If you're using SNMP.pm, there's already a method for doing this:

From the cpan documentation:

get_table() - retrieve a table from the remote agent  

Blocking 

   $response = $session->get_table($oid);


Non-blocking 

         $ok = $session->get_table(
                            -baseoid   => $oid,
                            [-callback => sub {},]
                            [-delay    => $seconds]
                         );
[download]

it might be best to use a module here rather than depending on system commands and/ or backticks.

i do a fair to large amount of SNMP work at work, and I use SNMP.pm for most, if not all, apps that need this kind of info.