Master of Science / Department of Animal Sciences and Industry / Jeffrey S. Stevenson / Lactating dairy cows from 2 Kansas farms were used to determine the effectiveness of
exogenous progesterone in the form of an intravaginal insert (controlled internal drug release;
CIDR) in conjunction with an ovulation-synchronization protocol. Cows were enrolled in a
Presynch + Ovsynch protocol after parturition, where they received 2 injections of PGF[subscript]2[alpha], 14 d
apart (Presynch) beginning between 30 and 36 DIM. Cows (n = 155) detected in estrus after the
second PGF[subscript]2[alpha] injection of Presynch were inseminated (early AI). Remaining cows were
assigned randomly to be treated with the Cosynch-72 protocol (GnRH 12 d after last Presynch
PGF[subscript]2[alpha] injection, PGF[subscript]2[alpha] 7 d after GnRH, and timed AI + GnRH injection 72 h later) and served as
controls (n = 159), or to be treated with the Cosynch-72 protocol and receive a progesterone
insert (Ovsynch + CIDR; n = 175) for 7 d between GnRH and PGF[subscript]2[alpha]. Blood was collected at d
−22 and −10 (relative to TAI at d 0) to determine cycling status based on progesterone
concentrations and again at d 11 post AI to determine luteal competency. Treated cows were
assigned body condition scores (BCS) on d −22 and −10. Pregnancy status was confirmed by
palpation of the uterus per rectum and its contents on d 38 post-timed AI and verified again 4 wk
later. Treatment with the progesterone insert increased timed AI pregnancies per AI in Cosynch-
72 + CIDR-treated cows when compared with controls (38 vs. 24%), but did not differ from
early AI cows (38%). Pregnancy loss was numerically less in progesterone-treated cows than in
controls (4.4 vs. 11.8%). Our study shows that increased pregnancies per AI can be achieved by
the use of a progesterone insert in a reduced population of cows not yet inseminated, but treated
with a progesterone insert.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/872 |
| Date | January 1900 |
| Creators | Martel, Cynthia Ann |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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