The emission of Madhi does not require Ghusl, but one must make Wudhu after washing the penis and testicles before praying, performing Tawaf or touching the Quran, because when the Prophet (sallallaahu alaihi wa sallam) was asked about it, he said: It requires Wudhu.  And he ordered anyone affected by Madhi to wash his penis and testicles. That which requires Ghusl is only sperm when it is ejaculated due to sexual arousal, or its traces are observed upon waking from sleep, whether during the night or day.
 Tawaf: Circumambulation around the Kabah in Makkah.  Al-Bukhari no 132 and Muslim no. 303.