Competition for feed affects the feeding behavior of growing dairy heifers.

The objective of this study was to determine how competition for feed influences the feeding behavior of young, growing dairy heifers. Thirty-six prepubertal Holstein heifers (231.5 +/- 12.1 d old, weighing 234.7 +/- 24.0 kg), consuming a total mixed ration ad libitum, were assigned to 1 of 2 treatments: noncompetitive (1 heifer/feed bin), or competitive (2 heifers/feed bin). After 7 d of treatment adaptation, dry matter intake and feeding behavior were monitored for 7 d for each animal. Fresh feed and orts were sampled on the last 3 d of the treatment period from each bin and were subjected to particle size analysis. The particle size separator consisted of 3 screens (18, 9, and 1.18 mm) and a bottom pan resulting in 4 fractions (long, medium, short, and fine). Sorting activity for each fraction was calculated as the actual intake expressed as a percentage of the predicted intake. There was no difference in sorting behavior or dry matter intake between the treatments. Overall, the heifers sorted against long particles (94%), and sorted for medium (102%) and short (103%) particles. The competitively fed heifers tended to have 10% shorter feeding times, particularly at peak feeding periods. The competitively fed heifers also consumed 9% fewer meals per day, although the duration of these meals were 10% longer, and tended to be 13% larger. Competition for feed also tended to increase the day-to-day variation in feeding time, meal duration, and meal size. It can be concluded that competition for feed for growing dairy heifers alters feeding patterns, reduces access to feed, particularly during periods of peak feeding activity, and tends to increase day-to-day variation in feeding behavior.