EFFECTS OF CEREAL GRAIN SILAGES VERSUS ALFALFA SILAGE ON CHEWING ACTIVITY AND RETICULAR MOTILITY IN EARLY LACTATION COWS

Four early lactation Holstein cows fitted with ruminal and duodenal ca nnulas were used in a 4 x 4 Latin square design experiment to determin e the effects of whole crop barley, oat, and triticale silages substit uted for alfalfa silage in the forage portion of diets on chewing beha vior and the relationships between attributes of reticular contraction s and voluntary intake and digesta passage from the reticulorumen. Mea n ad libitum DMI was 18.3 kg/d and was affected by diet. Duodenal flow s of DM, NDF, and OM were not affected by diet. The frequency and dura tion of reticular contractions during eating, rumination, and resting were not influenced by diet. Amplitude of reticular contractions durin g eating was lower for cows fed alfalfa than for those fed barley sila ge. The NDF of alfalfa was transferred less efficiently than that of c ereal silages at the duodenum. Cows fed alfalfa and barley silage diet s transferred less NDF per unit of duration than cows fed oat and trit icale silage diets. However, an equal amount of NDF was transferred pe r unit of amplitude of contraction, regardless of diet. Changes in DMI and digesta passage could be explained only partially by changes in c hewing activity and attributes of reticular contractions required to t ransfer each unit of digesta from the reticulorumen.