My primary language is English. Shakahari is a word in Sanskrit, a language which I do not speak very much of, however I know a few words in Sanskrit as they pertain to Hinduism, and Raja Yoga. Having warned you that my definition as to what shakahara means is not an expert definition, let me go on to say that my understanding is that it means plant-eating - shaka meaning plant, hara meaning eating. You can practice shakahara for any reason. Practioners of raja yoga may practice shakahara as part of their practice of Ahimsa. Himsa meaning harming, and a meaning not. Ahimsa is being careful so as to avoid causing harm. Ahimsa is practicing being mentally alert to what one is doing, so as to not to cause injury or fear. Ahimsa is maintaining vigilance. It is guarding of one's actions. The idea is that since animals can feel injury and fear much the way humans can, working to avoid causing injury to them or fear, provides good practice for us, for the task of avoiding causing injury to humans.
You could envision the purpose of a yoga practitioner in practicing shakahara as not so much to provide for the well-being of animals, but to practice doing for them, what it is important for us as humans to do for other humans. This is not to say we don't care about the animals or are only pretending to care. It is just saying that providing for the well-being of the animals is not our main goal. When possible, we should allow animals to take care of themselves, rather than be over-protective, rather than treating adult animals as one would treat children. Adult humans do not benefit from it when we do this, and neither do animals. It weakens them. Weakening an animal or person and making it difficult for them to take care of themselve, is not being kind to them, even though one may have the illusion that one is being caring and kind when doing so. It can be harmful to them. It can himsa. This is not to say that one should never intervene in behalf of animals. I am thinking of interventions such as habitat protection.
Practitioners of Raja yoga practice shakahara, as an exercise that provides them with practice in not causing injury, with the goal of making vigilance about avoiding causing injury become second nature to us.
As ahimsa becomes more and more second nature, eventually it becomes possible for light to find us.
The purpose of yoga is to make it easier for the light to find you. If successful you become illuminated by the light. The light may find you; however you cannot find the light. That is how one experiences it. Seeking illumination does not result in illumination. Saying you are seeking illumination is like saying you are looking for your eyes. You are the light, so there is nothing to seek. However you can make yourself such that it is easier for your light be experienced.
Where does the light come from? Does it come from without? Does it come from within? The answer is that the distinction between in and out is a false distinction. The distinction may be an useful abstraction. To dispense with this abstraction completely may not be very practical. But at a basic level, the distinction between person and environment is false. The idea that there are objects (1) outside you, that you know about when (2) your sense organs inside you are energized by them, is not true. There is no distinction between outside thing and the inside sense of the thing, there is only one thing. And you are it. This is not to say that there is only inside things, and no outside things. And it is not to say that there are only outside things, and no inside things only sensations of them. What it is saying is that the thing and its sensation are one thing. What it it is saying is that not only do you alone exist, but you encompass a great deal more than what is commonly imagined, and what you may imagine, to be the borders of self. All kinds of things that are beyond your control, are not merely things in your environment, but are part of you.
Yoga is the art of linking these things, yoking them together, in your understanding. The kind of poise you can acquire by doing this can be useful.