Abstract MOTTLED yolks, often observed in stored eggs and less frequently in fresh eggs, were reported more than 30 years ago (Almquist, 1933). Yet, knowledge of determinants of yolk mottling are limited primarily to the effects of “Nicarbazine” as reported by many workers including Polin and Porter (1956), Weiss (1957) and Baker et al. (1957), and of free gossypol found in many cotton seed products (Heywang et al., 1955; and many others). More recently, piperazine compounds have been shown to influence yolk discoloration (Beane et al., 1965). In other work in this laboratory it was noted that eggs transported for long distances tended to have more mottling than those moved for short distances. It was hypothesized that physical movement, time and temperature during transport might be causative factors. This study was initiated to determine the effect of physical movement of two types, short time holding and temperature on mottling of egg …