Exposure of prepubertal beef bulls to cycling females does not enhance sexual development

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dc.contributor.author Fike, Karol E.
dc.contributor.author Miller, N. A.
dc.date.accessioned 2015-05-18T12:10:59Z
dc.date.available 2015-05-18T12:10:59Z
dc.date.issued 2015-05-18
dc.identifier.uri http://hdl.handle.net/2097/19251
dc.description.abstract The objective of this study was to determine whether continuous, long-term, fenceline exposure of prepubertal beef bulls to cycling beef females reduced age at puberty and influenced the percentage of bulls that passed an initial breeding soundness examination (BSE). Bulls (Angus, N = 37; Simmental, N = 22; Hereford, N = 10; Simmental x Angus, N = 8) averaging 202 ± 21.5 d of age were given either continuous fenceline and visual exposure to cycling females (Exposed: N= 41) or no exposure (Control: N=36). Estrus was induced in cycling beef females so at least 3 females were in standing estrus each week during the 182 d of exposure to bulls. Scrotal circumference (SC), body weight, and blood samples were collected every 28 d. When bulls had SC ≥ 26 cm, semen samples were obtained monthly via electroejaculation until puberty was achieved (≥ 50 x 106 sperm/mL with at least 10% progressive motility). Behavioral observations were conducted twice monthly, once when females were in estrus and once during diestrus. Homosexual mounting, flehmen responses, and number of times near penned females were recorded for each observation period. Breeding soundness examinations were conducted when bulls averaged 364 ± 21.5 d of age. Normal sperm morphology of at least 70% and sperm motility of at least 30% were required to pass the BSE. Age, body weight, and SC at puberty did not differ between Exposed and Control bulls (320 ± 28 d and 311 ± 29 d; 466.2 ± 12.2 and 437.7 ± 13.5 kg; and 34.4 ± 2.5 cm and 34.9 ± 2.5 cm, respectively). Percentage of bulls passing their initial BSE did not differ between treatments (Exposed: 87.8%, Control: 75.0%). Treatment, month, and female estrous stage interacted (P = 0.05) to affect the number of mount attempts and flehmen responses. Exposed bulls entered the cow area more times (P < 0.001) during estrus than diestrus in months one, two and three. We concluded that bulls given 3 continuous, long-term, fenceline exposure to cycling beef females do not have enhanced sexual development. en_US
dc.language.iso en_US en_US
dc.relation.uri http://www.theriojournal.com/article/S0093-691X(14)00207-6/abstract en_US
dc.rights NOTICE: this is the author's version of a work that was accepted for publication in . 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 Theriogenology, [82, 3, (2014)] 10.1016/j.theriogenology.2014.05.001 en_US
dc.subject Beef bull en_US
dc.subject Behavior en_US
dc.subject Breeding soundness examination en_US
dc.subject Female exposure en_US
dc.subject Puberty en_US
dc.subject Sexual development en_US
dc.title Exposure of prepubertal beef bulls to cycling females does not enhance sexual development en_US
dc.type Article (author version) en_US
dc.date.published 2014 en_US
dc.citation.doi 10.1016/j.theriogenology.2014.05.001 en_US
dc.citation.epage 454 en_US
dc.citation.issue 3 en_US
dc.citation.jtitle Theriogenology en_US
dc.citation.spage 447 en_US
dc.citation.volume 82 en_US
dc.contributor.authoreid karol en_US


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