Pre-breeding blood urea nitrogen concentration and reproductive performance of Bonsmara heifers within different management systems

Show simple item record

dc.contributor.author Tshuma, Takula
dc.contributor.author Holm, D.E. (Dietmar Erik)
dc.contributor.author Fosgate, Geoffrey T.
dc.contributor.author Lourens, D.C. (Dirk Cornelius)
dc.date.accessioned 2015-03-18T12:45:14Z
dc.date.available 2015-03-18T12:45:14Z
dc.date.issued 2014-08
dc.description.abstract This study investigated the association between pre-breeding blood urea nitrogen (BUN) concentration and reproductive performance of beef heifers within different management systems in South Africa. Bonsmara heifers (n= 369) from five herds with different estimated levels of nitrogen intake during the month prior to the commencement of the breeding season were sampled in November and December 2010 to determine BUN concentrations. Body mass, age, body condition score (BCS) and reproductive tract score (RTS) were recorded at study enrolment. Trans-rectal ultrasound and/or palpation was performed 4–8 weeks after a 3- month breeding season to estimate the stage of pregnancy. Days to pregnancy (DTP) was defined as the number of days from the start of the breeding season until the estimated conception date. Logistic regression and Cox proportional hazards survival analysis were performed to estimate the association of pre-breeding BUN concentration with subsequent pregnancy and DTP, respectively. After stratifying for herd and adjusting for age, heifers with relatively higher prebreeding BUN concentration took longer to become pregnant when compared to those with relatively lower BUN concentration (P=0.011). In the herd with the highest estimated nitrogen intake (n=143), heifers with relatively higher BUN were less likely to become pregnant (P=0.013) and if they did, it was only later during the breeding season (P=0.017), after adjusting for body mass. These associations were not present in the herd (n=106) with the lowest estimated nitrogen intake (P>0.500). It is concluded that Bonsmara heifers with relatively higher pre-breeding BUN concentration, might be at a disadvantage because of this negative impact on reproductive performance, particularly when the production system includes high levels of nitrogen intake. en_ZA
dc.description.embargo 2015-08-31 en_ZA
dc.description.librarian hb2015 en_ZA
dc.description.sponsorship Faculty of Veterinary Science, University of Pretoria en_ZA
dc.description.uri http://link.springer.com/journal/11250 en_ZA
dc.identifier.citation Tshuma, T, Holm, DE, Fosgate, GT & Lourens, DC 2014, 'Pre-breeding blood urea nitrogen concentration and reproductive performance of Bonsmara heifers within different management systems', Tropical Animal Health and Production, vol. 46, no. 6, pp. 1023-1030. en_ZA
dc.identifier.issn 0049-4747 (print)
dc.identifier.issn 1573-7438 (online)
dc.identifier.other 10.1007/s11250-014-0608-3
dc.identifier.uri http://hdl.handle.net/2263/44047
dc.language.iso en en_ZA
dc.publisher Springer en_ZA
dc.relation.requires Adobe Acrobat Reader en
dc.rights © Springer Science+Business Media Dordrecht 2014.The original publication is available at : http://link.springer.comjournal/11250 en_ZA
dc.subject Beef cattle en_ZA
dc.subject Blood urea nitrogen en_ZA
dc.subject Reproductive performance en_ZA
dc.subject Nitrogen supplementation en_ZA
dc.subject Days to pregnancy (DTP) en_ZA
dc.title Pre-breeding blood urea nitrogen concentration and reproductive performance of Bonsmara heifers within different management systems en_ZA
dc.type Postprint Article en_ZA


Files in this item

This item appears in the following Collection(s)

Show simple item record