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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Impacts of estrus expression and intensity during a timed-AI protocol on variables associated with fertility and pregnancy success in &ITBos indicus&IT-influenced beef cows

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Rodrigues, A. D. [1] ; Cooke, R. F. [2] ; Cipriano, R. S. [3] ; Silva, L. G. T. [1] ; Cerri, R. L. A. [4] ; Cruppe, L. H. [5] ; Meneghetti, M. [6] ; Pohler, K. G. [7] ; Vasconcelos, J. L. M. [1]
Total Authors: 9
[1] Sao Paulo State Univ, UNESP, Sch Vet Med & Anim Sci, BR-18168000 Botucatu, SP - Brazil
[2] Texas A&M Univ, Dept Anim Sci, College Stn, TX 77845 - USA
[3] Unisalesiano Auxilium, BR-16016500 Aracatuba, SP - Brazil
[4] Univ British Columbia, Fac Land & Food Syst, Appl Anim Biol, Vancouver, BC V6T 1Z4 - Canada
[5] Select Sires Inc, Plain City, OH 43064 - USA
[6] Zoetis, BR-04711130 Sao Paulo, SP - Brazil
[7] Univ Tennessee, Dept Anim Sci, Knoxville, TN 37920 - USA
Total Affiliations: 7
Document type: Journal article
Source: JOURNAL OF ANIMAL SCIENCE; v. 96, n. 1, p. 236-249, JAN 2018.
Web of Science Citations: 3

This experiment evaluated the impacts of estrus expression and intensity, estimated by physical activity during a timed-AI protocol, on reproductive performance of Bos indicus-influenced beef cows. A total of 290 lactating, primiparous, and multiparous nonpregnant Nelore x Angus cows received a 2 mg injection of estradiol benzoate and an intravaginal progesterone (P4) releasing device (CIDR) on d -11, a 12.5 mg injection of PGF(2 alpha) on d -4, CIDR removal in addition to 0.6 mg injection of estradiol cypionate and 300 IU injection of eCG on d -2, and timed-AI on d 0. Cows were fitted with a pedometer behind their left shoulder on d -4. An estrus detection patch was attached to the tail-head of each cow on d -2. Pedometer results were recorded on d -2 and 0. Estrus expression was defined as removal of >50% of the rub-off coating from the patch on d 0. Net physical activity during estrus was calculated by subtracting total steps from d -4 to -2 (nonestrus basal activity) from total steps from d -2 to 0 (proestrus + estrus period) of each cow. Cows that did not express estrus were classified as NOESTR. Cows that expressed estrus were ranked by net physical activity; those above the median were classified as HIESTR and the remaining cows as LWESTR. Ovarian ultrasonography was performed on d 0 and 7. Blood was collected on d 0, 7, 20, and 30. Pregnancy status was verified by ultrasonography on d 30. Only data from cows responsive to the estrus synchronization protocol were utilized (NOESTR, n = 59; LWESTR, n = 100; HIESTR, n= 98). Diameter of dominant follicle on d 0, corpus luteum volume on d 7, and plasma P4 concentrations on d 7 were greater (P <= 0.05) in HIESTR vs. LWESTR and NOESTR and also greater (P <= 0.05) for LWESTR vs. NOESTR. Plasma P4 concentrations on d 0 were greater (P < 0.01) in NOESTR vs. HIESTR and LWESTR and similar (P = 0.93) between HIESTR and LWESTR. Whole blood mRNA expression of myxovirus resistance 2 on d 20 was greater (P <= 0.05) in HIESTR vs. LWESTR and NOESTR, and similar (P = 0.72) between LWESTR and NOESTR. Pregnancy rates were less (P <= 0.04) in NOESTR vs. HIESTR and LWESTR (52.4%, 68.9%, and 73.5%, SEM = 7.2), and similar (P = 0.57) between HIESTR and LWESTR. Hence, expression of estrus during a timed-AI protocol improved ovarian dynamics and pregnancy success, whereas estrus intensity modulated key biological markers associated with fertility but not pregnancy rates in B. indices-influenced cows beef cows. (AU)

FAPESP's process: 16/18460-6 - Impacts of estrus expression and intensity during estrus synchronization + artificial insemination protocol on parameters associated with fertility and pregnancy establishment in beef females
Grantee:Rafael Silva Cipriano
Support type: Regular Research Grants
FAPESP's process: 16/18216-8 - Collaborating with Oregon State University (USA) on research to enhance reproductive performance of beef females
Grantee:José Luiz Moraes Vasconcelos
Support type: Research Grants - Visiting Researcher Grant - International