Assessment of feed intake activity lactating dairy cattle fed diets with different particle sizes using new automatic chewing activity recorder

In this experiment for the first time in Iran, designing, manufactureing and use of a new automated chewing activity recorder was evaluated to assay feed intake activity in lactating dairy cattle fed diets with different particle size. 8 Holstein cows are similar production, weight, age, breed and health, were used in a changover design 2×2 with two 21-day periods. The chewing activity that record visually and automatic recorder was not significant different that indicates the accuracy and performance of the new device. During of intake, jaw movements decreased when particle size of alfalfa hay increased. The number of jaw movements per minute when feed intake was not significant between the two treatment (P=0.1302). The jaw movement per a second was reduced when particle size of alfalfa hay increased. The jaw in each opening and closing movement were reduced when dietary forage particle size increased. The number of chewing per second was 1.36 time for ration containing shorter particles alfalfa hay and 1.33 time for larger particles alfalfa hay that were not statistically significant difference (P=0.1491).