How dairy heifers initially respond to freestalls: The effect of neck-rail placement.

Dairy heifers are often kept on open packs early in life and later transitioned to freestalls. The neck rail in freestalls acts as a barrier intended to prevent animals from entering too far in the stall, with the aim of improving stall cleanliness. Unfortunately, this barrier can hinder stall use and may be a hazard to animals due to physical contact, perhaps especially when animals first learn to use the stall. The primary aim of this study was to investigate the effects of 2 different neck-rail positions on frequency of stall use (for lying and standing) and misuse (standing or lying backward in the stall and lying down outside of the stall) by dairy heifers when first introduced to freestall housing. A secondary aim was to measure, via the use of an instrumented neck rail, the maximum force (N) with which heifers contacted this part of the stall. Holstein heifers (n = 8 per treatment) were randomly assigned to one of 2 neck-rail positions: 110 and 130 cm (as measured diagonally from the inside of the rear curb to the bottom of the instrumented neck rail, 0.7 m above the bedded stall surface). Animals were tested individually and responses were measured for 6 h following introduction to the freestalls. On average (median, minimum, maximum), heifers lay down 3.5 (0, 6) times in the freestall when the neck rail was positioned at 130 cm versus 0 (0, 4) times at 110 cm. Heifers also were more likely to stand fully in the stall when the neck rail was positioned at 130 cm versus 110 cm (3.5, 0, 9 vs. 1, 0, 3), and were also more likely to stand backward in the stall (3, 0, 5 vs. 0, 0, 1). In contrast, heifers tested at the 130 cm position were rarely observed lying down outside of the stall (1, 0, 4), whereas this behavior was more common at the 110 cm treatment (4, 0, 7). Contrary to our expectation, the force with which heifers contacted the neck rail was higher in the 130 cm versus 110 cm treatment (337, 6, 548 vs. 78, 26, 403 N). We conclude that neck-rail position acts as a barrier for naïve heifers, such that a more restrictive position reduces the likelihood that heifers use the stall correctly.