclui-se que é possível identificar os primeiros sinais de gestação já no 15º dia, todavia, é prudente que o diagnóstico de gestação somente seja emitido a partir do 24º dia, quando é possível visualizar o embrião e seus batimentos cardíacos. __________________________________________________________________________________________ ABSTRACTThis study was evaluated, by transretal ultrasound, the embryonic-fetal development from days 15th to 45th of gestation visualizing the first signs of gestation in 60 Sant Inês ewes. The identification of the earliest and the latest parameters of evaluation were performed between days 15th to 19th (16.7 ± 1.3) of pregnancy for intra-uterine fluid, . embryonic vesicle between days 16th to 22nd (18.6 ± 1.4), embryo between 18th to 26th (22.8 ± 1.9), placentoms between 20th to 29th (25.1 ± 2.0), heartbeat between days 24th to 29th (25.9 ± 1.4), amniotic membrane between 24th to 32nd (27.4 ± 1.8), head and upper body differentiation between 30th to 37th (33.4 ± 2.2), fetus movement between 30th to 38th (34.2 ± 2.0), umbilical cord between 32nd to 39th (35.1 ± 1.5), button of the anterior and posterior members between 34th to 39th (36.7 ± 1.5) and ocular globe between days 39th to 43th (40.9 ± 1.2). It was concluded that the first signs of gestation can be identified as soon as day 15th days of gestation. However, it is wise diagnosing pregnancy after day 24th, when it is possible to visualize the fetus and the heart beat

Induction of Ovulation in Mangalarga Marchador Mares by hCG or GnRH

Background: Induction of ovulation is a key procedure for horse assisted reproduction technologies, such as for artificial insemination (AI) and embryo transfer. The application of hCG remains as the primary ovulation-inducing agent for horse assisted reproduction, but alternatives are in demand to avoid its adverse effects, such as loss of ovulation-inducing efficiency over multiple applications by hCC-antibody production. Despite reports on alternative ovulation-inducing agents, pair-wise comparisons of such agents under similar conditions have been limited. Under such scenario, the work was aimed to determine the efficiency of both hCG and Buserelin at inducing ovulation in Mangalarga Marchador mares raised in the Northeast of Brazil under an AI program.Materials, Methods & Results: Mares were initially selected based on their reproductive performance, the absence of clinical-reproductive alterations and adequate body condition score. Mares in diestrus were randomly distributed in three experimental conditions, received 5 mg of Dinoprost and were monitored daily for estrus detection. After estrus detection, ovaries were monitored by ultrasonography, in 12-h intervals, until the follicle reached 35 mm. At this time-point, ovulation was induced with 0.042 mg of Buserelin endovenously, with 3,000 IU hCG by an intramuscular shot, and control mares received 2 mL of saline solution, also by an intramuscular shot. Both hCG and Buserelin displayed similar efficiencies (P > 0.05) for induction of ovulation and that both agents were effective (P 0.05) from those found in the Control. All ovulations occurred within a 72-h period after treatment. It can be observed that in mares treated with hCG or Buserelin, ovulations occurred both in more mares (P 0.05) between hCG and Buserelin groups, and that pregnancy of mares treated with ovulation-inducing factors was similar to the control.Discussion: The majority of ovulations in mares occurred within initial 48-h after treatment for both hCG and GnRH, suggesting a similar potential for horse assisted reproduction. Both hCG and Buserelin are two commonly used agents for induction of ovulation in mares. As described here, the majority of ovulations occurred within initial 48-h after treatment, a fact which can be attributed to hCG and GnRH activity, since it can happen in intervals from 36 to 48-h after treatment. Pregnancy rates did not differ among groups. These results are under the working hypothesis that hCG and Buserelin would display similar efficiencies on pregnancy rates. Despite the understanding of hCG activity on induction of ovulation due to its high specificity toward LH receptors and results from a direct effect on diminishing estradiol concentration, increasing LH, and further inducing ovulation within 48-h after treatment. In contrast, Buserelin has a similar functional property but acts upon LH synthesis and its release. In conclusion, ovulation in mares can be induced with both hCG and Buserelin, and both ovulation-inducing agents do not affect pregnancy rates

Functional Assessment of Diluent Choice for Semen Cryopreservation from Stallions with High and Low Freezability

