EFFECT OF SPACE ALLOWANCE, ACCESS TO BEDDING, AND FLOCK SIZE IN SLATTED FLOOR SYSTEMS ON THE PRODUCTION AND HEALTH OF DAIRY HEIFERS

An experiment was conducted on seven Danish commercial dairy farms wit h 200 Danish Friesian heifers (315 kg) in 152 days from the month of N ovember. Founded on existing slatted floor systems, 32 experimental pe ns were established with Low (L) or High (H) space allowance (1.5 vs. 3.0 m(2) per animal), different type of separate lying area (Slatted ( S) vs. Bedded (B) floor) and different flock size (6 vs. 12 animals). Eating spaces were standardized to about 50 cm per animal. Ad libitum feeding was practised and rations contained a maximum 30% concentrates (dry matter). An increase in space allowance from 1.5 to 3.0 m(2) per animal in pens with fully slatted floors increased the live weight ga in by 174 g day(-1) or 31% (P = .04) and net energy intake per kg live weight gain was reduced by 23% (P = .04). Heifers housed in small pen s lay down less than heifers in large pens. Access to bedding affected number of lying periods. Production, however, was not influenced by a ccess to a bedded lying area. Flock size is of minor importance for he ifers' production, when fed ad libitum and one eating space per animal is ensured. The prevalence of heel horn erosion was reduced and claw length was increased in heifers with access to bedding. No occurrence of tail tip necrosis regardless of pen type was found. Reproduction ex pressed as ages at pregnancy was not significantly influenced by any o f the treatments.