268 Environmental impacts from cattle consuming tannin-containing hays

Abstract

The cow-calf phase accounts for approximately 80% of total greenhouse gas emissions attributed to beef production systems. There is potential for tannin-containing hays to reduce these environmental impacts. Fifteen mature beef brood cows and 9 yearling beef heifers were blocked by weight and randomly assigned to 3 groups of 5 cows or 3 heifers and fed tannin-containing (bird's-foot trefoil-BFT, sainfoin-SAN, small burnet-SML) or non-tannin-containing (alfalfa-ALF, cicer milkvetch-CMV, meadow bromegrass-MB) hays in 4 trials. Groups of cows were fed BFT, CMV, or MB in Trial 1 and ALF, SAN, or SML in Trial 3. Groups of heifers were fed ALF, MB, or SAN in Trial 2 and BFT, CMV, or SML in Trial 4. Each trial used a completely randomized block design with repeated measures during 5 days following a 14-d adjustment period. Nine cows and 9 heifers were selected for total collection of enteric methane using the SF6 methodology, feces, and urine while intake was measured for all animals. Methane emission from cows was lower for SML than ALF (P = 0.04) or SAN (P = 0.03; Table 268). Additionally, cows and heifers fed tannin-containing hays had lower urine urea nitrogen (UUN) and blood urea nitrogen (BUN) than animals fed non-tannin-containing hays (Table 268), suggesting a shift in nitrogen excretion from urine to feces. In conclusion, tannin-containing legumes consumed as hays have the potential to reduce environmental impacts attributed to cattle fed in confinement. a-cMeans in a row with different superscripts differ (P < 0.1). a-cMeans in a row with different superscripts differ (P < 0.1).