I guess we'll have to agree to disagree. I view rape as a violent assault of another person - usually female. The instigator uses violent force to demonstrate control, inflict pain, usually both physical and mental. The sexual aspect provides humiliating, tortuous dominance over the other. Any sexual gratification derived is a manifestation of the sociopathic nature of the attacker. This hardly describes an act of copulation between a willing female (or male) and a male animal. It could describe such an act between a male human and a female animal, though I don't believe that is the nature of this thread.

By the way, describing Sharia as a "custom" is like describing the US Constitution as a "historically interesting document". Both describe the basis of rule of law, holding the literal power of life or death over individuals within it's domain. Both set the principles for societal behavior and establish governmental relationships with the citizens within.