Effects of feeding sorghum and oat silages on feed intake, milk production and composition, and enteric methane production in lactating dairy cows

Abstract Text: The objective of this experiment was to evaluate the production effects of replacing corn silage (serving as the control) with either sorghum or oat silage in the total mixed ration fed to lactating dairy cows. Twelve Holstein cows (days in milk 81 d ± 24; BW 615 kg ± 49.6) were used in a replicated 3 × 3 Latin square design experiment with 3, 28 d periods. Feeding was ad libitum for 5 to 10% refusals. The control diet consisted of (DM basis): 44% corn silage, 7.5% alfalfa haylage, 4% hay/straw mixture, 11% ground corn, 7.5% SoyPLUS (West Central Cooperative, Ralston, IA), 7.5% whole roasted soybeans, 7% canola meal, 4.5% molasses, 4% cottonseed hulls, and 3% mineral premix. For the sorghum diet, 22.7% (DM basis) of the corn silage in the diet was replaced with sorghum silage. Similarly, 22.7% of the corn silage in the oat diet was replaced with oat silage. The MP balance of the control, sorghum, and oat diets was 199, 238, and 290 g/d, respectively, whereas the balance of NE_l was 2.8, 2.4, and 2.8 Mcal/d. The forage sorghum (Alta AF 7202) was harvested on November 11, 2014 with the harvester set to 1 inch total chop length. The oats (Forage Plus) were mowed in a vegetative state and harvested on November 14, 2014. Sorghum and oat silages had DM of 30.5 and 30.8% and (DM basis): lactic acid, 2.89 and 7.27%; NDF, 62.7 and 54.7%; and CP, 9.5 and 11.7%, respectively. Enteric methane emission measurements were collected with the GreenFeed system. Control and oat diets resulted in higher DMI and milk yield than sorghum: 26.7, 27.1, vs 26.0 kg/d (SEM = 1.68, P = 0.02) and 39.6, 40.2, vs 38.7 kg/d (SEM = 3.57, P < 0.01), respectively. Methane emission (502 g/d; SEM = 26.7, P = 0.59) and milk fat yield (1.41 kg/d; SEM = 0.07, P = 0.78) were not affected by diet. The sorghum silage diet decreased milk true protein concentration (P = 0.03) compared with the control or oat silage (2.78 vs 2.85 and 2.83%, respectively). Similarly, milk protein yield was decreased (P = 0.05) by the sorghum diet (1.04 vs 1.13, and 1.13 kg/d, respectively). The results indicate that a 22.7% replacement of corn silage DM with oat silage is a viable alternative for dairy producers in the Northeast U.S. 

Keywords: sorghum, oats, silage