8.2 Feed extract for standard curve A feed extract (8.1) can be used for the standard cu (see 11. Remarks: feed extract are transferred to a 50 ml on tubes and the extract 11.8). 50 centrifuged min (10'000g). for 10 ice before use. The supernatant is transferred to a new tube and kept for 15-30 minutes on If blank feed is available (see 11. Remarks: 11.1, 11.4 to 11.8), extract 50 g as described under 8.1 Feed samples.