Resumption of oestrous behaviour and cyclic ovarian activity in suckling and non-suckling ewes.
In Préalpes de Sud ewes after an autumn lambing, the mean post-partum interval to first LH surge was 10 +/- 1 days and 17 +/- 1 days for non-suckling and suckling ewes, respectively. Post-partum interval to first luteal phase, estimated from plasma progesterone concentrations, was similar in non-suckling and suckling ewes (27 +/- 1 days and 28 +/- 5 days, respectively). Interval to first oestrus was shorter in non-suckling (22 +/- 2 days) than in suckling ewes (35 +/- 2 days) but these first oestrous periods were followed by short luteal phases in 60% (12/20) of non-suckling ewes and in only 7% (2/29) of suckling ewes. Finally, suckling slightly postponed the resumption of the first oestrus followed by a normal oestrous cycle (37 +/- 1 days versus 31 +/- 2 days) because progesterone, essential for oestrus expression, was secreted mainly during normal luteal phases in 70% (21/30) of suckling ewes and during short cycles in 95% (21/22) of non-suckling ewes. Therefore, the primary consequence of suckling is to regulate the conditions of resumption of cyclic ovarian activity after parturition.
Schirar
A
A
Laboratoire de Neurobiologie de la Reproduction, INRA, Jouy-en-Josas, France.
Cognie
Y
Y
Louault
F
F
Poulin
N
N
Levasseur
M C
MC
Martinet
J
J
D000818:Animals; D003338:Corpus Luteum / Q000502:physiology; D004971:Estrus / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000502:physiology*; D007986:Luteinizing Hormone / Q000097:blood; D010053:Ovary / Q000502:physiology*; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D011374:Progesterone; D007986:Luteinizing Hormone