Short suckling bout duration could be taken as an indicator of shortage of milk and lack of maternal care, and could therefore be used to test the parent-offspring conflict hypothesis. We examined suckling bout duration of 20 plains zebra foals, at the Dvůr Králové Zoo, and collected data on suckling events during 19 months of observation. As expected, suckling bout duration decreased with increasing age of the foal. The suckling bouts differed in duration when terminated by the foal, mother or any other adult mare (foal > mother > herdmate). Thus, bouts terminated by the mother should indicate that demands of the foal were not satisfied. Finally, we found that suckling bout duration was shorter in pregnant mothers than in non-pregnant ones, suggesting higher mother-offspring conflict when the mother was pregnant. In conclusion, this study demonstrates the importance of the termination of suckling bouts and the mother’s pregnancy when interpreting suckling bout duration of equids.