Background: fertility rates using horse frozen-thawed semen remain lower than in other livestock species. This fact further suggests that horse semen hold intrinsic sensitivity to cryoinjury that must be investigated. Moreover, there is a substantial influence of genetic factors and diluent choice upon horse cryopreservation outcome. Collectively, these genetic and technical properties of horse semen could be explored to identify factors or conditions that may increase semen viability after freeze-thawing. The aim of this work was to evaluate the effect of diluents Botu-Crio®,Lactose-EDTA®, and INRA-82® on cryopreserved semen from stallions with high (HFA) and low freezability (LFA).Materials, Methods &amp; Results: frozen-thawed semen was evaluated for motility, membrane integrity, and sperm DNA fragmentation using the thermoresistance test (TRT). Comparisons for each parameter were done in a pair-wise fashion between HFA and LFA semen at one-hour intervals during the TRT (0 h - 4 h). Sperm motility in HFA, regardless of the diluent, was larger (P &lt; 0.05) than LFA, both on 0h and 1h. In the 2h evaluation, sperm motility using Botu-Crio® and Lactose-EDTA® was greater (P &lt; 0.05) for HFA. Analysis of sperm membrane integrity was similar between HFA and LFA semen (P &gt; 0.05) at 0 h and 3 h. Sperm DNA fragmentation was lower (P &lt; 0.05) in HFA semen at 0 h and 1 h. Discussion: frozen-thawed semen from stallions of high freezing ability showed greater motility at all analysis, irrespectively of diluent choice, suggesting a strong influence of genetic factors on cryopreservation outcome. Membrane integrity was similar immediately after thawing but did differ later on other TRT time-points, irrespectively of diluent choice. As observed for motility, it was expected that sperm cells of stallions of HFA would show higher membrane integrity than their LFA counterparts. Sperm DNA fragmentation was quite low for both groups, as described in horses. Surprisingly, sperm DNA fragmentation incidence was constant throughout the analysis for both HFA and LFA. It was initially envisioned that increased DNA fragmentation would be found in semen from LFA stallions, since it is caused by multiple origins such as genetic factors. In conclusion, the semen diluent affects horse sperm motility after thawing, particularly from stallions with lower semen freezability

Influence of Male to Female Ratio on Hormone Profiles and Reproductive Performance of Anestrus Postpartum Ewes Subjected to the Male Effect

Background: Complete isolation of genders allows intense estrous induction and synchronization once rams are introduced in ewe flocks at the onset of the breeding season (BS). This management practice, defined as the male effect, results from a neuroendocrine process mediated by pheromones. The male effect is a straightforward procedure to induce estrous in noncycling ewes, but conditions for its use have not been fully explored. Thus, this study aimed to evaluate hormone levels and ovarian activity of postpartum ewes in anestrus which are subjected to the male effect under different male to female ratios.Material, Methods &amp; Results: Pospartum females were selected according to body condition score and cyclicity status. Females were kept apart from males during 30 days at a distance of 10 m. Anestrus and ovulation were determined by P4 measures on days 10, 20 and 30 after isolation from males. After P4 concentration diagnosis, anestrus ewe (n = 99) were subjected to male to ewe ratios (MFR) of 1:20 (MFR20), 1:30 (MFR30) and 1:40 (MFR40). Santa Inês rams  (n = 3) of proven fertility were used. Three females of each group were randomly subjected to blood collection for LH concentration analysis. Ovarian activity was performed by ultrasonography after estrus manifestation in six ewe of each group. Estrus events were observed twice a day during the BS of 35 days, and estrus were considered synchronized when it occured within the initial five days of the BS. Pregnancy diagnosis was performed by ultrasonography on days 35 and 60 after the last mating. All ewe were in a non-cycling condition before BS onset, based upon P4 analysis. After initiation of the BS, P4 concentrations increased for all groups. Irrespectively of male to female ratio, male effect induced LH pre-ovulatory peaks within the initial 26 to 86 h of the BS. Synchronization of estrus reached 50% for MFR20, 40% for MFR30 and 20% for MFR40 for all ewe. Moreover, overall estrus incidence was 100% (MFR20), 90% (MFR30) and 65% (MFR40) within the initial 15 days of the BS. However, incidence of ewe that had repeated estrus events was lower for MFR20 than for MFR30. Follicular growth and number of ovulations was similar between groups. Conception rates on first service was higher than that of second service for MFR20 and MFR30, although there was no difference between services for MFR40. In contrast, overall conception rates, delivery type and prolificacy were similar between groups.Discussion: P4 increased to cyclicity levels after contact between genders, demonstrating the potential of the male effect to induce estrus in non-cycling ewes. Most ewe ovulated within three days after the male effect, possibly due to elevated basal LH levels. Moreover, the LH preovulatory peak varied within groups, possibly due to greater interactions between genders, which ultimately may have led to earlier ovulation anticipation under lower MFR. Estrus parameters were similar between groups, suggesting low or negligible effects of MFR. Ovulatory follicle size and growth and the number of ovulations were similar between all groups; previous reports have suggested that this may be due to a strong effect of their genetic background. Conception rates were higher at first than second services, demonstrating the potential of male effect. In conclusion, male to female ratio affects the efficiency of the male effect to induce and synchronize estrus in ewes under postpartum anestrus, but it does not affect conception rates and prolificacy

