In file Animals.pm, I have

package Cow;
sub Cow::speak {
    my $class = shift;
    print "$class Cow goes moooo!\n";
}

package Horse;
sub Horse::speak {
    my $class = shift;
    print "$class Horse goes neigh!\n";
}

package Sheep;
sub Sheep::speak {
    my $class = shift;
    print "$class Sheep goes baaaah!\n";
}

1;


##</code><code>##


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 ??