On d 60 of lactation, biopsies of the mammary glands of 8 goats were also performed after challenge with ACTH or the placebo. The 8 goats were randomly distributed, with 4 in each treatment. Each biopsy was performed 30 min after the administration of ACTH or the placebo. After trichotomy, antisepsis, and anesthetic procedures, the skin incision was performed at the medial part of the gland with a scalpel. The disposable biopsy needle was inserted into the incision to a depth of approximately 3.0 cm, and the equipment was triggered to cut and collect a sample of approximately 2.0 × 0.5 cm of mammary tissue. Three tissue samples were collected. The first was collected to use in determining the rates of apoptosis and proliferation, the second was used for the analysis of gene expression by reverse-transcription (RT) PCR, and the third was used for cell cultures and the subsequent administration of in vitro treatments.