First of all, dominance theory is a well-busted myth. Dogs do not have linear hierarchies, and are not trying to "rule the roost." Behaviors like this are from a lack of training and communication, not because the dog is trying to aggressively dominate you or your mother.
Here is the Association of Pet Dog Trainers stance on dominance theory: http://www.apdt.com/about/ps/dominance.aspx
An article on "Dog Whisperer Psychology;" basically an article on the sudden popularity in the media of dominance-themed training theory and why it is incorrect, also has a ton of good links at the bottom: http://www.4pawsu.com/dogpsychology.htm
James O'Heare discussing "What's Wrong with Dominance" in an interview: http://www.associationofanimalbehaviorprofessionals.com/whats_wrong_with_dominance.html
Now that that is covered, I want to cover another thing before I give advice, and that is correcting dogs for showing aggression. Despite my dislike of punishments altogether, I really must ask you please do not punish a dog for showing an aggressive response, and I will explain to you why.
Aggression is a form of communication for dogs, whether it's a hard stare, freezing, growling, snarling, snapping, inhibited biting, or biting that draws blood, aggression is communication. Dogs can not verbally say "I do not want to get in the truck." So they have to resort to their body language to tell you, and in this case, it was aggression. Aggression is a way for dogs to say "I do not like this/what you are doing," "I am not comfortable with this situation, please stop," or "Do that thing I don't like again and I'll show you I mean it." So, as much as aggression may not be appropriate in these situations, please at least respect that your dog is openly trying to tell you something.
So, for one thing, we do want our dogs to communicate with us. So punishing them for aggression is punishing them for communicating. How are we to know if they feel uncomfortable, scared, angry, upset, etc., if we take away their ways of telling us? Dogs display aggression for various reasons, and it's a very rare dog that randomly aggresses. So, we have to assume your dog is behaving aggressively for a reason. He's scared, in pain, uncomfortable, or unsure about a situation, or he just strongly dislikes it. Punishing a dog for expressing his discomfort will do absolutely nothing in getting him to feel comfortable about it. It does NOTHING to address his actual feelings (of dislike, distrust, fear, etc.) towards the stimulus causing the aggression, and could potentially cause an even greater dislike, because it is now associated with punishment. Rehabilitating dogs displaying aggressive behaviors should really be about making the dog feel comfortable in a situation or around a stimulus that before caused an aggressive response.
To compound the issue, punishing a dog for aggression can cause dogs to "bite out of nowhere." You are taking away his ways of communicating every time you correct him for growling, snarling, hard stares, freezing, or snapping. Growling and snapping is often a way of saying "keep doing that and I will bite," so suppressing growling behavior (and other behaviors that happen prior to a dog biting) takes away all your warnings. So, you are taking away his ways to communicate, and doing nothing to make him feel comfortable in these situations, so he still feels uncomfortable/scared/unhappy/etc., and is still just as likely to bite as he was before. Often times I see dogs that bite out of nowhere are dogs that have previously been punished for growling (or similar behaviors) - they simply no longer use growling as a warning sign.
So any training or "rehab" your dog should have, should be focused around showing him the situations/stimuli causing an aggressive response are not scary, not uncomfortable, not pain-inducing, and are something to be looked forward to and liked. So, if he bites when people pick him up, you should focus training on getting him to view being picked up as a positive experience.
So, my advice would be lose the training collars, forget about them. Any sort of correction based training will NOT, in the long run, help you with his behavior. It may initially suppress ALL of his behavior, but it will do nothing to fix the root cause of the problem - the fact he dislikes whatever is causing him to behave aggressively.
Now, my advice is get him to the vet to get a full check up. Get blood drawn, his thyroid checked, etc., and make sure his sudden aggressive response is not caused by a medical issue.
Secondly, all medical tests showing nothing wrong, I'd get the help a behaviorist or dog-training professional who is experienced in dealing with aggressive dogs via positive methods, and that can help you get to the root of the problem, and help you re-train and re-socialize your dog. It sounds possible that he was not properly socialized and trained from the get-go, and is expressing his distrust/dislike/discomfort/confusion via aggressive behaviors. If you do NOT tackle this properly now (with an experienced positive-based trainer who is not going to punish your dog for growling), it will get worse.
I would re-start your relationship with your dog. It sounds like he doesn't trust you or your family (which is easy to do with Cattle Dogs!), and needs some confidence and trust building exercises via low-pressure punishment-free training.