For comparison: An adult elephant weights about 4500kg to 6000kg. It can lift about 300kg and carry up to 500kg.
Now you want to ask if a creature like a cow (female adult cow weights about 720kg) can throw something which has about triple of its own weight for 6 meters? I mean...come on.
The only creatures able to carry so heavy things compared to their own weight are ants (can carry things 10-50 times heavier than their own weight). And you can't simply scale an ant to human-size or even larger.
Another point of view: Let's assume you build a creature just containing muscles. A muscle can give an energy output of about $30J/kg$. You want to lift $1800kg$ for about $1m$ at a gravitational acceleration of $9.81m/s^2$ or about $10m/s^2$. This will require an energy of $E = m*g*h = 1800*1*10 = 18000J$. This would require a pure mass of muscles of about $18000/30 = 600kg$. So in order to lift this mass 1m over ground, you need $600kg$ of pure muscle!
You don't have taken into account the weight of other important 'parts' like: skeleton, important organs, blood and other fluids, etc.
Further, this $30J/kg$ are optimal conditions for a single contraction of such a muscle-creature! You may be able to lift it, but certainly not throw it anywhere. You also would need to think how a creature would be able to store and access this amount of energy if it really wants to throw something.
Source of the $30J/kg$: Equine Locomotion - E-Book
By Willem Back, Hilary M. Clayton found in google-books, p.18.
Edit: This book gives more valuable information like the peak force various muscles can achieve, etc. If you seriously want to calculate such examples, there are all equations needed.