Age and the effectiveness of chewing during eating in Holstein cows

Abstract

Six lactating Holstein cows with rumen cannulae were separated into age groups of 3, 4 and >5 years old, to examine the potential effect of age on the effectiveness of chewing during eating. The first 15 boluses swallowed during a meal of high-quality long lucerne hay were collected from the cardia to determine their mean particle size and weight. The mean particle size of the swallowed boluses did not differ between age groups. As the meal progressed, the mean particle size of boluses decreased from 3.1 to 1.9 æm. The weight of the swallowed boluses was also unaffected by age. There did not appear to be any relationship between the weight of the swallowed bolus and the time it was collected or mean particle size. Over the normal productive lifespan of cows in the USA, age does not appear to greatly affect the effectiveness of chewing.