When you add the time 23:59:59 to the end DateTime object something like the following then the end date will be included in the period:
<?php
$date_start = new DateTime('2012-03-12');
$date_end = new DateTime('2012-03-22 23:59:59');
$interval = '+2 days';
$date_interval = DateInterval::createFromDateString($interval);
$period = new DatePeriod($date_start, $date_interval, $date_end, DatePeriod::EXCLUDE_START_DATE);
foreach($period as $dt) {
echo $dt->format('d/m');
}
?>
OUTPUT:
14/03
16/03
18/03
20/03
22/03