Working code:

#!/usr/bin/perl

use lib '/home/perldood/Custom/perl/lib/perl5/Animals';
use Animals;

Cow->speak;
Horse->speak;
Sheep->speak;

Non working code:

#!/usr/bin/perl

use lib '/home/perldood/Custom/perl/lib/perl5/Animals';
use Animals;

Cow::speak;
Horse::speak;
Sheep::speak;

Can you please explain, Why ??