[Suppression of cycling activity in sheep using parenteral progestagen treatment].
The objective of this study was to evaluate the effect of two synthetic progestagen preparations Chlormadinone acetate (CAP, Chronosyn, Veterinaria AG Zürich) and Medroxyprogesterone acetate (MPA, Nadigest, G Streuli & Co. Uznach) on cycling activity and fertility in sheep. A flock of 28 non pregnant white alpine sheep was randomly divided into three groups, A (n = 10), B (n = 9) and C (n = 9). During a period of 4 weeks the cycling activity was confirmed by blood progesterone analysis. Thereafter, the animals of group A were treated with 50 mg CAP, those of group B with 140 mg MPA and those of group C with physiological saline solution. All injections were given intramuscularly. Suppression of endogenous progesterone secretion lasted from 28 to 49 days (mean = 39 days) in group A and from 42 to 70 days (mean = 50 days) in group B. The synchronization effect of both preparations was unsatisfactory as the occurrence of first estrus was distributed over a period of 3 weeks in group A and 4 weeks in group B. These findings could also be confirmed by the lambing period which lasted 52 days in group A and 36 days in group B. Control animals lambed within 9 days due to the synchronizing effect of the ram. The first fertile estrus was observed 36 days (group A) and 45 days (group B) after the treatment. In group A all 10 animals and in groups B and C 8 of 9 ewes each became pregnant. Parenteral progestagen application with CAP and MPA is a simple, safe and reversible method of estrus suppression in the sheep. The minimal suppressive duration of 4 (CAP) and 5 weeks (MPA) is not sufficient when a period of 3 months (alpine pasture period) is desired.
Janett
F
F
Klinik für Fortpflanzungsmedizin, Universität Zürich. fjanett@vetclinics.unizh.ch
Camponovo
L
L
Lanker
U
U
Hässig
M
M
Thun
R
R
D000818:Animals; D002715:Chlormadinone Acetate / Q000494:pharmacology*; D003271:Contraceptive Agents, Female / Q000494:pharmacology*; D004971:Estrus / Q000187:drug effects*; D005260:Female; D005298:Fertility / Q000187:drug effects; D017258:Medroxyprogesterone Acetate / Q000494:pharmacology*; D011247:Pregnancy; D011374:Progesterone / Q000097:blood; D011897:Random Allocation; D012756:Sheep / Q000502:physiology*; D013997:Time Factors
D003271:Contraceptive Agents, Female; D002715:Chlormadinone Acetate; D011374:Progesterone; D017258:Medroxyprogesterone Acetate