ARTICLE 94 FEED & ADDITIVE MAGAZINE July 2025 content were adjusted using timothy hay at two chop lengths and some pelleted beet pulp to further reduce uNDF240. Table 2 shows that cows on the high digestibility/low effective fibre treatment had approximately 45 minutes less eating time but consumed over 2.26 kilograms more feed as compared to the low digestible/high effective fibre diet. The animals on the low digestible diet (high uNDF240) with the longer timothy hay spent more time eating to reduce particle size and more time chewing due to the structure of the fibre. When the timothy dry hay was mechanically reduced in particle size, eating time decreased and milk production and DMI improved. There appears to be an intersect between forage quality and particle size with potential for improved milk performance when lower quality forages are chopped finer. This study also demonParticle Size Fine Coarse Fine Coarse TMR (mm) 9.36 10.42 9.19 11.55 Cud (mm) 7.96 7.46 7.51 7.78 Eating Time min/day 255 263 279 300 Eating Time min/kg of DMI 9.09 9.62 10.08 11.86 Chewing Time min/day 523 527 532 545 Milk Kg 47.0 45.7 46.4 44.6 DMI Kg 27.5 27.3 27.6 24.9 Digestibility (uNDF240) High Digestibility (8.5% of DM) uNDF 240 Low Digestibility (11.5% of DM) uNDF240 Mean Particle Size Eating and Rumination Performance Table 2. Particle size reduction during eating and effect on chewing behaviour 2018 Miner Institute Study: Undigested & Physically Effective Fiber Dietary Forage (% of DM) and Eating Behaviour Responses 1000 800 600 400 200 0 40% Forage 50% Forage Eating, min/day Total Rumination, min/day Cud Chewing, min/day Resting Time, min/day 60% Forage 70% Forage Jiang et al., 2017 Figure 1
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