An adaptor fitting 10 by which an animal feeding teat can be mounted to a feeder F. The adaptor 10 has a first section 11 to which the feeding teat can be fitted. A second section 12 is engagable with the first section 11. The first and second sections 11 and 12 are, in use, engagable through an opening O in the wall W of a feeder F such that the first and second sections are respectively located at the outer and inner sides of the wall W. The second section 12 has a sealing part 26 that, upon relative movement between the first and second sections 11 and 12 during fitment of the adaptor to the wall W, engages into the material from which the wall W is made. This creates a seal around the opening O in the wall W.
