In fact when collagen is hydrolyzed, its large triple helix chains of amino acids are broken down into small peptides of amino acids where they are absorbed, digested and delivered to their site of action in our body, so it doesn't really make a difference to which animal source the collagen peptides are produced from (the amino acid composition is the same for collagen from for example fish, bovine or porcine). It really comes down more to the preference of individuals.