Effect of space allowance in deep bedding systems on resting behaviour, production, and health of dairy heifers

An experiment was conducted on three Danish commercial dairy farms using 70 Danish Friesian heifers over a period of 141 to 162 days beginning in November. Average body weight of the heifers was 315 kg at the beginning of the experiment. Fourteen experimental pens were established with a flock size of five and different space allowance in the deep bedding area: 1.8, 2.7, and 3.6 m2 resting area per heifer. The total space allowance inclusive of an unstrawed area at the feed manger was 3.6, 4.5, or 5.5 m2 per heifer in herd 1, 3.6 or 4.5 m2 per heifer in herd 3, and 3.0 or 4.9 m2 per heifer in herd 2. Eating space was standardized within pens to 60 cm per animal. Feed was available ad libitum. At 1.8 m2 resting area per heifer, the heifers were unable to synchronize their resting behaviour, and the variance of the daily lying time was higher compared with heifers at 2.7 or 3.6 m2 resting area. None of the heifers were lying on the unstrawed area. Total lying time was not affected by the space allowance of resting area. There was a tendency towards more aggressive interactions at the lowest resting area of 1.8 m2 per heifer. Frequency of abnormal behaviour was very low and was not affected by the space allowance. Daily gain and feed intake were increased in heifers with a resting area of 2.7 or 3.6 m2 compared with 1.8 m2, but the feed conversion ratio was unaffected. The prevalence of heel horn erosion was higher at 1.8 m2 resting area compared with 2.7 and 3.6 m2. For heifers with access to 2.7 or 3.6 m2 compared with 1.8 m2 resting area per heifer both welfare (behaviour and health) and production were improved.