|Akins, Matthew - University Of Wisconsin|
Submitted to: Journal of Dairy Science
Publication Type: Abstract Only
Publication Acceptance Date: 2/26/2019
Publication Date: N/A
Technical Abstract: The production of baled silages is increasingly popular; however, some management considerations and fermentation characteristics are notably different from traditional precision-chopped silages. Our objectives 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 from about 40 to 70%. Thirty-one 1.2 × 1.2-m round bales made from a mixed alfalfa-orchardgrass stand (56.5% alfalfa; 42.7% orchardgrass) were baled with or without engagement of the bale-cutting system over 4 bale-moisture groupings (67.5, 61.5, 51.1, and 45.8%). Bale-cutting improved initial wet bale weights (668 vs. 641 kg; P = 0.003), but only numerical differences (P = 0.144) were observed for initial dry bale weights (287 vs. 278 kg) and initial DM density (192 vs. 188 kg DM/m3). Overall, the effects of initial bale moisture and cutting had little meaningful effect on silage nutritive value, except that silage fermentation reduced concentrations of neutral-detergent insoluble CP (% of CP) compared to pre-ensiled forage by 48 to 68%. Following fermentation, modest improvements were noted within cut bales for lactic acid, percentages of total VFA comprised of lactic acid, and a more acidic final silage pH. Final silage pH was best related to initial bale moisture with simple linear models for both cut (Y = - 0.031 x + 7.50; R2 = 0.847) and uncut (Y = - 0.033 x + 7.74; R2 = 0.869) silages. Tests of homogeneity indicated that slopes did not differ (P = 0.653) on the basis of bale-cutting engagement, but intercepts were different (P = 0.024). For the silages in this study, the cumulative effects of improved fermentation within cut forages represented pH declines of about 0.10 to 0.16 pH units over initial bale moistures ranging from about 40 to 70%. Although there may be practical or logistical reasons for bale cutting, such as easing incorporation into TMR rations, improvements in silage fermentation observed in this study were very modest, and do not really justify engagement of cutting systems solely for that specific purpose.