Evaluation of Corpus Luteum Vascularization in Recipient Mares by Using Color Doppler Ultrasound

Background: Embryo transfer is one of the most commonly used reproductive biotechnique. The success of embryo transfer is also affected by the synchrony of estrus and ovulation between donor and recipient animals. In horse reproduction, ultrasonography has been used, among other purposes, to diagnose early pregnancy. However, only the color Doppler imaging mode makes it possible to evaluate the vascular architecture and the hemodynamic aspects of the vessels in several organs, especially the corpus luteum. The objective of this study was to evaluate, based on the color Doppler ultrasound, the corpus luteum vascularization and function from recipient mares at embryo transfer timing.Materials, Methods & Results: Mangalarga Machador mares from 5 to 10-year-old and a range of live weights of between 350 to 450 kg were used for this experiment, kept in pasture-based on mombaça grass (Panicum maximum) and were given ad libitum access to water and mineral supplementation. The animals (n = 15) were gynecologically examined and uterine consistency was evaluated by rectal palpation the same operator using an ultrasound system (SonoScape®) with a linear transducer, and operating frequency ranging from 5 to 10 Mhz. The uterine tone was classified between grades 1 and 4 and subjected to ovulation induction. The objective and subjective vascular perfusion of the corpus luteum was evaluated by color Doppler ultrasound on the day of embryo transfer and endometrium. The determination progesterone concentration on the day of the embryo transfer was performed by direct chemiluminescence assay. The arcsine (√P/100) transformation was applied to the percentage data, and the results were expressed as mean (.) ± standard error of the mean (SEM). Further, the assumptions of normality and homoscedasticity were verified, respectively, based on the Shapiro-Wilk and Lilliefors tests. Regarding the parametric and non-parametric variables, were applied, respectively, analysis of variance (ANOVA) followed by Tukey’s test, and the Kruskal-Wallis test followed by Dunn’s test. Pearson’s correlation coefficient was used to evaluate the relationship between the parameters. The statistical program SPSS 16.0 was used to perform the over-mentioned analyses, and a p-value 0.05).Discussion: Mares that later became pregnant showed a higher concentration of progesterone as an outcome of the higher vascularization in the corpus luteum. It can be supported by both the correlation between the progesterone concentration and the corpus luteum vascular perfusion, as well as by the higher values of the vascular perfusion in pregnant mares. Based on the results, it has been concluded that the color Doppler ultrasound evaluation is an accurate tool to determine the corpus luteum vascularization, whether considering the objective or subjective methods. Also, the vascular perfusion is the most efficient parameter to determine both the corpus luteum function and to predict the ability of the recipient mares to maintain pregnancy

ULTRASSONOGRAFIA TRANSRETAL PARA IDENTIFICAR O SEXO FETAL DE CAPRINOS

Procurou-se estabelecer o período para sexar fetos caprinos pela ultrassonografia transretal visibilizando-se as estruturas da genitália externa, sendo que para tal foi monitorado o dia do posicionamento final do tubérculo genital (TG), bem como o dia em que o pênis, a bolsa escrotal, o clitóris e as tetas foram visibilizados. Foram monitorados fetos das raças Boer (n = 36), Parda Alpina (n = 31) e Anglo-nubiana (n = 27), do 40o ao 60o dia de gestação, usando-se transdutor linear de 6,0 e 8,0 MHz. O posicionamento final do TG ocorreu no período de 47,11 ± 1,45 dias, nos machos, e 45,62 ± 1,36 dias, nas fêmeas, e a visibilização das estruturas da genitália externa no período de 49,42 ± 2,20 dias para a bolsa escrotal; 49,37 ± 2,19 dias para o pênis; 49,23 ± 1,75 dias para as tetas e 49,98 ± 2,52 dias para o clitóris. A migração do TG no feto fêmea foi mais precoce (P 0,05) entre as estruturas referentes ao mesmo sexo. Conclui-se que apesar da sexagem de fetos caprinos poder ser efetuada antes do 55o dia de gestação, recomenda-se realizá-la somente após a visibilização das estruturas da genitália externa para uma maior segurança na identificação do sexo. PALAVRAS-CHAVES: Bolsa escrotal, clitóris, pênis, sexagem, tetas