References
Pre-breeding heifer examination and selection in UK beef herds
Abstract
The objective of this review is to evaluate examination tools and how they can be used to assess the breeding potential of beef heifers prior to service. Reproductive tract examination techniques, pelvic measurement, and antral follicle counts (AFC) are methods that are used and could be of value to farmers where they can either identify pubescent heifers and/or those with the best reproductive potential. Reproductive tract scoring (RTS) to assess the pubertal state and therefore reproductive status of replacement heifers is explored alongside further adaptions of this method. The use of pelvic measurement is considered: first, where a small pelvic area or an abnormal shaped pelvic inlet is identified, which may result in elimination from the breeding cohort to reduce the potential risk of dystocia and poor performance; and second, since it may be advocated for use in conjunction with other methods. AFC are included since they too may help identify the reproductive potential of heifers. Evaluation of these examination tools demonstrates that the use of modified RTS methods, to include ultrasound examination to detect the absence of a corpus luteum (CL), absence of a follicle ≥ 13 mm and the uterine horn diameter as well as pelvic measurements, could add value to heifer breeding soundness examinations (HBSE) when carried out.
It is widely recognised that bull breeding soundness examination should play a routine role in herd health preparation ahead of the service period. However, routine breeding soundness examination of eligible reproductive females is not commonplace in most UK beef herds. The future health, welfare, productivity and sustainability of the herd is reliant on selecting the most fertile, efficient and suitably sized replacement stock for breeding. Routine practices such as infectious disease monitoring, trace element and metabolic blood profiles, vaccination and nutritional management are key to maintaining a healthy, fertile herd. Breeding decisions are oft en based on important subjective measures such as docility, conformation, external frame, and selection of heifers from the best cows, alongside simple and traditional, objective selection targets such as age and weight at first service. Tools such as reproductive tract examination and pelvic measurements have been developed and adapted, and while they may require more time and skill to implement, they could still have a place in pre-breeding examinations. Reproductive tract scoring (RTS), however, was found to be a better predictor of reproductive performance compared with previously advocated measurements of bodyweight, body condition score (BCS) and the older Kleiber Ratio (Kleiber, 1947; Holm et al, 2009). Improved reproductive tract measurements (Holm et al, 2016) and objective pelvic measurement have been shown to add prognostic value for pregnancy failure and prognostic value for poor performing heifers respectively (Holm et al, 2016).
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