Not the most efficient solution (ideally you'd pull out all the hostnames, from all the lines then remove duplicates) but you can do this:

#!/bin/sh
while read line
do
  for hostname in `echo $line | cut -d '=' -f 2 | sed 's/:/ /g'`
  do
    if ! ping -s $hostname 1 1 > /dev/null
    then
      /bin/true
    else
      echo "host $hostname not pingable"
    fi
  done
done