Excluding disease, the single most important factor affecting the albumen quality of freshly laid eggs is the age of the birds. With advancing flock age, Haugh unit scores decrease and the variability of the scores increases. An induced pause in egg production (moult) can often restore albumen quality in aging hens. Both strain differences and strain/age interaction effects in Haugh unit scores of fresh eggs have often been observed, but these are normally small and have little practical significance. Albumen quality of the egg is not greatly influenced by bird nutrition. .
When ambient temperatures are high, delays in egg collection increase the rate of Haugh unit score decline. The maintenance of albumen quality during egg storage is dependent on the eggs being cooled quickly following lay and subsequently being held at low temperatures.
Different strains of hens can show a great variation in Haugh unit scores. Strains laying white-shelled eggs have been shown to be much less variable than those producing brown-shelled eggs.