The answer you get of this question may vary if you ask different people. The priest may say, yes it is. But many Balinese, although they are Hindu, consume beef. And people in Bali breed cows for meat. You will not see cow wander in the streets, because they are just cattle.
Some people don't eat beef because they think they should not eat beef because they think it is a sacred animal. They say they will have a headache if they do so. Well, may be because of the cholesterol or some thing like that.
And another thing, we don't consume cow milk or any other milk in the past. We just recently do this, because it is been advertised a lot in the media, that milk is healthy for our body. But many of the older generations, many of our parents or grand parents don't fancy milk. They don't drink milk, they'd rather drink coffee than drinking milk. I can understand that, because milk taste awful sometimes.
Oh, did I mention that our cow doesn't produce any milk? Their milk is only enough for their baby cows, so this is another reason why we don't consume milk.