Following weaning, the series of housing that dairy heifers experience is one of the greatest challenges that they face in route to joining the milk herd. At Miner Institute, heifers will shift from having resting space provided in a hutch, to a bedded pack, to free stalls. The last change is the most difficult.
A Norwegian survey of stall refusal found that an average of 6 percent of cows refused to use a free stall, however the range across enrolled farms was from 0 to 55 percent. Similarly, the feeding barrier changes from individual buckets to a post-and-rail barrier to headlocks as heifer transition from the weaning phase of their development to the breeding phase. Successful adaption to each new barrier is a must as there is no alternative means to access feed. Despite the importance of the successful transition from one housing environment to the next, there is little research detailing the behavioral changes that occur during adaption. Understanding these changes is the first step to establishing what changes are the most problematic and developing management practices that will minimize them.
A recent study published in the Journal of Dairy Science from the University of British Columbia investigated the respective changes to resting and feeding behaviors when heifers were introduced to free stalls and headlocks. Secondarily, these researchers quantified the effect that one aspect of stall design, the neck rail, would have on usage when introduced. Free stalls included in the study were 2.6 feet wide (center-to-center) and 5.9 feet long, cleaned once daily, and bedded with clean sawdust weekly. Unrestricted access to fescue grass hay and 5.1 pounds/heifer per day of concentrate was provided initially via a diagonally slanted feeding barrier 9.8 inches wide; the response to free stalls was quantified, then headlocks (13.8 inches wide). The effect of the neck rail was tested by comparing the lying behavior in the presence or absence of a neck rail.
The transition to free stalls lying time per day decreased to 11.3 hours from an average of 14.2 hours/day in the bedded pack. Lying times increased to 13.6 hours/day in the free stall housing. On the day of free stall introduction, heifers spent 2.5 hours lying in the alleyways, a behavior that was not observed in the bedded pack.
Over the course of the experiment, lying in the alley decreased to 1.5 hours. The lost lying time on the day of transition was spent standing, ideally in the feed alley. Feeding time (6 hours/day) was unaffected by the transition to free stall housing. On the other hand, the shift in feed barrier decreased feeding times by 30 min without affecting lying or standing behavior. Feeding time eventually increased to 5.9 hours in the headlocks, which was not different from the diagonally slanted barrier. The presence or absence of the neck rail had little effect on stall usage. Time spent lying in a free stall or standing in the alley was the same with either neck rail scenario. Standing with two feet in the stall was the one aspect of stall usage altered by the neck rail. In its presence, there was a two-fold increase in this behavior.
Overall, the results of these experiments suggest that, in general, heifers readily adapt to the various housing conditions to which they are exposed. However, some individual heifers did quite poorly when introduced in spite of the quick return to the mean time budget established in the original housing conditions. This indicates the importance of closely monitoring heifers when introducing new housing features (free stalls, headlocks, etc.) to ensure that all have sufficient access to resources.