ABSTRACT The objective with this study was to evaluate the libido and sexual behavior of Pantaneiro stallions in Brazil in two periods, the rainy and dry seasons. Their sexual behavior was evaluated during mating with mares in estrus, and the libido was scored for statistical analysis. The reaction time and time to mount and ejaculate were 78.1±64.6 s and 289.0 s, respectively. The most relevant events of sexual behavior observed in the Pantaneiro stallions were mounting without erection, mounting without ejaculation, smelling, and vocalizing. In general, the season did not affect the libido of stallions. Even with the high temperatures and humidity, which could cause thermal stress, the stallions showed good libido score during most of evaluations, with some individual differences. Pantaneiro stallions are able to breed mares during the entire year and could facilitate the breeding management to raise the number of Pantaneiro horses of the herds and optimize the use of the stallions during the breeding season, with more females per male.

Abstract The aim of this study was to analyze the effects of genetic group and sex on residual feed intake, performance, testicular size, carcass and morphometric traits in Santa Ines purebred and Dorper ´ Santa Ines crossbred lambs. A total of 32 lambs, with initial body weight of 18±3.7 kg were used. Analysis of variance, considering the interaction between sex and genetic group of all the traits were performed. Crossbred females (-0.018±0.06) and purebred males (-0.018±0.05) were more efficient (p<0.001) in residual feed intake than crossbred males (0.018±0.04) or purebred females (0.018±0.04). The most efficient animal in residual feed intake consumed 37.9% less feed (1.179 kg/day) than the least efficient animal (1.899 kg/day). Crossbred, when compared to purebred, showed higher values for body weight, average daily gain, testicle size, carcass traits; had greater muscle accumulation, were more compact and with more aptitude to beef. Purebred were taller, but with lower body length and thoracic perimeter than crossbred. Males had greater muscle accumulation, were more compact and with more aptitude to meat. Crossing of native (Santa Ines) with exotic breed (Dorper) is an alternative to align efficiency in feed use, testicular size, compactness, aptitude for meat and ability for muscle accumulation.

Resumen Antecedentes: El actual manejo reproductivo en poblaciones de bovinos de élite incluye la utilización de tecnologías de reproducción asistida (ARTs) con el fin de obtener mayor ganancia genética. Sin embargo, el uso inadecuado de las ART puede llevar a la pérdida de diversidad genética en los descendientes. Objetivo: Evaluar la diversidad genética en poblaciones de vacas de élite utilizadas en la producción comercial de embriones bovinos in vitro. Métodos: Utilizando abordajes de la genética y ecología de poblaciones basados en marcadores microsatélites, evaluamos la diversidad genética entre y dentro de poblaciones de vacas participantes de programas comerciales de producción de embriones in vitro en Brasil. Resultados: La endogamia dentro de las poblaciones varió de cero a 9,1%, mientras que la heterocigosidad entre poblaciones (FST) fue <0,05 en las diferentes interacciones de la población. El AMOVA mostró variación del 1% entre poblaciones, 8% entre individuos y 91% dentro de individuos. El método de reducción de dimensionalidad utilizado indicó una falta de estructura en las poblaciones analizadas, identificando dos grupos principales en las tres poblaciones. Conclusiones: Se evidenció una baja diversidad genética entre las poblaciones de vacas asociadas a programas comerciales de producción de embriones in vitro en Brasil. Se evidenciaron niveles variables de endogamia entre las poblaciones. Abordajes de la genética poblacional, así como de diversidad ecológica pueden ser implementados para estimar de manera más amplia la diversidad genética en poblaciones animales de interés pecuario.

