The effect of Feed Bunk Space and Dietary Energy Density on Feeding Behavior and Dry Matter Consumption Pattern in Holstein Heifers

Forty Holstein heifers with an average age of 12-16 months (363.4 ± 32.8 kg BW) were used in a 2×2 factorial design, in which 10 heifers were allocated to four stalls. The current experiment prolonged 100 days with 10 days for adaptation period and 90 days for sampling period. The rations in this experiment had the same forage/concentrate ratio and the only difference was in the amount of dietary energy density and feed bunk space. Treatments included: 1) Small feed bunk space (24 cm) with low level of energy, 2) Small feed bunk space (24 cm) with high level of energy, 3) Large feed bunk space (48 cm) with low level of energy and 4) Large feed bunk space (48 cm)  with high level of energy. The results showed that meal frequency was affected by diet energy density as mentioned parameter was higher for treatments with low energy density in comparison with high energy density. Also, feed bunk space had significant effect on heifer feeding behavior through motivating of competition for feeding. As, the meal frequency (#/day) was higher and meal size (kg/meal) was lower for small feed bunk space in comparision with the large feed bunk space. The results clearly showed that feed bunk space is the key factor to motivate competition behavior of feeding in heifres.