Orchardgrass Ley for Improved Manure Management in Wisconsin: II. Nutritive Value and Voluntary Intake by Dairy Heifers

Abstract

Confinement dairy feeding operations in the Upper Midwest could benefit from using a wider range of forages than alfalfa (Medicago sativa L.) and corn silage (Zea mays L.). A short‐term ley of orchardgrass (Dactylis glomerata L.) (OG) frequently treated with manure, was compared with corn silage (CS) in a 2 × 2 factorial trial conducted across 3 yr at two locations in Wisconsin. Nutrients were applied as either manure (M) or fertilizer (F) to meet crop N needs. Weighted on the basis each cut contributed to the total annual yield of OG, concentrations of crude protein (163 g kg−1) and 48‐h neutral detergent fiber (NDF) digestibility (657 g kg−1 NDF) were suitable for incorporation into the diets of dairy cows (Bos taurus) and replacement heifers. Tissue concentrations of P and K were 3.7 and 32.0 g kg−1, respectively. High tissue concentrations of P can help with soil‐test P drawdown, and reduce purchases of supplemental dietary P. Although heavy manuring resulted in high tissue K, especially in late‐season cuts, K concentrations were not significantly greater in the hay‐production years relative to the seeding year in either M or F. Based on results with 483 ± 37.6 kg Holstein heifers, there were no differences in voluntary intake by heifers offered commercially fertilized compared to manured OG hays. These results indicate that an OG ley system could be part of a larger alfalfa–corn silage rotation, providing confinement dairies with an alternative forage option, and additional manuring opportunities during summer months.