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|Title: ||Evaluation of protocols to synchronize estrus and ovulation in seasonal calving pasture-based dairy production systems|
|Authors: ||Herlihy, Mary M.|
Berry, Donagh P.
Crowe, Mark A
Diskin, Michael G.
Butler, Stephen T.
|Keywords: ||Estrous synchronization|
|Issue Date: ||Sep-2011|
|Publisher: ||Elsevier Inc and American Dairy Science Association|
|Citation: ||M.M. Herlihy, D.P. Berry, M.A. Crowe, M.G. Diskin, S.T. Butler. Evaluation of protocols to synchronize estrus and ovulation in seasonal calving pasture-based dairy production systems. Journal of Dairy Science, 94 (9), September 2011: 4488–4501. DOI:10.3168/jds.2010-4126|
|Series/Report no.: ||Journal of Dairy Science;vol. 94|
|Abstract: ||Lactating dairy cows (n = 1,538) were enrolled in a randomized complete block design study to evaluate protocols to synchronize estrus and ovulation. Within each herd (n = 8), cows were divided into 3 calving groups: early, mid, and late, based on days in milk (DIM) at mating start date (MSD). Early calving cows (n = 1,244) were ≥42 DIM at MSD, mid-calving cows (n = 179) were 21 to 41 DIM at MSD, and late-calving cows (n = 115) were 0 to 20 DIM at MSD. Cows in the early, mid-, and late-calving groups were synchronized to facilitate estrus or timed AI (TAI) at MSD (planned breeding 1; PB1), 21 d (PB2), and 42 d (PB3) after MSD, respectively. For each PB, cows in the relevant calving group were stratified by parity and calving date and randomly assigned to 1 of 4 experimental groups: (1) d −10 GnRH (10 μg of i.m. buserelin) and controlled internal drug release insert (CIDR; 1.38 g of progesterone); d −3 PGF2α (25 mg of i.m. dinoprost); and d −2 CIDR out and AI at observed estrus (CIDR_OBS); (2) same as CIDR_OBS, but GnRH 36 h after CIDR out and TAI 18 h later (CIDR_TAI); (3) same as CIDR_TAI, but no CIDR (Ovsynch); or (4) untreated controls (CTRL). The CIDR_OBS, CIDR_TAI, and Ovsynch had shorter mean intervals from calving to first service compared with the CTRL (69.2, 63.4, and 63.7 vs. 73.7 d, respectively). Both CIDR_OBS (predicted probability; PP of pregnancy = 0.59) and CIDR_TAI (PP of pregnancy = 0.54) had increased odds of conceiving at first service compared with Ovsynch [PP of pregnancy = 0.45; odds ratio (OR) = 1.81 and OR = 1.46, respectively], and Ovsynch had decreased likelihood of conceiving at first service (OR = 0.70) compared with CTRL (PP of pregnancy = 0.53). Both CIDR_TAI hazard ratio; HR [95% confidence interval = 1.21 (1.04, 1.41)] and Ovsynch [HR (95% confidence interval) = 1.23 (1.05, 1.44)] were associated with an increased likelihood of earlier conception compared with the CTRL. A greater proportion of cows on the CIDR_TAI treatment successfully established pregnancy in the first 42 d of the breeding season compared with the CTRL (0.75 vs. 0.67 PP of 42-d pregnancy, respectively). Protocols to synchronize estrus and ovulation were effective at achieving earlier first service and conception in pasture-based seasonal calving dairy herds. However, animals that conceived following insemination at observed estrus had a decreased likelihood of embryo loss to first service compared with animals bred with TAI (PP of embryo loss after first service = 0.05 vs. 0.09; OR = 0.52).|
This is the author’s version of a work that was accepted for publication in Journal of Dairy Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Dairy Science, Volume 94 (9), September 2011: 4488–4501. DOI:10.3168/jds.2010-4126
|Appears in Collections:||Animal & Bioscience|
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