40 Alternative forages for dairy heifers

Abstract

Abstract Dairy heifers have moderate energy needs with diets containing high proportions of corn silage, often exceeding needs of pregnant heifers. Use of moderate energy forages to decrease energy and increase NDF content has been successful to control intake and growth of pregnant heifers. Several forages could be used, including cereal grain forages/straws, warm season perennial grasses, sorghum forages, and corn stover. Higher NDF content diets control intake through rumen fill as heifers eat approximately 1% of bodyweight in NDF daily. Research at the University of Wisconsin found reduced intakes and more desirable gains for pregnant heifers fed diets that included either corn stover, wheat straw, or eastern gamagrass (0.8–1.0 kg gain/day) compared with heifers fed an alfalfa/corn silage diet (1.2 kg gain/day). A study feeding alfalfa stemlage also found that heifers had more desirable gains (0.9–1.0 kg/day) when fed diets with stemlage or straw than heifers fed an alfalfa/corn silage diet. Sorghum forages may also work to partially replace corn silage in the forage program, with an opportunity to double-crop with cereal grain forages. Wisconsin studies show that sorghum forages can have similar or greater yields than corn silage when planted in early to mid-June and harvested once in the fall, with sorghums being more responsive to irrigation and nitrogen than corn. Most sorghums had similar or greater yields than corn silage when fertilized at 22–45 kg N/acre or irrigated at 50–75% of levels recommended for corn. A recent study found heifers fed sorghum-sudangrass silage based diets had lower intakes due to higher NDF content leading to more optimal daily gains (0.9 kg/d) than heifers fed a corn silage/alfalfa silage/grass hay diet that had similar protein and energy content, but was lower in NDF content. Use of alternative forages can help control nutrient intake and thus growth, and can also help control costs and improve nutrient/manure management by lowering intakes and forage production costs.