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 cannulas were used in a 4 x 4 Latin square design experiment to determine the effects of whole crop barley, oat, and triticale silages substituted for alfalfa silage in the forage portion of diets on chewing behavior and the relationships between attributes of reticular contractions and voluntary intake and digesta passage from the reticulorumen. Mean ad libitum DMI was 18.3 kg/d and was affected by diet. Duodenal flows of DM, NDF, and OM were not affected by diet. The frequency and duration of reticular contractions during eating, rumination, and resting were not influenced by diet. Amplitude of reticular contractions during eating was lower for cows fed alfalfa than for those fed barley silage. The NDF of alfalfa was transferred less efficiently than that of cereal silages at the duodenum. Cows fed alfalfa and barley silage diets transferred less NDF per unit of duration than cows fed oat and triticale silage diets. However, an equal amount of NDF was transferred per unit of amplitude of contraction, regardless of diet. Changes in DMI and digesta passage could be explained only partially by changes in chewing activity and attributes of reticular contractions required to transfer each unit of digesta from the reticulorumen.