Objetivou-se com este estudo avaliar o efeito do fornecimento de Acetato de Melengestrol (MGA®Premix) após IATF (inseminação artificial em tempo fixo), sobre a taxa de concepção em vacas paridas da raça Nelore. Experimento I, avaliou-se o efeito do fornecimento de 2,28g de MGA/ vaca/ dia, do dia 13 (D13) ao dia 18 (D18) após a IATF. As vacas foram divididas em dois grupos, sendo o Grupo I (n=83, controle) que foi realizado apenas IATF e Grupo II (n=104, tratado) que foi fornecido o MGA após a IATF. Experimento II, avaliou-se o efeito do fornecimento de 2,28g de MGA/ vaca/ dia, do dia cinco (D5) ao dia 10 (D10) após a IATF. As vacas foram divididas em dois grupos, sendo o Grupo I (n=94, controle) que foi realizado apenas IATF e Grupo II (n=100, tratado) que foi fornecido o MGA após a IATF. O diagnóstico de gestação foi realizado 45 dias após a IATF em ambos os experimentos. As taxas de concepção foram comparadas pelo teste de Qui-quadrado. No Experimento I, as taxas de concepção foram de 42,16% para o grupo controle e 50,0% para o grupo tratado. No Experimento II, a taxa de concepção do grupo controle (47,87%) foi significativamente maior do que o grupo tratado (28,0%). Conclui-se que o fornecimento de MGA®Premix, administrado do D13 ao D18 após a IATF não afetou a taxa concepção. Entretanto, quando fornecido do D5 ao D10, reduziu a taxa de concepção em vacas Nelore paridas.

The objective of the work was evaluate the effect of the feedingwith different rude protein levels under the sexual maturity and quality of semen of boars. The swines were fed with diets contend 12%, 16% and 20% of rude protein. Were used 11 animals of commercial ancestries. For evaluation of the sexual behavior and adaptation of the piglets, from 151 days of age the animals were placed in contact with the dummy for semen harvest one time per week, per 15 minutes. Evaluated concentration (millions/mL), total motility (TM), progressive motility (MP), vigor (v) and morphologic alterations (AM). The animals fed with diets contend 16% of PB presented better resulted of male behavior. The average results of the parameters: jumps on the dummy, number of mount, exposition of penis, TM, MP, V and spermatic concentration, not differed between the treatments 5% from significance. The values of AM found in this study differed statistical between itself. The parameter sexual maturity presented significant difference between the swines that received diets contend 20% and the animals that received diets with 12% and 16% from PB. The castrated male swines of T16% not presented male behavior better. Not have difference in the quality of the semen of boars feeding with different rude protein levels (12%, 16% and 20%) since weans until reaching the sexual maturity. The animals that received diets with 20% from PB reached the sexual maturity more precociously.

The present study evaluated the effect of administering buserelin acetate (GnRH) at the time of fixedtime artificial insemination (FTAI), along with the effect of oral administration of melengestrol acetate (MGA) after FTAI on conception rates in non-suckling Nelore cattle. In Experiment I, the effect of GnRH application at the time of FTAI was evaluated, as was administration of MGA from the 13 th through the 18 th day following FTAI (D24 to D29 after the initiation of the FTAI protocol). Experiment I was performed in 215 non-suckling cattle of the Nelore breed, divided into four experimental groups: Control group: 56 cows subjected to FTAI without GnRH injection; GnRH group: 51 cows subjected to GnRH at the time of FTAI; MGA Group: 57 cows subjected to FTAI without the application of GnRH with mineral supplementation and the addition of 2.28 g of MGA ® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol; MGA and GnRH group: 51 cows subjected to GnRH injection at the time of FTAI, with mineral supplementation and the addition of 2.28 g of MGA ® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol. In Experiment II, the effect of providing MGA five to ten days after FTAI was evaluated in 196 non-suckling pluriparous Nelore cows, divided into two groups: Control group: 104 cows subjected to FTAI, not supplemented with MGA; treated group: 92 cows supplemented with the addition of 2.28 g of MGA ® Premix per cow per day from D15 to D20 after the initiation of the FTAI protocol. Diagnosis of gestation was carried out 45 days after FTAI. Both experiments were conducted using a completely randomised design and analysed via the SAS MIXED procedure. In Experiment I, the control group displayed a lower conception rate (32.1%) compared with the groups administered GnRH, MGA, and both MGA and GnRH, which were respectively provided with MGA after FTAI (45.6%), GnRH at the time of FTAI (50.9%), and the combination of the two treatments (50.9%) (P<0.05). In Experiment II, the control group displayed a higher conception rate (40.38%) compared with the group receiving MGA post-FTAI (18.48%) (P<0.05). It was concluded that the injection of buserelin acetate (GnRH) at the time of FTAI and the oral administration of MGA ® Premix from the 13 th to the 18 th day after FTAI increased the conception rates in non-suckling Nelore cattle. However, when MGA ® Premix was administered orally from the fifth to tenth day post-FTAI, conception rates in non-suckling Nelore cattle were reduced.

