This study aimed to evaluate the effect of temporary suckling interruption associated with the male effect on reproductive performance of pluriparous Santa Inês ewes. The females were kept apart from the males for 60 days and then randomly distributed into three treatments associated with the male effect (DT0, DT24 and DT48); in DT0, there was no suckling interruption; in DT24, suckling was interrupted for 24 hours, and in DT48, sucking was interrupted for 48 hours. Estrous distribution was observed within 31 (DT0), 27 (DT24) and 38 (DT48) days of the breeding season. Estrous synchronization up to the 5th day of the mating season was observed in 15% (DT0), 30% (DT24) and 25% (DT48) of the females, with no difference among treatments. Estrous percentages were 90% (DT0), 100% (DT24) and 100% (DT48), with no difference among treatments. Pregnancy rates were 38.4% (DT0), 60.0% (DT24) and 45.0% (DT48) with no difference among treatments. Prolificacy was 1.43 (DT0), 1.17 (DT24) and 1.22 (DT48) and did not differ between treatments. In conclusion, temporary suckling interruption associated with the male effect is efficient to induce estrous but not to synchronize estrous or increase the pregnancy rates and prolificacy of Santa Inês ewes during a 45-day breeding season.Keywords: anestrous, biostimulation, reproduction, sheep. EFEITO MACHO ASSOCIADO AO DESMAME TEMPORÁRIO NO DESEMPENHO REPRODUTIVO DE OVELHAS SANTA INÊSRESUMO: O estudo teve como objetivo avaliar o efeito do desmame temporário associado ao efeito macho sobre o desempenho reprodutivo de ovinos Santa Inês. As fêmeas foram mantidas distantes dos machos por 60 dias e aleatoriamente distribuídas em três tratamentos associados ao efeito macho (DT0, DT24 e DT48), no qual em DT0, não houve interrupção da amamentação; em DT24, amamentação interrompida por 24 horas e em DT48, interrupção da amamentação por 48 horas. Distribuição de estro foi observada em 31 (DT0), 27 (DT24) e 38 (DT48) dias da estação de monta. Sincronização de estro até o quinto dia da estação de monta foi observada em 15% (DT0), 30% (DT24) e 25% (DT48) das fêmeas, não havendo diferença entre os tratamentos. Percentagens de estro foram de 90% (DT0), 100% (DT24) e 100% (DT48), não havendo diferença entre os tratamentos. As taxas de prenhez foram de 38,4% (DT0), 60,0% (DT24) e 45,0% (DT48), sem diferença entre os tratamentos. A prolificidade foi de 1,43 (DT0), 1,17 (DT24) e 1,22 (DT48), e não diferiu entre os tratamentos. Em conclusão, o desmame temporário associado ao efeito macho é eficiente na indução do estro, embora não seja eficiente na sincronização de estros e não aumente as taxas de gestação e prolificidade das ovelhas Santa Inês durante uma estação de monta de 45 dias.Palavras-chave: anestro, bioestimulação, ovinos, reprodução.

The aim of this study was to compare testosterone concentration, body weight, scrotal circumference and age to penis detachment from days 30 to 240 in young Boer goat males (n = 22) born during the dry (n = 11) and the rainy (n = 11) seasons. In the dry season the parameters varied as follows: body weight from 3.7 ± 1.1 to 34.0 ± 4.7 kg, scrotal circumference from 7.9 ± 0.8 to 25.7 ± 2 cm, and testosterone concentration from 259.4 ± 172.4 to 4613.4 ± 2892 pc/mL. In the rainy season parameters varied as follows: body weight from 9.7 ± 2.3 to 28.1 ± 6.9 kg, scrotal circumference from 9.5 ± 1.5 to 22.0 ± 3.0 cm and testosterone from 521.9 ± 311.3 to 3417.9 ± 2021.8 pc/mL. At three months of age, 70% of animals born during the rainy season presented with penis detachment, compared to 67.6% of animals born during the dry season at five months of age. Penis detachment occurred in all males at four and seven months for animals born in the rainy and dry seasons, respectively. There was a positive correlation between testosterone concentration and body weight in the dry (r = 0.30) and rainy (r = 0.43) seasons, between testosterone and scrotal circumference in the dry (r = 0.42) and rainy (r = 0.52) seasons, and between body weight and scrotal circumference in the dry (r = 0.93) and rainy (r = 0.88) seasons. The animals born during the rainy season showed earlier development in all the evaluated parameters than animals born during the dry season. It was found that scrotal circumference is directly correlated to body weight and testosterone concentration.

