This probe allowed penetration of up to 14 cm into mammary tissues. Contact gel (Zero-gel, ECG-EEG, Asept InMed, Quint Fonsegrives, France) was applied to the skin of the udder to exclude air between the probe and the udder. Scans were performed in the stalls with cows standing, and care was taken to use the same position for each cow and probe between measurements at each sampling period, with the probe close to and parallel to the teat and pointing directly toward the udder cistern. Images were transmitted to a computer and analyzed using image analysis software