Plasma steroid dynamics in late- and near-term naturally and artificially conceived bovine pregnancies as elucidated by multihormone high-resolution LC-MS/MS.

The plasma levels of corticosteroids and sex steroids during pregnancy are key indicators of mammalian placental function and the onset of parturition. Steroid hormones are believed to be disturbed in pregnancies produced using assisted reproductive technologies (ARTs) due to placental dysfunction and the frequently observed lack of parturition signals. To elucidate the plasma steroid dynamics, a liquid chromatography-tandem mass spectrometry method was developed and used to determine the levels of corticosteroids (corticosterone, 11-deoxycortisol, and cortisol) and their direct precursors (progesterone and 17α-OH-progesterone) as well as sex steroids (androstenedione, estrone, estrone sulfate, testosterone, and 17ß-estradiol) in bovine plasma. The levels of these 10 steroids in recipient cows carrying naturally conceived (control), in vitro fertilized (IVF), or cloned (somatic cell nuclear transfer) conceptuses were compared during late-term pregnancy (30 days before parturition), during near-term pregnancy (1 day before parturition), and on the day of parturition (day 0). Significant differences were observed among the corticosteroid levels: higher levels of corticosterone, 11-deoxycortisol, and cortisol were detected in cloned pregnancies at day 30; lower levels of corticosterone were observed in ART-derived pregnancies at days 1 and 0; and estrone and estradiol levels were higher in IVF pregnancies throughout the final development. These results suggested an upregulation of the P450C11 and P450C21 enzymes 30 days before parturition in somatic cell nuclear transfer pregnancies and an overactivation of the aromatase enzyme in IVF pregnancies. Taken together, the monitoring of multiple steroid hormones revealed that the pregnancies obtained using ART exhibited plasma steroid concentration dynamics compatible with the dysregulation of steroidogenic tissues.

Higher feeding diets effects on age and liveweight gain at puberty in crossbred Nelore × Hereford heifers.

This study was conducted to determine the age and liveweight at puberty of 120 crossbred beef heifers submitted to four diets to achieve predetermined weight gains (kg/day): 0.5 (G500; n = 32), 0.75 (G750; n = 32), 1.0 (G1000; n = 29), and 1.25 (G1250; n = 27). Animals were classified depending on their level of crossing between Nelore (N) and Hereford (H): 25%N-75%H, 37.5%N-63.5%H, 43.7%N-56.7%H, 50%N-50%H, and 75%N-25%H. Reproductive evaluation was performed at the beginning and at the end of the experimental period by ultrasonography and hormone analysis. The average age and liveweight at puberty were 388.0 ± 1.9 days and 331.4 ± 1.3 kg, respectively. Animals from the 25%N-75%H group reached puberty earlier than heifers from other genetic groups supplemented with G1250 diet (P < 0.05). Heifers with higher degree of Nelore (75%N-25%H) fed with G1000 diet showed estrus 42 days prior to mating, but only 57% reached puberty at mating (P < 0.05). Heifers with follicles of higher diameter reached puberty (P < 0.05) earlier. Higher average daily weight gain showed a positive effect on follicular diameter and IGF-I level at puberty (P < 0.01). Concentrations of GH were lower in heifers fed G1250 compared to G1000 diet (P < 0.05). There was a significant interaction between nutritional level and insulin levels at puberty (P < 0.01). We demonstrated the relationship between IGF-I and average daily gain on the onset of puberty in heifers. In conclusion, heifers submitted to the higher feeding level showed a higher follicular diameter and were younger at puberty.

Condição sociossexual de uma população de pôneis da raça Brasileira / Social-sexual condition of the Brazilian Pony Breed population

A formação dos haréns em pôneis envolve variáveis como as concentrações plasmáticas de testosterona, a idade e a dominância entre garanhões. Os objetivos deste estudo foram verificar a estabilidade e a repetibilidade da composição dos haréns e as relações entre as concentrações plasmáticas de testosterona e a condição sociossexual dos reprodutores. A estabilidade dos haréns dependeu do status reprodutivo das fêmeas. A presença de éguas gestantes no harém levou a uma maior estabilidade, enquanto que as em estro, ao procurarem outros garanhões para serem cobertas, provocaram instabilidade. A condição de dominante do garanhão foi importante para a manutenção do número de éguas no seu harém. Todos os garanhões tiveram as suas concentrações plasmáticas médias de testosterona aumentadas, em média, 77,6 por cento, quando foram expostos às éguas e quando formaram haréns (85,6 por cento), enquanto que os do grupo de solteiros tiveram as concentrações mais baixas. Portanto, fatores envolvidos na formação e estabilidade dos haréns nas populações selvagens parecem também exercer influência nas domesticadas e, consequentemente, podem interferir no desempenho destes animais durante a estação reprodutiva.

