Seasonal pattern of plasma progesterone, prolactine and melatonine concentrations in ewes kept at lower latitudes / Perfis sazonais das concentrações plasmáticas de progesterona, prolactina e melatonina de ovelhas criadas em baixas latitudes

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

This study evaluated the ovulatory activity throughout the year, plasma melatonin and prolactin concentrations on 24 hours during solstices and equinoces on wool (Romney Marsh - 10) and hair (Santa Inês - 10) ewes kept under natural photoperiod and lower latitudes in the southern hemisphere. To monitor the ovulatory activity, blood samples were collected weekly from the jugular vein throughout the year to determine the plasma progesterone concentrations. To determine the plasma melatonin and prolactin concentrations blood samples were collected each two hours during 24 hours on the solstices and equinoces. Santa Inês and Romney Marsh females showed different ovulatory activity. Wool ewes showed a strong seasonality, and hair ewes were in ovulatory activity all the year. The circadian cycle of plasma melatonin concentrations from Romney Marsh and Santa Inês females showed the same seasonal pattern, and did not showed circannual pattern. The duration of nocturnal secretion plasma melatonin was the same of scotoperiod duration on each season of the year. The plasma prolactin profile from Romney Marsh ewes were higher than Santa Inês ewes in all seasons, but the seasonal pattern was identic. Plasma concentrations were higher in spring and summer than autumm and winter.

ASSUNTO(S)

ovulatory activity santa inês romney marsh natural photoperiod fotoperíodo natural atividade ovulatória santa inês romney marsh

ACESSO AO ARTIGO

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