Effect of particle size of lucerne hay on chewing activity, digestion and energy balance of Chinese Holstein heifers

Three 8-month-old Chinese Holstein heifers weighing 300 ± 22.4 kg were selected for a 3 × 3 Latin square design to study the effects of chopped length of lucerne hay (2, 4 cm, and natural length) on chewing activity and feed utilization effi ciency.Results showed that increasing the chopped length of lucerne hay increased eating bout, time spent for eating hay, concentrate and ration, ruminating and total chewing activity.Digestibility was unaffected by the treatments.Decreasing chopped length of lucerne hay decreased heat production and increased energy retained in body.