This article is about bark and bite in working dogs, it also has 2 summaries on topics that have been covered in past working dog behavior articles (Force and Temperament)
Bark:

Farm dog Border collie mix
Bark is useful at times, however, it should be used like eye - only when it is necessary to do so amd therefore is not be overused. Mostly barking is greatly overrated. It often causes more harm than good when used by people who always try to rush stock, but only take longer as a result. Maje haste slowly. Often by keeping quiet, and allowing stock room to flow, everything happens much more quickly even though at first glance there may be less happening.
However barking is useful in many situations, such as with a dog on the tail of a mob on a road when most of the mob is unaware of the dog’s presence, or at odd times in the yards, or facing stock over a creek. It is preferable to the dog biting. Bark is also useful when working cattle,if it’s used in moderation at the right moments. For example, when blocking or turning a mob of running cattle the lead or shoulder animals may see the dog but those behind them cab be unaware of it’s presence, the bark can be used well if it is timed and not overused, for instance a few well timed barks can alert the entire mob to the dog’s position and therefore plus effectively stop or turn it, as can a couple of welltimed cracks of the whip.
The problem with most barking dogs is that the bark is a result of (or associated with) an excitable or ratty temperament, or weakness.Most would say give me a calm, silent, strong dog over a weak, excitable, barking dog anytime,but the calm, strong dog is better if it will bark when

Australian Shepard is an original american farm dog.
required. So if your trying to breed some bark into your dogs, always try to breed from calm, strong dogs that bark sensibly with purpose, as they force, not the type that stands back and barks, or yaps aimlessly or out of weakness.
Bite:
As far as bite is concerned a dog should only ever snap at the nose (if sheep of or cattle attack) or the heel of sheep or cattle, and should never hang on. It should do so calmly and fearlessly, and not rush in due to weakness. A dog that bites, and particularly one that hangs on, cannot hold while it forces, and so will never be a good forcing dog.
Force Summary:
The way a dog forces is one of the most important aspects of a high - calibre, practical working dog. No matter how good a dog may be in other area’s, if it lacks force it is of very limited value. Real force comes from a combination of outright strength and the desire to force, which can include some purposeful bark and controlled bite. But for the most part it is simply a steady,

Border Collie working dog.
strong, good covering, free moving closer to stock without hesitation,and meeting any challenges. Mob cover, short cover, drive, and balance are vital components of high quality, exceptional forcing ability,so that the dog holds while it forces, and forces in the right place.
A dog with good force and with distance will only force when required, and will then back off and take stock quietly. A dog that is always putting pressure on stock is nothing but a nuisance.
Temperament Summary:
Temperament is at the heart of every sheep dog’s ability. It determines whether the dog has minimal activity and steadiness, or whether it is busy and excitable. It determines whether it is strong, or weak. It determines whether it is calm and will think about what it is doing to rush into things. It affects whether it uses too much eye when that is not needed.
Also it detrmines how eaasy the dog will be to control. A calm, steady dog with minimal activity will be easier to control, even though it should be hard and strong. If you want to breed dogs that are controllable you should breed calm dogs with great heart , not soft or half heartened ones.
A dogs tail is a good indicator of it’s temperament. If it’s tail is flying around then it is fizzy. If it’s tail comes up when it is walking in or holding then it is tense or weak. The dogs tail should hang down relaxed at all times.
Temperament and work are inseparable. You cannot have a good dog without a good temperament.