Rangeland Habitat Use and Activity of Cattle with Divergent Molecular Breeding Values for Residual Feed Intake

Abstract: Selection for the trait residual feed intake (RFI) is an emerging tool for cattle producers to manage feed costs within the beef industry. This study explored whether cattle habitat use and activity on extensive pasture-based systems in the dry mixedgrass of Alberta differed between cattle with divergent molecular breeding values (MBV’s) for RFI. Neither predicted RFI group (low vs. high) nor individual animal MBV score were found to explain cattle movement rates, resting time, or habitat use. Instead, timing of grazing (early, middle and late growing season grazing), pasture type (native mixedgrass, tame, or wetland plant community types), forage metrics (quantity and quality) and distance to water were the factors regulating cattle activity, habitat use, and performance. Cows had significantly higher activity levels (greater movement rates and lying bout frequency, less time spent lying down) early in the grazing season. Lying time decreased with increasing pasture size across all pasture types and native grasslands alone, and decreased with increasing biomass and exposure to better quality (less fibrous) grasses and forbs. Cow performance metrics during the growing season (weight and back fat gain, as well as calf weaning percentage) were not affected by MBV for RFI, activity measures or most habitat metrics studied. However, those cows spending less time within 200 m of water were found to wean larger calves and gain more back fat over the grazing season. I conclude that improving pasture-based cow/calf production through selection for low RFI requires more research into genetic markers that better predict RFI under these complex, native pasture environments. Our research showed that changing environmental conditions affected animal activity and habitat selection, and this consequently affected their performance. These results support that the identification of MBV markers unique to extensive production systems may be necessary to improve cow/calf production through selection using RFI.