It is naturally fermented, unfiltered and most importantly, unpasturised. NRG Vinegar has an acidity rating of 4.5% – 5% – the international standard being 4%. Not all horses will take to the taste immediately, so its recommended to add a small amount until your horse gets used to the taste. There are a few horses that will not accept the added taste. One reason being is that too much Apple Cider Vinegar has been added too quickly to there feed and water, not allowing the horse to get accustomed to the taste.