Short-term treatment with a controlled internal drug releasing (CIDR) device and FSH to induce fertile estrus and increase prolificacy in anestrous ewes

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...

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Bibliographic Details
Published in:Theriogenology 2001-03, Vol.55 (5), p.1181-1191
Main Authors: Knights, M., Maze, T.D., Bridges, P.J., Lewis, P.E., Inskeep, E.K.
Format: Article
Language:English
Subjects:
anestrous ewe
Animals
CIDR
Drug Delivery Systems - veterinary
Estrus - drug effects
Estrus - physiology
Female
Follicle Stimulating Hormone - administration & dosage
FSH
Litter Size
Male
Ovulation Induction - methods
Ovulation Induction - veterinary
Pregnancy
Pregnancy Outcome - veterinary
Progesterone - administration & dosage
prolificacy
Random Allocation
Sheep - physiology
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Summary: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 of 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.
ISSN:0093-691X
1879-3231
DOI:10.1016/S0093-691X(01)00476-9