A comparison of cow response to extensive vs. intensive overwintering management systems

Dry matter intake (DMI), enteric methane (CH ₄ ) emissions, and animal performance were compared over two, 21-day periods for pregnant beef cows receiving grass hay-based diets in drylot (DL) and bale grazing (BG) overwintering systems. The BG system included two supplementation strategies: non-supplemented (BGcon) and protein supplementation every third day using dried distiller grains with solubles (BGdg). Individual cow DMI was measured using a GrowSafe system for DL and the n-alkane marker technique for BGcon in the first period (P1). BGcon and DL had similar ( p = 0.47) DMI at 12.2 ± 0.98 and 13.4 ± 0.98 kg DM day ⁻¹ , respectively. Comparing all three treatments across two periods, cow ADG tended ( P > 0.08) to be greatest for DL and lowest for BGcon, with BGdg being intermediate. Enteric CH ₄ emissions (L day ⁻¹ ) for BGcon were greater ( P < 0.05) than BGdg in both periods, with emissions for DL being similar to BGdg in P1 and higher than BGdg in P2. Serum urea nitrogen concentrations were greatest for BGdg. Protein supplementation improved animal N status and enteric CH ₄ emissions in the BG system. The ability to measure individual cow intake improves our understanding of animal energy balance and production efficiency in extensive overwintering environments.