Exhibit 23 (a) Independent Auditors' Consent We consent to the incorporation by reference in Registration Statement No. 333- 663357 of Neogen Corporation on Form S-8 of our report dated July 23, 2001, appearing in this Annual Report on Form 10-K of Neogen Corporation for the year ended May 31, 2001. DELOITTE & TOUCHE LLP August 24, 2001 Lansing, Michigan