Accelerated lambing using exogenous progesterone and the ram effect.
An experiment was conducted to determine whether controlled internal drug release devices-type G (CIDR-G) could be used in conjunction with the ram effect to advance the breeding season and lambing and thereafter could be reapplied to stimulate breeding of ewes to produce a second lambing in late summer. Finn crossbred and Columbia ewes were treated with CIDR-G from July 6 to 18. Rams, which had been isolated from ewes, were joined with the flock upon CIDR-G removal. All 59 CIDR-G-treated ewes exhibited estrus, and 55 lambed from breeding within a 30-d period after CIDR-G withdrawal. Eighteen of 19 contemporary control ewes (no CIDR-G) were bred, and 16 lambed. Ewes that had lambed from the CIDR-G and control groups were retreated as before, with CIDR_G inserted March 1 and withdrawn March 13, concomitant with sudden exposure to rams. Of 55 CIDR-G-treated sheep, 53 were bred and 45 lambed. All 16 control ewes were bred and lambed. A second experiment was conducted to determine whether treatment with CIDR-G and the ram effect was effective in mid-spring. The CIDR-G were applied for 12 d and removed on May 1 or 6 from Finn crossbred, Columbia, and Polypay ewes. Rams were introduced upon CIDR-G withdrawal. Of 59 CIDR-G-treated ewes, 58 exhibited estrus and 45 lambed. Twenty-three of 30 contemporary control ewes were bred, and 20 lambed.(ABSTRACT TRUNCATED AT 250 WORDS)
Wheaton
J E
JE
Department of Animal Science, University of Minnesota, St. Paul 55108.
Windels
H F
HF
Johnston
L J
LJ
D000282:Administration, Intravaginal; D000818:Animals; D003692:Delayed-Action Preparations; D004971:Estrus / Q000187:drug effects / Q000502:physiology; D005260:Female; D005298:Fertility / Q000187:drug effects; D005306:Fertilization / Q000187:drug effects; D008297:Male; D049590:Postpartum Period / Q000187:drug effects / Q000502:physiology; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology*; D012098:Reproduction / Q000187:drug effects*; D012621:Seasons; D012756:Sheep / Q000502:physiology*
D003692:Delayed-Action Preparations; D011374:Progesterone