Abstract Background: Current reproductive management of bovine elite populations involves the use of assisted reproductive technologies (ARTs), aiming to obtain the greatest genetic gain. However, inadequate use of ARTs may lead to loss of genetic diversity in the offspring. Objective: To assess the genetic diversity in elite female cattle populations used in commercial in vitro embryo production. Methods: Using genetic and ecological approaches for the study of populations based on microsatellite markers, we assessed the genetic diversity between and within populations of cows used in commercial in vitro embryo production programs in Brazil. Results: Endogamy within populations varied from zero to 9.1%, while heterozygosity between populations (FST) was <0.05 in the different population interactions. AMOVA showed 1% variation between populations, 8% between individuals and 91% within individuals. The dimensionality reduction method utilized indicated a lack of structure in the populations analyzed, identifying two main clusters in the three populations. Conclusions: Low genetic diversity between cow populations associated with commercial programs of in vitro embryo production in Brazil was evidenced. Variable levels of endogamy within the populations were observed. Approaches of population genetics as well as ecological diversity can be implemented to more thoroughly estimate genetic diversity in livestock populations.

Resumo Antecedentes: O atual manejo reprodutivo das populações de elite em bovinos envolve o uso de tecnologias de reprodução assistida (ARTs), visando obter o maior ganho genético. No entanto, o uso inadequado de ARTs pode levar à perda de diversidade genética na prole. Objetivo: Avaliar a diversidade genética em populações de vacas de elite utilizadas na produção comercial de embriões bovinos in vitro. Métodos: Utilizando abordagens da genética e ecologia de populações baseadas em marcadores microssatélites, foi avaliada a diversidade genética entre e dentro das populações de vacas participantes de programas comercias de produção in vitro de embriões. Resultados: A endogamia dentro das populações variou de zero a 9,1%, enquanto a heterozigosidade entre populações (FST) foi <0,05 nas diferentes interações populacionais. AMOVA mostrou variação de 1% entre populações, 8% entre indivíduos e 91% dentro de indivíduos. O método de redução de dimensionalidade utilizado indicou uma falta de estrutura nas populações analisadas, identificando dois clusters principais nas três populações. Conclusões: Baixa diversidade genética entre populações de vacas associadas a programas de produção in vitro de embriões foi evidenciada. Níveis de endogamia variáveis dentro das populações foram observados. Abordagens da genética populacional assim como de diversidade ecológica podem ser implementadas na tentativa de estimar de maneira mais abrangente a diversidade genética em populações animais de interesse pecuário.

ABSTRACT The objective of this study was to evaluate the effect of environment on follicular diameter and repeatability of the size of preovulatory follicles of mares. Temperature, rainfall, and photoperiod were measured, and their effects were evaluated on follicular dynamics. Data were studied by analysis of variance of follicular size and environment traits. During the five years, 7% double ovulations and 159 anovulatory follicles were recorded. Mean preovulatory follicle diameters of left and right ovaries were 39.3±3.8 and 39.2±3.5 mm respectively. There was no effect of evaluation year on follicular diameter. Reproduction season affected the right preovulatory follicle diameter. There was no effect of temperature and rainfall on follicular diameter. Repeatability values of the preovulatory follicular diameter were low. In the subtropical climate studied, temperature and rainfall caused no effect on follicular dynamics, and photoperiod had only a small effect on dominant preovulatory follicular diameter. Repeatability of follicular diameter was low, so this characteristic should be evaluated daily to predict ovulation and the optimal time to inseminate mares.

