Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2007
Publication Date: 11/4/2007
Citation: Coblentz, W.K., Davidson, J.A., Walgenbach, R.P., Posner, J.L., Hedtcke, J.L. 2007. Effects of Application of Dairy Slurry on Voluntary Intake of Orchardgrass Hays by Growing Dairy Heifers [abstract]. ASA-CSSA-SSSA Annual Meeting Abstracts. Paper No. 77-5. Interpretive Summary:
Technical Abstract: Many dairy production systems have a critical need for available sites to land apply dairy slurry after spring planting and during the summer months. One potential option is to apply these nutrients on perennial grass sods; however, this approach is viable only if voluntary intake by livestock is not affected. Dairy slurry or commercial fertilizer were applied at rates that delivered 53 and 56 kg N/ha, respectively, to ‘Elsie' orchardgrass in early April, and immediately after second cutting. Orchardgrass from the first (14 May; early heading stage) and third (14 July; vegetative regrowth) cuttings was harvested as dry hay, and stored under roof in 1.2 x 1.5-m round bales. Hays were offered to eight (483 ± 37.6-kg) Holstein heifers in (two) parallel Latin squares with a 2 x 2 factorial arrangement of treatments. Hays made from vegetative regrowth had numerically greater NDF (614 vs. 578 g/kg), and poorer 48-h NDF digestibility (671 vs. 725 g/kg NDF) than hays made from early-headed forage, while manured forages exhibited greater CP (164 vs. 134 g/kg) than commercially fertilized hays. Intakes of DM and organic matter (OM) were not affected by fertilization method or the interaction of main effects (P > 0.331), and intakes of NDF were not affected by any treatment factor (P > 0.111; mean = 11.9 g/kg BW). Intakes of DM (20.7 vs. 19.4 g/kg BW) and OM (18.7 vs. 17.2 g/kg BW) from early-headed hays were greater (P < 0.015) than vegetative regrowth; however, greater intakes of CP (P = 0.014), K (P = 0.002), Ca (P = 0.001), and Mg (P < 0.001) were observed for vegetative regrowth. Application of dairy slurry resulted in greater intakes of CP (P < 0.001), K (P = 0.002), and Mg (P = 0.002) than observed for commercially fertilized hays. Generally, intakes were primarily affected by harvest date, and effects of frequent manuring were relatively minor.