The study was aimed to test the effect of the separation distance between males and females during the preconditioning period on the reproductive performance of Santa Inês ewes after the male effect. Santa Inês ewes were kept at distances of 3000 m (T1), 3 m (T2), and 300 m (T3) from rams for 60 days before starting 45-day mating seasons during the dry period (DP) and rainy periods (RP). Mating events were observed daily at 6:00 h and 16:00 h by trained personnel for one hour intervals. Estrous were scored as synchronized when observed until day 5 after breeding season start. Pregnancy diagnosis was performed by ultrasonography. In the DP, the first estrous averaged at 15.45±10.36 (T1), 9.25±6.41 (T2) and 13.05±10.24 (T3) days and in RP was 8.73±5.84 (T1), 9.30±5.62 (T2) and 6.10±5.66 (T3) days. All females cycled during both DP and RP. Estrous synchronization occurred in 20% of the females during DP (T1: 30%, T2: 15%, and T3: 15%). In the RP, estrous synchronization occurred in 40% of all females (T1: 30%, T2: 35%, and T3: 45%). The pregnancy rates in DP and RP were T1: 85%, T2: 80%, and T3: 75%. The results show that the male effect can be obtained simply by avoiding physical contact between males and females throughout the year under tropical conditions.

The work described here aimed to verify the efficiency of different extenders for cryopreservation of equine semen using sperm motility and acrosin activity as spermatic parameters. The semen was fractioned into two equal parts and resuspended in an 11% lactose solution in a 1:1 proportion, where it remained for 20 minutes at room temperature. The semen was centrifuged at 600 g for 10 minutes, and after the second centrifugation, each pellet received the freezing extender (Merck or Zorlesco) and was loaded into 4 mL straws. Each straw was placed in liquid nitrogen vapor steam for 15 minutes and further immersion in liquid nitrogen at -196°C for long-term storage. After thawing, semen samples were initially evaluated for sperm motility, both total and progressive, and acrosin activity. Moreover, semen was incubated at 37°C and further assessed at 60 and 120 minutes in a thermoresistance test (TRT) for sperm motility and acrosin activity. Immediately after thawing, both progressive and total motility, and acrosin activity were lower (p < 0.05) in thawed semen than in fresh semen. During the TRT, total sperm motility and acrosin activity after 60 minutes were lower (p < 0.05) than those obtained after thawing. Similarly, total sperm motility and acrosin activity were lower (p < 0.05) after 120 minutes than at 60 minutes of the TRT. The analysis of motility and acrosin activity allowed the conclusion that both extenders have a similar capacity to preserve the integrity of sperm cells subject to freezing and thawing.

The aim of this study was to monitor early gestation in Santa Ines ewes by ultrasound in order to determine embryo and foetal loss, and to identify foetal sex. Ewes (n = 132) were submitted to controlled natural mating. For the purpose of pregnancy diagnosis and embryo monitoring we used transrectal ultrasound with a linear transducer (6.0 and 8.0 MHz). Pregnancy was diagnosed on day 30. On day 35 ultrasound examination was performed to determine embryo viability or loss. On days 40, 50 and 60 ultrasound examination was used to monitor foetal loss and to determine foetal sex, through identification of the genital tubercle or any external genital structure. Out of 118 pregnant ewes, 76 (64.4%) presented single pregnancy and 42 (35.6%) multiple pregnancy. Embryonic deaths occurred in 10.0% of the 160 monitored embryos: 5.6% (9/160) occurred during the embryonic phase and 4.4% (7/160) during the foetal phase, with no significant difference between them. Embryo loss was significantly lower in single pregnancies (3.9%, 3/76) compared to multiple pregnancies (15.5%, 13/84). Sexing accuracy on day 40 was significantly lower than on day 60. There was no difference between days 40 and 50, and between days 50 and 60. This study on Santa Ines sheep shows that ultrasound is a highly effective method for diagnosis of early pregnancy, determination of embryo and foetal loss, as well as foetal sexing after day 50 of pregnancy.