Influence of hay particle size at different concentrate and feeding levelson digestive processes and feed intake in ruminants

In order to study the main effects of particle size three ruminally fistula ted cows were fed a hay rich in fibre in long (28.7 mm), chopped (9.2 mm) a nd ground (2.9 mm) form in a 3 x 3 Latin square design. In another three fa ctorial experiment with 8 wethers (4 animals were ruminally fistulated) the main effects and interactions of the above mentioned hay particle size at two concentrate levels (10.4 to 13.3 and 29.5 to 40.1% in the ration) and a t two feeding levels (restricted and ad libitum) were investigated. There w as no effect of chopped hay (9.2 mm) on chewing activity, whereas ground ha y (2.9 mm) reduced rumination time (52% in sheep and 36% in dairy cows) and chewing expense (time unit of DM or NDF intake). These effects were more p ronounced at high concentrate intake. Sheep increased feed intake more thro ugh reduction of rumination expense than through the extension of ruminatio n time, pH-value, concentration of bicarbonate and C2 : C3-ratio indicate f avourable fermentation conditions in long (28.7 mm) and chopped hay (9.2 mm ), whereas a negative influence of ground hay (2.9 mm) or ruminal fermentat ion could be observed.