Hoglin/zoglin attacking animation is not smooth

The bug

When hoglin/zoglin attacks other mob, the animation of it displays strangely, which seemed to have low frames, while most other mobs' attack animation appears fluently. (e.g. iron golem's attack animation)

How to reproduce

1. /summon zoglin ~ ~ ~ {Attributes:[{Base:0.0d,Name:generic.attack_damage}]}

   /summon zoglin ~ ~ ~ {Attributes:[{Base:0.0d,Name:generic.attack_damage}]}

2. /gamemode survival

   /gamemode survival