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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2008-1579v1 87/6/1934    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Holm, D. E. Articles by Irons, P. C. PubMed PubMed Citation Articles by Holm, D. E. Articles by Irons, P. C.

The value of reproductive tract scoring as a predictor of fertility and production outcomes in beef heifers¹

Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Private Bag X04, Onderstepoort, 0110, South Africa

² Corresponding author: dietmar.holm{at}up.ac.za

In this study, 272 beef heifers were studied from just before their first breeding season (October 15, 2003), through their second breeding season, and until just after they had weaned their first calves in March, 2005. This study was performed concurrently with another study testing the economic effects of an estrous synchronization protocol using PG. Reproductive tract scoring (RTS) by rectal palpation was performed on the group of heifers 1 d before the onset of their first breeding season. The effect of RTS on several fertility and production outcomes was tested, and the association of RTS with the outcomes was compared with that of other input variables such as BW, age, BCS, and Kleiber ratio using multiple or univariable linear, logistic, or Cox regression. Area under the curve for receiver operating characteristic analysis was used to compare the ability of different input variables to predict pregnancy outcome. After adjustment for BW and age, RTS was positively associated with pregnancy rate to the 50-d AI season (P < 0.01), calf weaning weight (r = 0.22, P < 0.01), and pregnancy rate to the subsequent breeding season (P < 0.01), and negatively associated with days to calving (r = 0.28, P < 0.01). Reproductive tract scoring was a better predictor of fertility than was Kleiber ratio and similar in its prediction of calf weaning weight. It was concluded from this study that RTS is a predictor of heifer fertility, compares well with other traits used as a predictor of production outcomes, and is likely to be a good predictor of lifetime production of the cow.

Key Words: age at puberty • beef heifer • Kleiber ratio • pregnancy rate • reproductive tract scoring • weaning weight

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