Lactation performance of Holstein dairy cows fed diets with or without an annual forage mix silage

Lay Summary Use of annual forage mixes (commonly sorghum-sudangrass, Italian ryegrass, and various cool-season legumes) in dairy cropping rotations have increased recently, however no research has been conducted to evaluate its use in dairy cattle rations and impacts on feed intake and milk production. We evaluated the use of an annual mix silage to replace the alfalfa-grass silage in diets of lactating dairy cows. The annual mix silage was lower in protein than the alfalfa-grass silage so supplemental protein was added to the diet. Cows fed the diet with annual mix silage had higher feed intake by the end of the 8-week study with no difference in energy corrected milk production, milk fat yield and protein yield. Fiber digestibility was improved for the annual mix silage diet which likely helped compensate for the diet being higher in fiber and lower in estimated energy. Based on these results, an annual forage mix harvested at a vegetative stage (70 to 100 cm height) would be suitable for use in lactating dairy cow diets. Appropriate diet formulation is needed to account for lower protein when sorghum-sudangrass makes up a significant part of the mix if replacing alfalfa-grass silage in the diet.