7 CFR §91.6

1. (a)Services may be furnished whenever a Science and Technology staff is available and the facilities and conditions are satisfactory for the conduct of such service.
2. (b)Laboratories may provide limited service on Saturdays and Sundays at a premium fee. Weekend service may be obtained by contacting the laboratory director or supervisor.
3. (c)Holiday and overtime laboratory service may be obtained with a minimum 24 hour advance notice, at a premium fee, by any prospective applicant through the laboratory director or supervisor.