Competition for teats and feeding behavior by group-housed dairy calves

Many farms using teat-based systems for supplying milk for calves provide only one or a small number of teats for a group of calves, but no previous research has addressed how competition for teats affects calf behavior or milk intake. The aim of this study was to determine how restricted access to teats affects calf competitive behavior, meal-based feeding patterns, and milk intake. Female calves (n=15) were divided into 5 groups of 3 calves each and fed with a teat-to-calf ratio that varied daily from 1:3 to 4:3 using a switchback design. Feeding behavior was recorded by scoring the time and duration of each sucking event. We defined meals using the frequency distribution of log intervals between visits to the teat and identified the within-meal and between-meal distributions intersection points. Three classes of intervals were identified based on the intersection points of the distributions: 1) intervals <2 min, representing small breaks away from the teat within a meal; 2) intervals >41 min, providing an objective definition of a new meal; and 3) an intermediate distribution of intervals from 2 to 41 min could be included in either of the other 2 classes. Meal number showed no significant decrease with decreasing teat number. However, total time on the teat decreased from 40.2 to 32.7 (+/-2.6) min/d, and milk consumption declined from 14.0 to 11.4 (+/-0.8) L/d as teat number declined from 4 to 1. In addition, competitive interactions became more frequent when teat access was reduced; the number of times calves displaced one another from a teat increased from 18 to 41 (+/-5) times/d when teat number decreased from 4 to 1. In conclusion, reduced access to teats increases competitive interactions, decreases feeding time and decreases milk intake by group-housed calves.