The Effects Of Roughage Particle Size In TMR On Chewing Activity And Rumen Fermentation Of Dry Cows

The objective of this experiment was to get DM, NDF and ADF rumen degradability data of several roughages via nylon bag technique and to evaluate effects of reducing forage particle size on dry cows based on measurements of the Perm State Particle Seperator (PSPS).1. The DM, NDF and ADF rumen degradability of several roughages were evaluated via nylon bag technique. The three indices' degradability data were all higher on legume grass than on gramineous grass. Pelleting would increase the rumen degradeability.2. Three cannulated, multiparous dry cows averaging 700±50kg were assigned to one of 3x3 Latin Squares. During each of the 21-d periods, animals were offered one of three diets, which were chemically identical but included alfalfa hay of different particle size which were 2cm, 4cm and 8cm. peNDF was determined by measuring the amount of NDF retained on a 1.18 mm screen. Reducing particle size increased DMI linearly (12.61, 11.65 and 9.41 respectively) and decreased rumen pH and A:P ratio, but total VFA was not different among three treatments. Total eating and chewing activity decreased with reducing particle size. It was concluded from the results above that inappropriate forage chopped length would have detrimental effects on dry cows.