For example, Jewish kosher and Islamic Halal customs require gelatin from sources other than pigs, like cows and/or fish and from animals slaughtered ritually. Roma people are cautious of gelatin products that may have been made from horses, as their culture forbids the consumption of horses.n a commercial scale, gelatin is made from by-products of the meat and leather industry. Recently, fish by-products have also been considered because they eliminate some of the religious obstacles surrounding gelatin consumption. Gelatin is derived from pork skins, pork, horses, and cattle bones, or split cattle hides.