Submitted to: American Dairy Science Association Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/9/2009
Publication Date: 7/12/2009
Citation: Heine, C.S., Kononoff, P.J., Pedersen, J.F., Geis, A.G., Gehman, A.M. 2009. FEEDING BROWN MIDRIB FORAGE SORGHUM SILAGE AND CORN GLUTEN FEED TO LACTATING DAIRY COWS. American Dairy Science Association Abstracts.
Technical Abstract: Brown midrib (BMR) forage sorghum contains less lignin , resulting in increased NDF digestibility compared to conventional sorghum . An experiment was conducted to evaluate the effects of BMR forage sorghum silage in diets containing wet corn gluten feed (WCGF). The objective was to determine the effect of diet on milk production, composition, and total tract digestibility. Twenty lactating Holstein cows weighing 729.8 ± 3.27 kg and averaging 124 ± 29.0 DIM were assigned one of the four dietary treatments: 1) conventional sorghum and 0% WCGF, 2) conventional sorghum and 30% WCGF, 3) BMR sorghum and 0% WCGF, and 4) BMR sorghum and 30% WCGF. The experimental design was a 4 x 4 Latin square in which each cow received each diet during 4 21-d periods. In diets containing no WCGF, 27% of the diet DM consisted of sorghum compared to diets containing WCGF, in which 17% of the diet DM consisted of sorghum. Ruminal NDF digestibility of sorghum silages were evaluated in vitro by incubating approximately 0.3 g of sample in rumen fluid for 48 h. The proportion of NDF digested after 48 h was significantly higher (P < 0.01) for the BMR sorghum (53.0 ± 1.7%) compared to the conventional sorghum (39.0 ± 0.78%). Compared to the conventional sorghum, feed intake tended (P = 0.07) to be higher when cows consumed BMR sorghum silage (24.6 vs. 25.95 ± 1.11 kg/d). In contrast, total tract NDF digestibility was lower when animals consumed diets containing BMR sorghum silage (54.5 vs. 57.0 ± 0.70%). The inclusion of WCGF did not affect DMI nor total tract NDF digestibility, and no interactions between silage type and WCGF were observed. Although cows consumed more of the rations containing BMR sorghum silage, no differences were observed in milk production or composition. Similarly, the inclusion of WCGF did not affect milk yield or composition. Across treatments, actual milk yield averaged¬¬¬ 30.5 + 1.63 kg/d and yield of milk fat and protein averaged 1.08 ± 0.06 kg/d and 0.90 ± 0.05 kg/d respectively. In spite of increased in vitro NDF digestibility and DMI, increases in milk production were not observed in cows consuming BMR sorghum silage and no interactions with WCGF were observed. Key Words: brown midrib, sorghum, wet corn gluten feed