There are number of virus which have animal as reservior and jump to human to cause disease. Why dont we use antibodies of animal to cure humans? Like rabies in bats.
I think you're asking why don't we take antibodies from previously-infected host animals and treat humans with them. In principle, that could work, but it's impractical as you describe it. You give the example of "rabies in bats". Imagine trying to get enough blood from a 25-gram bat to treat a single person. Farming bats is hardly practical, and if you're bleeding wild bats, you're probably collecting both known and unknown viruses that you're then injecting into your patient. So this is completely impractical with wild animals, which are the donors of most of the diseases in question.
However, there's nothing magical about the antibodies from the original wild animal. (This seems to be widely misunderstood, probably from movies that make medically idiotic and impossible claims.) Any antibody can be potentially valuable for treatment, whether it comes from the original host or not, and whether it comes from the live pathogen or from a vaccine made from the pathogen.
So a more practical approach is to infect a large, easily-handled domestic animal with the pathogen in question; or better yet, with a vaccine made from killed pathogens, so there's no risk of the animal getting sick or or infecting your patient. This used to be done with rabies, in fact, using equine hyper-immune serum to treat rabies patients (Production of hyperimmune antirabies serum in horses).
However, there are major problems even with this approach. It's difficult, it means keeping large numbers of large and potentially uncooperative animals around for long period, etc. Here is a WHO document reviewing some of the problems with this approach.
A third approach is to make monoclonal antibodies. This is the most popular approach now; it lets you make sterile, safe antibodies with completely defined characteristics, with minimal risk of contamination, under controlled conditions.
There are many monoclonal antibodies out there that are used in modern medicine, including some that are used to treat pathogens. However, it's worth pointing out that antibodies are not magical panaceas; they're often much less effective than conventional antibiotic or antivirals and are often more expensive and less practical to use.