Effect of Stocking Density on Eating Behavior of Finishing Hanwoo Steers (Bos taurus coreanae)

This study was carried out to investigate the effects of stocking density on eating and ruminating behavior of Hanwoo steers (Bos taurus coreanae) in the finishing period. A total of 30 finishing Hanwoo steers ($631.3{\pm}11.4$ kg, 25 months old) were allocated to one of four stocking density groups comprising 1, 2, 3, and 4 steers per 32 $m^2$ pen [G1 (32 $m^2$), G2 (16 $m^2$), G3 (10.7 $m^2$) and G4 (8 $m^2$), respectively] in triplicate. Eating, rumination behaviors, as well as dry matter intake of steers were measured, and the results were subjected to analysis of variance with stocking density as the main effect. The results of eating behaviors over 48 hours are summarized as follows: Total intake was significantly (p<0.01) higher in G1, G2, and G3 compared to G4. Eating time was not different among the treatments, whereas ruminating time increased in the order of G1 > G2 > G3 > G4 (p<0.01). However, resting time and chewing time (sum of eating and ruminating) were not significantly different among the treatments. Number of boluses and number of total chews were highest in G1 (p<0.01), whereas number of chews per bolus was highest in G3 (p<0.01). Ruminating time per bolus as well as number of boluses per minute was not significantly different among the treatments. Number of defecations was higher in G1 and G2 animals compared to G3 and G4 animals (p<0.01). However, stocking density had no effect on drinking or urination. In conclusion, increasing stocking density (i.e. G4) per pen decreased voluntary intake, ruminating time, and total chewing number in the finishing period of Hanwoo steers. However, care must be taken in discussing stocking density in the present study as the space allowance per animal was satisfactory to meet the current animal welfare regulation in Korea and in Europe, although the beef production system in Korea is more intensive than in Europe.