Letter | Published:

Prolactin levels and duration of postpartum anoestrus in lactating ewes

Naturevolume 257pages6364 (1975) | Download Citation



THE length of the postpartum anoestrous period in sheep is related to the degree of mammary stimulation. If the ewe is milked by hand twice a day or ‘dried off’ immediately after parturition, the first oestrus occurs 30–40 d postpartum in the ‘Préalpes du Sud’ breed; if the ewe is nursing her lamb(s)—suckling 10–12 times per day—postpartum anoestrus lasts for 60–80 d (ref. 1). A similar phenomenon has been described in women; menses reappear within 10 weeks postpartum in 80% of women who are not breast feeding, but in only 10% of those who are2. In both species suckling is accompanied by large discharges of oxytocin and prolactin; this reflex secretion of prolactin decreases as lactation progresses, and is almost nonexistent by the time of return of cyclical ovarian activity.

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  1. Laboratoire de Physiologie de la Lactation, INRA, 78350, Jouy-en-Josas, France

    • G. KANN
    •  & J. MARTINET


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