Abstract #257

Section: Ruminant Nutrition
Session: Ruminant Nutrition II
Format: Oral
Day/Time: Monday 2:15 PM–2:30 PM
Location: 321
# 257
Effects of feeding brown midrib dwarf pearl millet silage on lactational performance and enteric methane emission in dairy cows.
M. T. Harper*1, A. Melgar1, G. Roth1, A. N. Hristov1, 1The Pennsylvania State University, University Park, PA.

The objective of this experiment was to evaluate the production effects of replacing corn silage (CS; serving as the control) with brown midrib dwarf pearl millet silage (PM) in the total mixed ration of lactating dairy cows. Sixteen Holstein cows (65 ± 21 DIM; BW 630 ± 71 kg) were used in a replicated 2 × 2 Latin square design experiment with two 28-d periods. Feeding was ad libitum for 5 to 10% refusals. The control diet consisted of (DM basis): 50% CS, 6% alfalfa haylage, 4% hay/straw mixture, and 40% concentrate feeds. For the PM diet, 20% of CS was replaced with PM (on DM basis). Control and PM diets were 16.7 and 17.2% CP, 30.3 and 32.4% NDF, and 28.0 and 24.1% starch, respectively. Metabolizable protein balance of control and PM diets was 27 and 208 g/d, respectively; NEL balance was −0.7 and −0.5 Mcal/d. Enteric methane emission was measured using the GreenFeed system. The PM diet resulted in equal DMI as the control (29.0 vs 29.1 kg/d; SEM = 0.65, P = 0.78, respectively) but lower milk yield (49.6 vs 51.3 kg/d; SEM = 2.02, P < 0.001) and lower feed efficiency (1.72 vs 1.77 kg/ kg milk; SEM = 0.05, P = 0.01). Energy corrected milk (ECM) yield (46.7 kg/d; SEM = 1.92, P = 0.86), and ECM feed efficiency were not different between diets. The PM diet tended to increase milk fat content compared with the control diet (3.71 vs 3.47%; SEM = 0.118, P = 0.06, respectively) but true protein and lactose content were not affected. Yields of the individual milk components were not affected (P ≥ 0.23) by diet and averaged 1.81 kg/d fat, 1.45 kg/d true protein and 2.51 kg/d lactose. Enteric methane emission was increased by the PM diet over the control (454 vs 396 g/d; SEM = 18.4, P < 0.001) as was methane yield (15.7 vs 13.8 g/DMI; SEM = 0.54, P = 0.001) and methane intensity (9.6 vs 8.3 g/kg ECM; SEM = 0.39, P = 0.001). Brown midrib dwarf pearl millet silage has potential to partially replace CS in the diet of dairy cattle without affecting ECM yield and milk components. This replacement, however, is likely to increase enteric methane emission.

Key Words: pearl millet, methane, dairy cow