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3038711 
Journal Article 
Short-term treatment with a controlled internal drug releasing (CIDR) device and FSH to induce fertile estrus and increase prolificacy in anestrous ewes 
Knights, M; Maze, TD; Bridges, PJ; Lewis, PE; Inskeep, EK 
2001 
1 
Theriogenology
ISSN: 0093-691X 
55 
5 
1181-1191 
11322244 
WOS:000168077000013 
The objectives were to evaluate, in anestrous ewes, the effectiveness of a CIDR-G device (0.3 g progesterone) administered for 5 d to induce estrus; and FSH (Folltropin; 55 mg NIH-FSH-P1 equivalent) in saline:propylene glycol (1:4) 24 h before insert removal (Day 0), to increase ovulation rate and prolificacy. Ewes of mixed breeding were assigned at random to 3 treatments: control (C; n = 125), 5 d progesterone (P5; n = 257) and 5 d progesterone plus FSH (P5F; n = 271). Intact rams were joined at insert removal and ewes were observed every 24 h for 3 d. On Day 14, the ovulation rates of all ewes detected in estrus in the treated groups were determined using transrectal ultrasonography. Rams were removed on Day 26 to 31, Ewes were examined for pregnancy then, and again 20 to 25 d later to detect ewes that conceived to the second service period. Percentage of ewes marked by rams was higher in progesterone-treated (77%) than in C (20%; P < 0.01), but did not differ between P5 and P5F. The ovulation rate (1.95 0.04) did not differ due to FSH. Conception (68%) and pregnancy (52%) rates were higher in progesterone-treated (P < 0.01) than in C (0%) ewes. Estrous response varied quadratically with time after ram introduction, and the conception rate varied quadratically with the time of observation of onset of estrus. Over two service periods more progesterone-treated than C ewes lambed (65 vs 45%; P < 0.01). Lambs born per ewe exposed (0.7 +/- 0.1, 1.0 +/- 0.1, and 1.1 +/- 0.1 for C, P5 and P5F, respectively) was increased by progesterone (P < 0.05). Litter size to the first service period (1.59 0.04) and overall (1.54 +/- 0.03) did not differ among treatment groups. FSH-treated ewes tended to have more lambs (1.67 +/- 0.1) than did ewes receiving progesterone alone (1.5 +/- 0.1; P = 0.06) and than did ewes lambing to the second service period (1.5 +/- 0.1; P = 0.06). In summary, a 5-d progesterone pre-treatment of anestrous ewes induced estrous cycles and increased the pregnancy rates. A single injection of FSH only tended to increase litter size. (C) 2001 by Elsevier Science Inc. 
CIDR; anestrous ewe; FSH; prolificacy