Nutritive value and fermentation characteristics of round-baled alfalfa–orchardgrass forages ensiled at various moisture concentrations with or without baler cutting engagement

Abstract

Objective: The objectives of this research were to compare the silage fermentation characteristics and nutritive value of cut and uncut alfalfa (Medicago sativa L.)–orchardgrass (Dactylis glomerata L.) baled silages packaged at moisture concentrations ranging between 40 and 70%. Materials and Methods: Thirty-one 1.2 × 1.2 m round bales made from an alfalfa–orchardgrass stand (56.5% alfalfa; 42.7% orchardgrass) were baled either cut or uncut over 4 bale groupings (67.5, 61.5, 51.1, and 45.8% moisture). The cutting mechanism within the baler was configured with 15 knives spaced at ~7.5 cm. The experimental design was a randomized complete block with 4 replications (field blocks); we evaluated a 4 moisture groupings × 2 particle lengths (cut or uncut) factorial arrangement of treatments. Results and Discussion: Cutter engagement increased initial wet bale weights (668 vs. 641 kg; P = 0.003) but had no effect on nutritive value (P ≥ 0.104). Final silage pH was best related to initial bale moisture with a linear regression model for both cut (Y = −0.031x + 7.50; R2 = 0.847) and uncut (Y = −0.033x + 7.74; R2 = 0.869) silages. The cumulative effects of improved fermentation for cut forages represented pH declines of about 0.10 to 0.16 pH units over initial bale moistures ranging from 40 to 70%. Implications and Applications: Bale moisture had a greater effect on fermentation than the use of bale-cutting systems. The modest fermentation improvements observed in cut bales suggest only limited potential for improved silage fermentation on that basis.