Impacts of estrus expression and intensity during a timed-ai protocol on variables associated with fertility and pregnancy success in bos indicus-influenced beef cows1

dc.contributor.authorRodrigues, A. D. [UNESP]
dc.contributor.authorCooke, R. F.
dc.contributor.authorCipriano, R. S.
dc.contributor.authorSilva, L. G.T. [UNESP]
dc.contributor.authorCerri, R. L.A.
dc.contributor.authorCruppe, L. H.
dc.contributor.authorMeneghetti, M.
dc.contributor.authorPohler, K. G.
dc.contributor.authorVasconcelos, J. L.M. [UNESP]
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionTexas A&M University
dc.contributor.institutionUnisalesiano Auxilium
dc.contributor.institutionUniversity of British Columbia
dc.contributor.institutionSelect Sires Inc
dc.contributor.institutionUniversity of Tennessee
dc.description.abstractThis 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 × 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 PGF2α 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 (proes-trus + 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. indicus-influenced cows beef cows.en
dc.description.affiliationSchool of Veterinary Medicine and Animal Science São Paulo State University (UNESP)
dc.description.affiliationDepartment of Animal Science Texas A&M University
dc.description.affiliationUnisalesiano Auxilium
dc.description.affiliationApplied Animal Biology Faculty of Land and Food Systems University of British Columbia
dc.description.affiliationSelect Sires Inc
dc.description.affiliationDepartment of Animal Science University of Tennessee
dc.description.affiliationUnespSchool of Veterinary Medicine and Animal Science São Paulo State University (UNESP)
dc.identifier.citationJournal of Animal Science, v. 96, n. 1, p. 236-249, 2018.
dc.relation.ispartofJournal of Animal Science
dc.rights.accessRightsAcesso aberto
dc.subjectBeef cows
dc.subjectEstrus expression
dc.subjectEstrus intensity
dc.subjectPhysical activity
dc.titleImpacts of estrus expression and intensity during a timed-ai protocol on variables associated with fertility and pregnancy success in bos indicus-influenced beef cows1en


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