TY - JOUR
T1 -
Sensitivity of sheep to exogenous prostaglandin F
2α
early in the estrous cycle
AU - Pope, W. F.
AU - Cárdenas, H.
PY - 2004/10/1
Y1 - 2004/10/1
N2 -
One hundred ewes were monitored twice-a-day for estrus and only those ewes displaying an estrous cycle of 16.5-18.0 days in length were utilized in the experiment. Ewes were subsequently treated with a single injection of 5 or 10 mg of prostaglandin F
2α
(PGF
2α
) on days 3.0, 3.5, 4.0, 4.5 or 5.0 (n=10 ewes per day) of the estrous cycle (day 0.0=the a.m. or p.m. of first detected estrus) to determine their sensitivity to induction of estrus with prostaglandin F
2α
. Ewes that were detected in estrus within 24-72 h after treatment with PGF
2α
were considered sensitive to PGF
2α
treatment. This definition of sensitivity to PGF was inclusive as all ewes either responded within 24-72 h after PGF
2α
treatment or they came into estrus at the expected time based on their previous, untreated, estrous cycle. Results indicated that a significant (P<0.05) proportion of ewes became sensitive to the induction of estrus with PGF
2α
between days 3.5 and 4.0, as 10 and 50% of the ewes, respectively, responded to treatment. PGF
2α
treatment on days 4.5 and 5.0 caused a non-significant increase in responsiveness as 70 and 75% of the ewes, respectively, came into estrus within 1-3 days. The 10 mg dose, being more effective than the 5 mg dose, shifted the response curve by roughly 20 percentage points beginning on day 3.5 and continued through the later exposure times. In conclusion, the CL early in the estrous cycle of ewes was variable in its responsive to a single exposure to PGF
2α
and some of this variability was attributed to physiological events occurring between days 3.5 and 4.0.
AB -
One hundred ewes were monitored twice-a-day for estrus and only those ewes displaying an estrous cycle of 16.5-18.0 days in length were utilized in the experiment. Ewes were subsequently treated with a single injection of 5 or 10 mg of prostaglandin F
2α
(PGF
2α
) on days 3.0, 3.5, 4.0, 4.5 or 5.0 (n=10 ewes per day) of the estrous cycle (day 0.0=the a.m. or p.m. of first detected estrus) to determine their sensitivity to induction of estrus with prostaglandin F
2α
. Ewes that were detected in estrus within 24-72 h after treatment with PGF
2α
were considered sensitive to PGF
2α
treatment. This definition of sensitivity to PGF was inclusive as all ewes either responded within 24-72 h after PGF
2α
treatment or they came into estrus at the expected time based on their previous, untreated, estrous cycle. Results indicated that a significant (P<0.05) proportion of ewes became sensitive to the induction of estrus with PGF
2α
between days 3.5 and 4.0, as 10 and 50% of the ewes, respectively, responded to treatment. PGF
2α
treatment on days 4.5 and 5.0 caused a non-significant increase in responsiveness as 70 and 75% of the ewes, respectively, came into estrus within 1-3 days. The 10 mg dose, being more effective than the 5 mg dose, shifted the response curve by roughly 20 percentage points beginning on day 3.5 and continued through the later exposure times. In conclusion, the CL early in the estrous cycle of ewes was variable in its responsive to a single exposure to PGF
2α
and some of this variability was attributed to physiological events occurring between days 3.5 and 4.0.
KW - Estrous cycle
KW - Estrus
KW - Prostaglandin
KW - Sheep
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U2 - 10.1016/j.smallrumres.2004.01.004
DO - 10.1016/j.smallrumres.2004.01.004
M3 - Article
AN - SCOPUS:4344599586
VL - 55
SP - 245
EP - 248
JO - Small Ruminant Research
JF - Small Ruminant Research
SN - 0921-4488
IS - 1-3
ER -