Bleach is very toxic, especially modern bleach, which contains sodium hypochlorite, much more toxic than chlorine. In addition, the byproducts of its degredation are also very toxic, and can remain in the environment. When used for sanitizing the surfaces must be rinsed with water to wash away any remaining toxic substances. Because of the tremendous amount of organic debris it would have questionable effectiveness in the soil, even against Parvo - Parvo organisms are shed at such a tremendously high number and spread so readily on shoes, clothing and by other means that you would have to saturate the soil to several inches deep and over entire yards before you would have any reduction in virus numbers.
Your best bet with livestock and internal parasites is to use rotational grazing, moving them from pen to pen and leaving one empty for several months at a time, after cleaning as much manure out of it and raking it to expose eggs to sunlight. Along with that have regular fecal exams done to see if your deworming program is effective.