Resumen Antecedentes: Es importante realizar examen andrológico de sementales para predecir su potencial reproductivo. Objetivo: Evaluar la asociación entre características testiculares, número total de espermatozoides y testosterona con la fertilidad de sementales de raza Mangalarga Marchador. Métodos: Las características medidas fueron: longitud testicular, ancho y altura del testículo. También fue calculado el volumen testicular derecho, izquierdo y total, así como el número total de espermatozoides (TNS), concentración sérica de testosterona y fertilidad (por recuperación embrionaria de las yeguas) de los sementales dentro y fuera de la temporada reproductiva durante un año. Se realizó análisis de varianza para evaluar el efecto de categoría de edad (AC) y estación reproductiva sobre las características. Resultados: La AC no influenció las características testiculares (p>0,05). La estación reproductiva influenció la longitud del testículo izquierdo, la altura del testículo izquierdo, y el ancho y altura del testículo derecho (p<0,05). La AC y la estación reproductiva influenciaron el volumen testicular (p<0,05). No hubo efecto de AC y estación reproductiva en el TNS y testosterona (p>0,05). Se observó una alta correlación entre todas las características testiculares y el volumen testicular (0,53 a 0,75), mediana correlación entre TNS y el volumen testicular (0,32), y una baja correlación entre las medidas testiculares y la testosterona (0,20). La repetitividad de las medidas testiculares fue media a alta (0,22 a 0,78). La tasa de recuperación embrionaria fue de 60% y la correlación con TNS fue 0,44. Conclusión: Para predecir la producción espermática se recomienda evaluar las características testiculares, sin necesidad de medir testosterona. La producción espermática es un buen predictor de la fertilidad de los sementales.

Abstract Background: Assessing breeding soundness is important to predict the potential fertility of stallions. Objective: To investigate the association of testis traits, total number of spermatozoa, and testosterone with fertility of Mangalarga Marchador breed stallions. Methods: The traits measured were testicular length, width and height, right and left testicular volume and total testicular volume. We also evaluated the total number of spermatozoa (TNS), serum testosterone concentration and fertility of stallions (by embryo recovery from donor mares) in the breeding and non-breeding seasons during 1 year. Analysis of variance was performed to verify the effects of age category (AC; young/adult) and reproductive season on the traits. Correlations and repeatability of the traits were also calculated. Results: The AC did not influence testis traits (p>0.05). Reproduction season affected left testicular length, left testicular height, right testicular width and height (p<0.05). The AC and season affected testis volume (p<0.05). There were no effects of AC and season on TNS and testosterone (p>0.05). We observed strong correlations between all testicular measurements and testicular volume (0.53 to 0.75), medium correlation between TNS and testis volume (0.32), and low correlation between testosterone and testis traits (0.20). Repeatability of the characteristics of left and right testis was medium to high (0.22 to 0.78). Embryo recovery rate was 60% and its correlation with TNS was 0.44. Conclusion: Testis size evaluation is recommended over the evaluation of serum testosterone concentration to predict sperm output. Sperm output (TNS) is a good predictor of stallion fertility.

Resumo Antecedentes: Realizar o exame andrológico no garanhão, é importante para predizer seu potencial reprodutivo. Objetivo: Avaliar a associação das características testiculares, número total de espermatozoides, testosterona e fertilidade de garanhões Mangalarga Marchador. Métodos: As características mensuradas foram: comprimento do testículo, largura do testículo e altura do testículo. Também foi calculado o volume testicular, direito, esquerdo e total, assim como calculado o número total de espermatozoides (TNS), concentração sérica de testosterona e fertilidade dos garanhões (pela recuperação embrionária das éguas doadoras) durante e fora da estação reprodutiva durante um ano. Foi feita análise de variância para verificar efeito da categoria de idade (AC) e estação reprodutiva sobre as características. Resultados: A AC não influenciou nas características testiculares (p>0,05). Estação reprodutiva influenciou no comprimento testicular esquerdo, altura testicular esquerda, largura e altura testicular direita (p<0,05).A AC e estação reprodutiva influenciaram no volume testicular (p<0,05). Não houve efeito da AC e estação reprodutiva no TNS e testosterona (p>0,05). Foi observado alta correlação entre todas características testiculares e volume testicular (0,53 a 0,75), media correlação entre TNS e volume testicular (0,32), e baixa correlação entre medidas testiculares e testosterona (0,20). A repetitividade das medidas testiculares foi meia a altas (0,22-0,78). A taxa de recuperação embrionária foi 60% e a correlação com TNS foi de 0,44. Conclusão: É recomendada a avaliação das características testiculares para predizer a produção espermática sem necessidade de mensurar testosterona. A produção espermática é um bom preditor da fertilidade dos garanhões.

