Hungry and barking!

Question
Hi there,
I have a two year old male cocker who has suddenly become obsessed with food.  We feed him a kangaroo tail bone in the morning when we leave for work and 2 cups of food in the afternoon/evening (1.5 cups for dinner and .5 cup before bed).  He gets moderate exercise and sleeps most of the day.  He hasn't put on or lost weight, but he is 'hounding' (pardon the pun) us for food by whining.
I have been told that he barks and howls for a while after he's finished his bone in the morning after we have left.  I know that cockers are social dogs, but we have to be able to leave him every now and then.  We give him a bone to distract him as we leave and I'm beginning to think it's not the right thing to do.  He finishes it and then crashes at the door and barks.  He also barks at seemingly nothing (though his attention seems to be focussed on 'something' we can't see) in the backyard.  We have checked for other animals, lizards, toads, snakes etc. but we can't find what it is and he doesn't stop if we don't tell him to stop.  If we're not there, he continues for up to half an hour.  I'm concerned he will overly upset our neighbours.
I have considered a bark collar, however, I do love how vocal he is (not the barking, but using his voice in other ways).  Will using a bark collar be effective?  Also, if we use a bark collar, will it deter him from 'talking' to us when he is happy?  I know this sounds silly, but he has such a personality and I'd hate to lose that because I couldn't manage his barking issue.
Thank you.

Answer
How often and for how long is he walked daily?  How long is he left alone?

Please begin giving him a proper breakfast.  It's not enough and he's letting you know :).

I don't recommend a bark collar and feel this is a training issue.

Boredom and a lack of exercise is usually the reason for this type of behavior.