Effects of partially replacing corn silage with brown midrib male-sterile sorghum silage on intake, digestibility, and milk production in dairy cows

Sorghum, a drought-tolerant crop, may serve as a promising forage alternative to corn in water-scarce regions. The study objective was to assess the effect of replacing conventional (nonbrown midrib) corn silage (CCS) with brown midrib male-sterile sorghum silage (BMR-MS-SS) at replacement rates of 0% (control), 25% (25%-BMR-MS-SS), and 50% (50%-BMR-MS-SS) on apparent total-tract nutrient digestibility (TTD), DMI, and ECM production. Compared with the control, protein concentrates and grass hay were decreased and dry ground corn increased in 25%-BMR-MS-SS and 50%-BMR-MS-SS to maintain similar nutrient composition among diets. Dietary treatments were randomly assigned to 48 cows and a subsample of 30 cows was randomly selected for TTD measurements. The 50%-BMR-MS-SS diet had the lowest TTD of DM, CP, starch, ADF, and NDF, which may be partially explained by its increased DMI. Compared with the control, the DMI of 25%-BMR-MS-SS and 50%-BMR-MS-SS diets were 12.7% and 11.4% greater, resulting in higher DMI as a percentage of BW, as well as increased milk and ECM yields. Dry matter intake and ECM were greater for cows fed 25%-BMR-MS-SS (26.6 and 44.4 kg/d) and 50%-BMR-MS-SS (26.3 and 43.7 kg/d) compared with the control cows (23.6 and 40.4 kg/d, respectively). We concluded that BMR-MS-SS can be a viable forage alternative to partially replace CCS in lactating dairy cow diets when diets are balanced for similar nutrient composition.