Variability in Weight Gains of Cows and Their Calves Across Grazing Management and Dam Age Class: Implications for Maternal Productivity

Abstract

Many beef producers in commercial rangelands rely on cow-calf operations. Unlike stocker operations, which typically seek to increase the weight of each animal over a grazing season, cow-calf producers often consider maternal productivity—the performance of both dam and calf—which affects a cow's lifetime reproductive output and longevity. Generally speaking, longer productive lives for cows reduce herd turnover and decrease costs for the producer. As rangeland grazing management strategies are evaluated, it is important also to consider their effects on maternal productivity, not just season-long weight gains. We compared 3 yr of cow and calf weight gains by dam age class to inform how patch-burn grazing, continuous grazing without fire, and rotational grazing might affect maternal productivity in an experimental Angus cow-calf herd in central North Dakota, United States. Overall, grazing management strategy explained variation in weight gain among cows, and dam age class explained variation in calf weight gains, leading us to conclude that mature cows (those with 4+ calves) on patch-burning and continuously grazed pastures had higher maternal productivity than cow-calf units on rotational grazing. When considered alongside previously published evidence that burned areas provided approximately twice as much net energy for maintenance, our data suggest that maternal productivity might be greatest among mature cows on patch-burned pastures, but this remains speculative until the actual intake of metabolizable energy for each cow-calf unit can be determined. These findings contribute further evidence of the potential for marginal gains to be found in grazing burned rangeland, with potentially direct positive effects on the financial viability of cow-calf operations.