254 Digestibility of sheep offered tall fescue, meadow fescue and orchardgrass grasses ensiled with slurry or commercial urea fertilization

Abstract

Abstract Silage intake by ruminants can be affected by both fertilization and forage type. The objective of this study was to evaluate digestion by sheep offered three different grasses fertilized with either urea (C) or dairy slurry (S). Plots of meadow fescue (MF), tall fescue (TF) or orchardgrass (OG) were planted on 25 July 2017, and first harvested on 29 June 2018. Plots were then fertilized with urea (52 kg N/ha) or slurry (71,150 L/ha). A second harvest was baled 6 August at approximately 57% moisture and wrapped in plastic. Eighteen lambs (59 ± 1.5 kg) were allocated randomly to one of the 6 treatment combinations to provide 3 lambs per treatment within each of 3 periods consisting of a 10-d adaptation and 7-d total fecal and urine collection. Data were analyzed as a 2 × 3 factorial arrangement using PROC MIXED of SAS. Dry matter (DM) and organic matter (OM) intakes (g/kg BW) were greater (P < 0.05) from MF fertilized with C than from the other forage-fertility combinations. Digestibility of DM and OM were greater (P < 0.05) from MF vs. OG, and OG vs. TF. Digestibility of OM also was greater (P < 0.05) from C vs. S. Digestible DM and OM intakes (g/kg BW) were greatest (P < 0.05) from MF fertilized with C. In addition, digestible DM intake (g/kg BW) was greater (P < 0.05) for MF fertilized with S compared to TF fertilized with C, and digestible OM intake was greater (P < 0.05) for MF fertilized with S compared to OG fertilized with S. Therefore, urea-fertilized meadow fescue may improve energy intake compared with that from orchardgrass or tall fescue, but fertilization of meadow fescue with slurry may reduce this advantage. The study was supported in part by USDA-ARS specific cooperative agreement 58-3655-4-052.