With spring bull-buying season approaching, Kansas State University cow-calf specialist Bob Weaber, PhD, reminds producers that calving-ease scores are a better selection tool than birthweights alone. Birthweight is an indicator trait for calving ease, accounting for 55 to 60 percent of variation. However, selecting for low birthweights can negatively affect weaning weights and yearling weights, and perhaps reduce calf survival when lightweight calves are born in cold, wet conditions. Calving ease, rather than birthweight, is the economically relevant trait associated with dystocia. Economically relevant traits, Weaber says, are those that directly generate revenue or incur costs in beef production systems. In the case of a commercial cow-calf producer, dystocia, or lack of calving ease, is what generates costs in a cow herd through direct losses of calves and their dams, increased labor costs and, certainly, lower reproductive rates among cows that have experienced dystocia. Calving-ease scores allow direct measurement of this economically relevant trait. Recording calving-ease scores is easy and should occur at or shortly after birth. Monitoring calving ease in heifers and cows will allow producers to select sires with optimal calving ease and moderate levels of birthweight, helping to minimize dystocia. The calving-ease records may also allow identification of sires that are causing problems. Sire selection for improved calving ease should focus on calving-ease EPDs. For sires of replacement females, consider using maternal calving-ease EPDs in your selection criteria. The Beef Improvement Federation recommends the scoring system included here, which also appears in NCBA IRM red books.
BIF Calving-ease Scores
1 No difficulty, no assistance
2 Minor difficulty, some assistance
3 Major difficulty, usually mechanical assistance
4 Caesarian section or other surgery
5 Abnormal presentation