A qualidade das amostras de sêmen é fundamental para o sucesso dos programas de inseminação artificial em bovinos. Torna-se imprescindível a manutenção das características dos espermatozoides por meio de adequado processo de criopreservação. No entanto, os processos de criopreservação resultam na formação contínua e excessiva de espécies reativas de oxigênio (EROS), que são prejudiciais aos espermatozoides, pois induz a apoptose com consequente redução da qualidade espermática. Dessa forma, têm sido acrescidos aos crioprotetores substâncias antioxidantes como a glutationa e a melatonina, as quais tem como intuito minimizar os efeitos deletérios causados pelas EROS aos espermatozoides, resultando em melhor qualidade espermática, com consequente aumento das taxas de fertilização in vitro.  Diante disso, a presente revisão tem por objetivo analisar os efeitos da adição dos antioxidantes glutationa e melatonina em diferentes meios de criopreservação e a produção in vitro de embriões bovinos.

<p>The present study evaluated the effect of administering buserelin acetate (GnRH) at the time of fixed-time artificial insemination (FTAI), along with the effect of oral administration of melengestrol acetate (MGA) after FTAI on conception rates in non-suckling Nelore cattle. In Experiment I, the effect of GnRH application at the time of FTAI was evaluated, as was administration of MGA from the 13th through the 18th day following FTAI (D24 to D29 after the initiation of the FTAI protocol). Experiment I was performed in 215 non-suckling cattle of the Nelore breed, divided into four experimental groups: Control group: 56 cows subjected to FTAI without GnRH injection; GnRH group: 51 cows subjected to GnRH at the time of FTAI; MGA Group: 57 cows subjected to FTAI without the application of GnRH with mineral supplementation and the addition of 2.28 g of MGA® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol; MGA and GnRH group: 51 cows subjected to GnRH injection at the time of FTAI, with mineral supplementation and the addition of 2.28 g of MGA® Premix per cow per day from D24 to D29 after the initiation of the FTAI protocol. In Experiment II, the effect of providing MGA five to ten days after FTAI was evaluated in 196 non-suckling pluriparous Nelore cows, divided into two groups: Control group: 104 cows subjected to FTAI, not supplemented with MGA; treated group: 92 cows supplemented with the addition of 2.28 g of MGA® Premix per cow per day from D15 to D20 after the initiation of the FTAI protocol. Diagnosis of gestation was carried out 45 days after FTAI. Both experiments were conducted using a completely randomised design and analysed via the SAS MIXED procedure. In Experiment I, the control group displayed a lower conception rate (32.1%) compared with the groups administered GnRH, MGA, and both MGA and GnRH, which were respectively provided with MGA after FTAI (45.6%), GnRH at the time of FTAI (50.9%), and the combination of the two treatments (50.9%) (P&lt;0.05). In Experiment II, the control group displayed a higher conception rate (40.38%) compared with the group receiving MGA post-FTAI (18.48%) (P&lt;0.05). It was concluded that the injection of buserelin acetate (GnRH) at the time of FTAI and the oral administration of MGA® Premix from the 13th to the 18th day after FTAI increased the conception rates in non-suckling Nelore cattle. However, when MGA® Premix was administered orally from the fifth to tenth day post-FTAI, conception rates in non-suckling Nelore cattle were reduced.</p>