SciELO - Scientific Electronic Library Online

 
vol.58 número5Características andrológicas de touros da raça GirCaracterísticas do sêmen e maturidade sexual de touros jovens da raça Tabapuã (Bos taurus indicus) em diferentes manejos alimentares índice de autoresíndice de assuntospesquisa de artigos
Home Pagelista alfabética de periódicos  

Arquivo Brasileiro de Medicina Veterinária e Zootecnia

versão On-line ISSN 1678-4162

Resumo

LEW, B.J.; MEIDAN, R.  e  WOLFENSON, D.. Hormone concentration and follicular development in dairy cows under seasonal and acute hyperthermia. Arq. Bras. Med. Vet. Zootec. [online]. 2006, vol.58, n.5, pp. 816-822. ISSN 1678-4162.  http://dx.doi.org/10.1590/S0102-09352006000500017.

The present study evaluated the seasonal and acute heat stress on follicular development and steroid and inhibin concentrations in follicular fluid, in bovine dominant follicle. Cows were distributed into four treatments: summer (n=5), autumn (n=5), animals heat stressed during the winter (n=5) and winter (n=9). On day 7 of the estrous cycle, animals were slaughtered and parameters related to follicle development were evaluated. The follicular fluid (FF) was aspirated and stored for further hormonal analysis. During the summer, the number of viable granulosa cells was 40% lower than during the winter, and there was a 45% decrease in this parameter during the autumn (P<0.05). In the winter, estradiol concentration was 62% higher than during the autumn (P<0.05) and 42% higher than during the summer (P<0.06). There was an increase in androstenedione concentration in summer group, when compared to winter (P<0.08) and autumn (P<0.05) groups. Inhibin concentration was higher in winter groups than summer and winter heat stressed groups (P<0.05). Seasonal and acute heat stress altered developmental parameters in dominant follicle and hormonal concentration in follicular fluid, those effects can partially explain the decrease in conception rates during summer.

Palavras-chave : follicle; heat stress; steroids; inhibin; reproduction.

        · resumo em Português     · texto em Português     · Português ( pdf epdf )

 

Creative Commons License Todo o conteúdo deste periódico, exceto onde está identificado, está licenciado sob uma Licença Creative Commons