Antelope have true horns on their heads, versus antlers. We have all seen nontypical antlers, but the horns are formed differently. He may have a genetic defect or damage to the (and I want to say) cuticle where the horn emerges.
I'd be asking the fish cops for a trophy antelope depredation tag that was good for your land location. Those buggers look like they ate all the crop off down the stubble and are still hungry. If you get even one, they'll get the message and go swarm someone else's field.