Efeito da superovulação sobre o desempenho de bovinos doadores de embrião importados de clima temperado para clima tropical nos dois primeiros anos de adaptação

Avaliou-se o desempenho de fêmeas bovinas doadoras de embrião nos primeiros dois anos de trabalho em um centro do programa multiple ovulation and embryo transfer (MOET). Utilizaram-se novilhas prenhes de recente importação de clima moderado para o Nordeste Brasileiro. Compararam-se os resultados de superovulação em 1996, primeiro ano de adaptação dos animais, e 1997 com AUSA-Superov (FSH) e Folligon (eCG). O número de CL contados no ovário foi 3,3 (FSH) e 4,2 (eCG) em 1996 e 8,2 (FSH) e 9,6 (eCG) em 1997, o de óvulos e embriões degenerados coletados de 2,8 (FSH) e 3,8 (eCG) em 1996 e 6,5 (FSH) e 7,4 (eCG) em 1997, o de embriões de boa qualidade de 1,9 (FSH) e 2,3 (eCG) em 1996 e 5,5 (FSH) e 4,0 (eCG) em 1997. A eficiência da coleta foi de 40% (FSH) e 35% (eCG) em 1996 e 85% (FSH) e 83% (eCG) em 1997. Todos os valores citados para 1996 e 1997 foram significativamente diferentes (P<0,05). Em 1997 foram utilizados dois produtos novos, Pluset e Folltropin-V, ambos à base de pFSH. Com Pluset o número de óvulos e embriões degenerados lavados foi de 11,7 unidades/doadora e o número de embriões de boa qualidade foi de 5,1 unidades/lavagem. Com Folltropin-V, o número foi de 4,5 unidades/lavagem e o de embriões viáveis de 1,9 unidades/doadora. Melhores resultados foram obtidos com Pluset (P<0,05)

Effect of the El Nińo phenomenon on the ovarian responsiveness and embryo production of donor cows

The effects of different Temperature Humidity Index (THI) values in cold, hot and El Niño (EN) climates on superovulation and embryo production were analysed on Holstein Friesian donor cows. There were significant differences in the THI among the three climates. The average temperature in the EN period was 6°C higher than in the summer period of the previous 30 years. The number of corpora lutea (CL) and embryos were log- and back-transformed, Kolmogorov-Smirnoff test was used for normality and Lilliefors test was applied for significance. In the cold season THI was 70.74 ± 1.35 and the average number of CL was 9.84 ± 4.37. In the hot season the THI was 73.99 ± 0.72 and the average number of CL was 9.70 ± 4.49. When the THI, in the EN period, increased up to 79.74 ± 4.01, the superovulation response was significantly (P < 0.01) reduced (average number of CL = 5.22 ± 2.53). The embryo production result showed a similar tendency. In the hot period the average number of embryos obtained was 5.87 ± 2.98. However, in the EN period it decreased to 4.21 ± 2.05. Higher temperature reduced embryo quality. The proportion of live embryos (%) was 59.2 ± 37.4 in the cold and 38.2 ± 38.5 in the EN periods of the year (P < 0.01). However, ovarian sensitiveness showed adaptation to summer environment while the heat stress, which was more severe in the EN period, negatively affected the superovulation response and embryo production

Progesterone profiles and oestrous cycle changes following superovulatory treatment of Holstein-Friesian dairy cows in a tropical environment

Changes of progesterone (P4) profiles and oestrous cycle were investigated up to 70 days in 20 superovulated Holstein-Friesian cows in a dry tropical environment (Brazil). Superovulated cows showed no significant differences in relation to P4 level at the time of embryo recovery (39.0 ± 27.1 nmol/L, P = 0.536), first and second (12.0 ± 6.0 and 10.7 ± 2.2 nmol/L, P = 0.543) cycle. There was a close correlation between serum P4 concentration and the number of corpora lutea (CL; 13.3 ± 9.5) at the recovery (P < 0.0001). After the embryo collection, cows returned to cycle in different ways: (i) group of donors returning to cycle after 2.2 ± 0.8 days, (ii) group with a delay of 11.0 ± 1.9 days; and (iii) animals having a long (28.8 ± 2.2 days) acyclic period, which is significant (P < 0.001). The remaining animals (30%) showed cystic ovarian malformations. P4 level at the time of embryo recovery does not influence the oestrous cycle changes. The results suggest that Holstein-Friesian donor cows may suffer from cystic ovarian degeneration and may have a long acyclic period after superovulatory treatment in a tropical climate