Guard dogs should be fed and then the food bowl removed before chickens can consume the dog's food. Running pigs and chickens together can lead to disaster. Pigs will run down and kill chickens.
I agree. I've heard of plenty of problems developing between guard dogs and the animals they're guarding due to human mismanagement, generally involving feeding malpractices, or using poorly bred animals, or trying to cut too many corners, never mind trying to use just any type of dog for a specific and specialized purpose.
All pigs I've ever known ended up being kept separate from all other livestock, no matter what species or size, precisely because they did display predatory, carnivorous behavior, among other issues.
Re: all those comments about using crossbreeds... This doesn't work for most people. Most mixed breed dogs, or cheap Maremmas or Heelers, are cheap precisely because they're not fit for just about any purpose. I've known a positive glut of crap worker-breeds and mixes from the wrong background or the wrong breeding plan that were unfit for anything more than being lawn ornaments.
Australia is chock-full of useless Heeler/Maremma/Kelpie/Collie and similar mixes which are at best a danger to everything around them. You generally get what you pay for. Crosses are best known for being some of the most pointless animals in existence when it comes to working dogs. You get maybe one good one for a thousand useless ones that are only able to be pets and cause harm when used in any other situation. Heck, most of them don't even make good pets either. All that working drive but not enough intelligence, or too much disobedience.
I like Dingoes, I find them great dogs, but it doesn't mean I'm so short sighted I'd recommend my personal preference as being the ideal working dog for all situations just because it works for me. lol... Same is true of many working dog mixes. Leave designer breeds to puppy mills and people who only want ornamentals.
I'm not sure where the notion of 'high breeding' came into it, since good breeding is just that, no fancy terminology required.
For most uses, if you want a reliable working dog, don't go getting it from a backyard pet breeder, lol! And don't go buying a suspiciously cheap one either. Unless you're willing to gamble on that risk and the potential consequences.
Best wishes.