ABSTRACT This work aimed to investigate the relationship between echogenicity, testicular biometry, and accessory gland biometry and evaluate the echogenicity pattern of these structures in Santa Ines rams. Fifty-four healthy Santa Ines sheep were classified into three age groups: group 1 - 3 to 5 months (pre-pubertal); group 2 - 7 to 11 months (pubertal); and group 3 - 13 to 28 months (sexually mature). The averages of testicular biometry and bulbourethral gland biometry were different among age groups. The testicular parenchyma was homogeneous with low echogenicity (pre-pubertal group) and medium echogenicity (pubertal and sexually mature groups), suggesting that testicular echogenicity can be a helpful tool to identify the start of puberty. The accessory glands were heterogeneous with low echogenicity in all age groups. Correlations were high between weight, biometry of testis and of bulbourethral gland and echogenicity of the accessory glands, indicating that sexually mature rams with higher body development have larger testicles and larger glands. We recommend the use of testicular biometry as a complementary evaluation of the reproductive efficiency of Santa Ines rams. The average values of echogenicity and the biometry of accessory glands are important parameters to assist the selection of breeding rams.

RESUMO Avaliação do tamanho dos testículos é muito importante na seleção de garanhões, uma vez que é um determinante indireto do seu potencial reprodutivo. O objetivo deste estudo foi avaliar as características de biometria testiculares, calcular o volume testicular e analisar a concentração sérica de testosterona de garanhões. Durante seis meses, foram medidos os testículos de garanhões Pôneis da raça Brasileiro adultos, criados no Norte do Estado do Rio de Janeiro, Brasil. O comprimento a largura e a altura dos testículo (TL, TW e TH) foram mensurados. A partir dessas medidas, calculou-se o volume testicular total (TTV). Os dados foram avaliados por análise de variância e foram calculadas as correlações entre as características. A média geral das características de biometria testicular e volume testicular foram: TL 5,8 ± 0,6 cm; TW 3,8 ± 0,5 cm; TH 4,7 ± 0,4 cm e TTV 111.2 ± 27,7. A média de concentração sérica de testosterona foi de 0,89 ± 0,52 ng/dl. Altas correlações foram observadas entre as características de biometria testicular e volume testicular. Baixas a médias correlações entre as características testiculares com produção espermática e com concentração de testosterona foram observadas. O tamanho testicular pode ser uma importante característica que auxilia na predição do potencial reprodutivo do garanhão pôneis da raça Brasileira. Sugere-se que não há variações na concentração sérica de testosterona nos pôneis da raça Brasileira que poderia afetar em sua fertilidade.

SUMMARY Evaluation of the testis size is very important in stallions’ selection, since it is an indirect determinant of their reproductive potential. The aim of this study was to evaluate the biometric testicular traits, calculate the volume testicular and analyze the serum testosterone concentration of the stallion. During six months were measured the tests of adults Brazilian Ponies stallions from northern of Rio de Janeiro State, Brazil. The length, the width and the height of the testicles (TL, TW and TH) were measured. From these measurements, the total testicular volume (TTV) was calculated. The serum testosterone concentration was also evaluated. The data were studied by analysis of variance and were calculated the correlations among the traits. The average of the testis biometry were TL 5.8 ± 0.6 cm; TW 3.8 ± 0.5 cm; TH 4.7 ± 0.4 cm and 111.2 ± 27.7 for TTV. Mean of serum testosterone concentration was 0.89 ± 0.52 ng/dl. High correlations between biometry testicular traits with testicular volume were observed and low to moderate correlations were observed for testicular traits, testosterone and sperm output. The testis size could be an important trait that assists to the prediction of stallion's reproductive potential of the Brazilian ponies stallions. It is suggested that there would be no fluctuation in serum testosterone concentration in Brazilian ponies stallions that coult afect on its fertility.