Disease & heat resistance

Hair Shedding Scores in an Angus Beef Polulation at High Elevation

---

Abstract

Hair shedding score (HSS) is a visual phenotypic measure used to evaluate how effectively beef cattle shed their winter coat in late spring or early summer. The Beef Improvement Federation (BIF) scoring system ranges from 1 (100% winter coat shed) to 5 (0% winter coat shed) and serves as an indicator of thermoregulation, adaptability, and productivity. Previous research has shown HSS to be a moderately heritable trait (h2 ≈0.34-0.40) associated with heat tolerance and improved performance in low-elevation herds. However, limited information exists on HSS variation and genetic influence among cattle raised at high elevation, where cold stress and large diurnal temperature shifts influence shedding patterns. The objective of this study was to investigate the relationship between hair shedding scores as an indicator trait for economically relevant traits in cattle that are raised at high elevation and in cooler climates. Hair shedding scores were recorded on 390 cows and 124 heifers managed under the same conditions at the John E. Rouse Ranch in Saratoga, Wyoming (2,195m elevation). This environment is atypical of most environments where HSS is recorded. For example, during scoring, ambient temperatures ranged from 7.8° to 27.8°C (heifers) and 12.2° to 32.2°C (cows). Cows and heifers were scored on June 20 and 30, 2025, respectively, by a single trained evaluator. Cows' scores ranged from 1 to 4, with the highest frequency at 2 (38%). Heifer scores also ranged from 1 to 4, with 30% scoring 4, suggesting differences in shedding patterns among younger animals. For cows, a linear model evaluating cow age at collection (groups defined as 3, 4, 5 to 9, and 10+ years of age) as a fixed effect showed significant variation among age classes(P < 0.001). Least-squares means (± SE) ranged from 3.32 ± 0.16 (3-year-olds) to 2.2 ± 0.07 (5-9-year-olds), indicating an age effect. When sire was added to the cow model, sire was a significant source of variation (P < 0.01). A secondary model evaluating age of calf (CA) at hair shed score collection (a proxy for interval between calving and HSS) and sire indicated that age of calf was not significant (P = 0.59), while cow age (P< 0.05) and sire (P< 0.001) continued to explain significant variation in HSS. In heifers, similar models were used. The first linear model evaluated heifer age (P < 0.001), but when sire effects were added, sire was the only effect found to be significant (P < 0.001). These results demonstrate that both cow age and sire contribute significantly to variation in HSS among high-elevation cattle. Additional analysis is determining the relationship between HSS and conception to AI, and the date of conception (natural service sires) in relation to hair shed score following the breeding season.

Keywords: 2026

How to Cite:

Autry, P., Enns, M., Griffin, M. & Speidel, S., (2026) “Hair Shedding Scores in an Angus Beef Polulation at High Elevation”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2285906. doi: https://doi.org/10.31274/wcgalp.23819

Rights: 1