How to remove 'additional section' from DNS reply in RHEL6

Issue

There are 2 RHEL servers (RHEL5 and RHEL6) having DNS serving several zones as forward zones to some other DNS:

 # cat /etc/named.conf
...
zone "example.ru" IN {
        type forward;
        forward only;
        forwarders { <other DNS ip>; };
};

zone "example1.ru" IN {
        type forward;
        forward only;
        forwarders { <other DNS ip>; };
};

The problem is that during DNS query RHEL6 host returns additional section that contains list of authoritative nameservers for zone (ru given as example):

[root@rhel6]# dig MX example.ru @localhost

; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.17.rc1.el6_4.6 <<>> MX kmz-tula.ru @localhost
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 17052
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 10

;; QUESTION SECTION:
;example.ru.                   IN      MX

;; ANSWER SECTION:
example.ru.            3600    IN      MX      10 mail.example.ru.

;; AUTHORITY SECTION:
ru.                     172799  IN      NS      f.dns.ripn.net.
ru.                     172799  IN      NS      a.dns.ripn.net.
ru.                     172799  IN      NS      b.dns.ripn.net.
ru.                     172799  IN      NS      e.dns.ripn.net.
ru.                     172799  IN      NS      d.dns.ripn.net.

;; ADDITIONAL SECTION:
a.dns.ripn.net.         172799  IN      A       193.232.128.6
a.dns.ripn.net.         172799  IN      AAAA    2001:678:17:0:193:232:128:6
b.dns.ripn.net.         172799  IN      A       194.85.252.62
b.dns.ripn.net.         172799  IN      AAAA    2001:678:16:0:194:85:252:62
d.dns.ripn.net.         172799  IN      A       194.190.124.17
d.dns.ripn.net.         172799  IN      AAAA    2001:678:18:0:194:190:124:17
e.dns.ripn.net.         172799  IN      A       193.232.142.17
e.dns.ripn.net.         172799  IN      AAAA    2001:678:15:0:193:232:142:17
f.dns.ripn.net.         172799  IN      A       193.232.156.17
f.dns.ripn.net.         172799  IN      AAAA    2001:678:14:0:193:232:156:17

;; Query time: 46 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Wed Feb  5 13:06:13 2014
;; MSG SIZE  rcvd: 372

This is a change from RHEL5 which doesn't have 'additional section':

[root@rhel5]# dig MX example.ru @localhost

; <<>> DiG 9.3.6-P1-RedHat-9.3.6-20.P1.el5_8.6 <<>> MX kmz-tula.ru @localhost
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 12715
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 3

;; QUESTION SECTION:
;example.ru.                   IN      MX

;; ANSWER SECTION:
example.ru.            3554    IN      MX      10 mail.kmz-tula.ru.

;; AUTHORITY SECTION:
example.ru.            3594    IN      NS      ns1.example.ru.
example.ru.            3594    IN      NS      ns2.example.ru.

;; ADDITIONAL SECTION:
mail.example.ru. 1154 IN     A       XXX.XXX.XXX.XXX
ns1.example.ru.   3594    IN      A       XXX.XXX.XXX.XXX
ns2.example.ru. 3594 IN    A       XXX.XXX.XXX.XXX

;; Query time: 0 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Jan 30 10:04:08 2014
;; MSG SIZE  rcvd: 161

Is it possible to remove this 'additional section' from reply for particular zone or in general?