The effect of clenbuterol on time of lambing and neonatal death loss.
Two experiments were conducted to test the ability of clenbuterol, a beta-sympathomimetic agonist, to delay lambing. Ewes in all experiments were induced to lamb with 2.5 mg of flumethasone given intramuscularly on Day 141, 142 or 143 of gestation. Beginning on the day of flumethasone administration and continuing daily until lambing, ewes in Experment 1 were given injections intramuscularly (i.m.) with either 1) vehicle solution at 2200 h, 2) 240 ug of clenbuterol at 2200 h or 3) 240 ug of clenbuterol at 1600 and at 2200 h. There was a greater proportion of ewes lambing between 0800 h and 1600 h (P<0.01) and more stillbirths (P=0.05) in the groups which received clenbuterol than in the vehicle control group. Experiment 2 was conducted to determine if a lower dosage of clenbuterol, given as a single injection 37 h after flumethasone, would delay lambing without increasing the proportion of stillbirths. Ewes received either the vehicle solution, or 36 or 146 ug of clenbuterol. Lambing was delayed in the group which received 146 ug but not 36 ug of clenbuterol. There were no adverse effects of treatment on lamb survival in Experiment 2.
Kiesling
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Cooperative Research, Animal Sciences Program, Lincoln University Jefferson City, MO 65101 USA.
Meredith
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Warren
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