IMPROVEMENT OF DAIRY FORAGE AND MANURE MANAGEMENT TO REDUCE ENVIRONMENTAL RISK
Location: Environmentally Integrated Dairy Management Research Unit
Title: Orchardgrass ley for improved manure management in Wisconsin: II. Nutritive value and voluntary intake by dairy heifers
Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 6, 2011
Publication Date: May 23, 2011
Citation: Hedtcke, J.L., Posner, J.L., Coblentz, W.K., Hall, J., Walgenbach, R.P., Davidson, J. 2011. Orchardgrass ley for improved manure management in Wisconsin: II. Nutritive value and voluntary intake by dairy heifers. Agronomy Journal. 103:1106-1114.
Interpretive Summary: Previously, it was demonstrated that an orchardgrass ley (a site established in grass and designated for repeated application of manure) was a highly productive source of forage, and it opened needed summer windows for the application of manure. This is especially valuable within the corn/alfalfa rotations common throughout Wisconsin. In these systems, there are only limited opportunities for manure spreading, which becomes increasingly problematic as confinement dairies become larger. In this study, orchardgrass hay produced from a frequently manured grass ley exhibited excellent forage quality characteristics, as well as high concentrations of phosphorus (P). The latter could reduce needed supplemental dietary P purchases. Concentrations of tissue potassium (K) also were high (32.0 g kg-1). Cool-season grasses receiving manure are notorious for luxury consumption of K, and this was observed in our work; therefore, feeding these hays in dry cow rations should be avoided. A feed rejection trial with Holstein heifers showed that the application of dairy slurry after each orchardgrass hay harvest did not increase forage rejection relative to hays grown with applications of commercial fertilizers. In the upper Midwest, this ley system would open several summer windows for spreading manure, as well as supply producers with an alternative forage to compliment their production of corn and alfalfa silages.
Confinement dairy feeding operations in the Upper Midwest could benefit from utilizing a wider range of forages than alfalfa (Medicago sativa L.) and corn silage (Zea mays L.). A short cycle, frequently manured, orchardgrass (Dactylis glomerata L.) ley (OG) was compared with corn silage (CS) in a 2 by 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. Three-yr average yields for manured OG and CS were 8.6 and 16.0 Mg dry matter (DM) ha-1, respectively. 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 diets the of dairy cows 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, concentrations were not significantly greater in the hay-production years relative to the seeding year. Forage rejection trials indicated that Holstein heifers (Bos taurus) did not prefer commercially fertilized OG over manured OG hays. These results indicate that a mobile 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.