The formation of harems in ponies involves factors as testosterone level of stallion, age and dominance. The objectives were to verify the stability and repeatability of the composition of harems and the relationships between plasmatic levels of testosterone and the social-sexual condition of the stallions. The stability of harems depended of reproductive status of females and dominance of stallion. All the stallions had their mean testosterone plasmatic levels increased, in average, 77, 6 percent, when were exposed to the mares, and when they formed harems (average of 85, 6 percent), while the stallions of bachelor group had lower levels.

Condição sociossexual de uma população de pôneis da raça Brasileira / Social-sexual condition of the Brazilian Pony Breed population

A formação dos haréns em pôneis envolve variáveis como as concentrações plasmáticas de testosterona, a idade e a dominância entre garanhões. Os objetivos deste estudo foram verificar a estabilidade e a repetibilidade da composição dos haréns e as relações entre as concentrações plasmáticas de testosterona e a condição sociossexual dos reprodutores. A estabilidade dos haréns dependeu do status reprodutivo das fêmeas. A presença de éguas gestantes no harém levou a uma maior estabilidade, enquanto que as em estro, ao procurarem outros garanhões para serem cobertas, provocaram instabilidade. A condição de dominante do garanhão foi importante para a manutenção do número de éguas no seu harém. Todos os garanhões tiveram as suas concentrações plasmáticas médias de testosterona aumentadas, em média, 77,6 por cento, quando foram expostos às éguas e quando formaram haréns (85,6 por cento), enquanto que os do grupo de solteiros tiveram as concentrações mais baixas. Portanto, fatores envolvidos na formação e estabilidade dos haréns nas populações selvagens parecem também exercer influência nas domesticadas e, consequentemente, podem interferir no desempenho destes animais durante a estação reprodutiva.(AU)

The formation of harems in ponies involves factors as testosterone level of stallion, age and dominance. The objectives were to verify the stability and repeatability of the composition of harems and the relationships between plasmatic levels of testosterone and the social-sexual condition of the stallions. The stability of harems depended of reproductive status of females and dominance of stallion. All the stallions had their mean testosterone plasmatic levels increased, in average, 77, 6 percent, when were exposed to the mares, and when they formed harems (average of 85, 6 percent), while the stallions of bachelor group had lower levels.(AU)

Temperamento e comportamento materno-filial de ovinos das raças Corriedale e Ideal e sua relação com a sobrevivência dos cordeiros / Temperament and maternal behavior of Corriedale and Pollwarth sheep and its relation with lamb's survival

O experimento foi conduzido na Estação Experimental da Embrapa, Bagé, Rio Grande do Sul, entre março de 2005 e fevereiro de 2006. O objetivo foi avaliar o comportamento materno-filial e o temperamento de ovelhas e cordeiros e relacioná-los com a sobrevivência dos cordeiros. Foram utilizadas 47 ovelhas da raça Corriedale, com peso médio de 52,1kg, e 45 ovelhas da raça Ideal, com peso médio de 49,5kg, em um delineamento inteiramente casualizado. O temperamento foi avaliado por meio dos testes: escore de comportamento materno (ECM), tempo de fuga, tipo de marcha e distância de fuga. As ovelhas da raça Corriedale apresentaram maiores valores no teste tipo de marcha que as ovelhas da raça Ideal. Os cordeiros da raça Corriedale eram os mais pesados e tinham maior índice de sobrevivência, quando comparados com os da raça Ideal. A raça não afetou o escore de comportamento materno. Ovelhas reativas (ECM=1), que fogem e não retornam aos seus cordeiros, se isolaram menos do rebanho antes do parto, protegeram menos suas crias, desmamaram-nas mais cedo e tiveram menor peso em relação às não-reativas. A reatividade das ovelhas prejudicou o cuidado materno com os cordeiros e essa característica deve ser considerada pelo setor produtivo.

The trial was conducted at the Experimental Station of Embrapa, Bagé, RS, from March 2005 to February 2006, and aimed to evaluate the maternal behavior and temperament of ewes and their lambs and related them with lamb's survival. Forty-seven Corriedale ewes with mean body weight of 52.1kg and 45 Pollwarth ewes with mean body weight of 49.5kg were used, according to a completely randomized design. Temperament was evaluated through maternal behaviour score (MBS), flight time test (score and quantitative) and flight distance. Corriedale ewes presented larger values for flight time score than Pollwarth ewes. Corriedale lambs were heavier and a greater number survived than Pollwarth lambs. Sheep breed did not affect maternal score. Ewes considered reactive (MBS=1, those who run away and did not come back to stay with their lamb) seek less isolation from the herd at parturition, protected less their lambs, weaned them earlier and lighter than less reactive ewes. Reactivity decreased maternal care of ewes with its lambs, and this characteristic might be considered by productive systems.