Performance and economics of fall grazing cover crops compared to a traditional drylot system of fall-calving cow-calf pairs

Abstract

The objective of this study was to evaluate cow and calf performance while strip grazing a cover crop mix consisting of radishes, turnips, oats, and common vetch (CC) compared to a traditional, drylot management system (CON) of the Iowa State University Beef Teaching Farm fall-calving herd. The study was repeated for 3 consecutive years to account for weather variation.  Each growing season presented a unique situation. With a targeted seeding date of August 1st each year, yields ranged from 2,750 – 4,830 lbs of dry matter per acre, averaging 3,952 lbs. The greatest yield was observed in 2019 while the lowest yield occurred in 2020 with drought conditions restricting growth. Growth in 2021 was intermediate, but peak yield occurred after grazing began due to a delayed killing frost. Turnout dates ranged from early-November to mid-December, and fall pairs grazed for an average of 32 days, ranging from 17 – 45 days.  Despite fluctuation in cow body weights between treatments over the years, calves on CC had equal to or greater average daily gain and final body weights compared to calves on CON. Over the 3 years, CC calves gained an average of 0.36 lbs more per head per day than their CON counterparts. This advantage may be a reflection of CC dams producing a higher quality milk due to the high-quality forage diet and the ability of calves to graze alongside their dam.  An economic analysis of the 3-year project revealed a 29% average reduction in calf cost of gain of cow-calf pairs grazing cover crops ($1.11/lbs of gain) compared to cow-calf pairs fed in a drylot setting ($1.57/lb of gain). Compared to the standardized drylot in this scenario, this efficiency boost emphasizes the value of extending the grazing season, especially in times of high feed costs.