# The Feeding Stuffs Regulations 1991, Paragraph 6


No material shall contain any added vitamin, pro-vitamin or substance having a similar effect except that—
(i) any material for any animal of a kind specified in column 3 of Chapter A of Part V may contain added vitamin D2 or D3 (but not both) in proportions which, taking account of any such vitamin which is naturally present, do not exceed the maximum content specified in column 4 of the said Chapter in relation to the kinds of animal specified in column 3 thereof, and provided that the conditions (if any) specified in column 5 of that Part are complied with;
(ii) any material for any animal of a kind specified in column 3 of Chapter B of Part V may contain any vitamin (other than vitamins A, D2 or D3) or any pro-vitamin or chemically well defined substance having a similar effect in proportions which, taking into account any such substance which is naturally present, do not exceed the maximum content (if any) specified in column 4 in relation to the kinds of animal specified in column 3 thereof.

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Source: https://www.legislation.gov.uk/uksi/1991/2840/schedule/4/paragraph/6 (the official version)
Page: https://openlegislation.uk/feeding-stuffs-regulations-1991/schedule-4/paragraph-6
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.