136 Evaluation of the Relationship Between Hair Coat Shedding Ability, Apparent Forage Digestibility, and Mineral Status in Angus Cattle

Abstract

Abstract The objective of this study was to evaluate the relationship between winter hair coat shedding ability, apparent forage digestibility, and mineral status in Angus females. Data were collected on fall calving purebred Angus females with calves from March until July in 2019 (n = 10), 2020 (n = 31), 2021 (n = 39), and 2022 (n = 41). Dams were observed once monthly by two trained technicians for winter hair coat shedding and were given a visual score of 1 to 5 with 1 indicating complete shed and 5 indicating no shedding of the winter hair coat. Month of first shed (MFS) was determined when a female reached an average winter hair shedding score of > 3.5 for any given month. Fecal samples were collected during the grazing months of March, May, and July for 5 consecutive days and were then analyzed via proximate analysis to calculate apparent digestibility of dry matter (DM), ash, acid detergent fiber (ADF), and neutral detergent fiber (NDF) of forage. Liver and blood plasma samples were collected during the grazing months of March and July and analyzed via ICP-OES for mineral concentrations of K, Ca, Mg, Na, Fe, and Zn. Data were analyzed using the MIXED procedure of SAS with a significance declared at P < 0.05. The model included MFS, grazing month, and MFS by grazing month interaction. Interactions of MFS by month were observed for DM, NDF, ADF and liver Fe concentration. For DM, NDF, and ADF, within the grazing month of May, individuals with MFS in April and May were similar and greater when compared with June and July which were similar. Interpretation of these results show no clear trend of an association between hair shedding ability and apparent digestibility; however, some differences based on MFS existed. Further research into this area is important in understanding changes in overall cow performance due to adaptability.