Watery whites
Description
When an egg broken onto a flat surface has a watery, spread-out white, this usually indicates that the egg is stale. The height of the white and the weight of the egg are used to calculate a value in Haugh units on a scale of 0 to 110; the lower the value, the staler the egg.
A minimum Haugh unit measurement of 60 is desirable for whole eggs sold to the domestic consumer. Most eggs leaving the farm should average between 75 and 85 Haugh units.
Incidence
The development of watery whites is chiefly due to the increasing age of the egg. The rate of development is increased by high storage temperature and low humidity (see figure 4). As birds age, the Haugh unit value of their eggs decreases by about 1.5 to 2 units per month of lay (see figure 3). Some birds consistently produce eggs with watery whites (Haugh units less than 30) later in lay.
| Cause | Control |
|---|---|
| Old eggs | Minimise storage time on the farm by:
• increasing the number of pick-ups per week for grading or delivery to retail outlets. • collecting and packing eggs laid on pick-up days so that they are consigned on that day. • grading eggs while they are fresh when packing them on the farm. |
| High storage temperature and low humidity | Reduce shed temperatures in summer. Collect eggs at least twice daily and even more frequently in summer. Store eggs in a coolroom at a temperature of less than 20 ºC e.g. 12 to 15 ºC (requirements may vary in different countries) as soon as possible after collection. If a humidifi er is not fitted to the cooling unit, place an open tray of water in the coolroom to ensure humidity is kept at 70 to 80%. Oil eggs soon after collection. Use only an oil such as Caltex Pharma White 15 BP/USP approved for this purpose by the relevant authorities. |
| Ageing of bird | Keep flock age as low as economically possible. |
| Diseases, e.g. infectious bronchitis and egg drop syndrome | Follow effective vaccination programmes. |
| Fungal toxins | Do not allow feed bins or feed lines to become contaminated by stale, wet or mouldy feed. |
| Ammonia | Control ventilation to keep ammonia levels low. |
| Rough handling | Examine egg handling procedures and equipment, and modify to minimise bumping or shaking of eggs. |
| Incorrect packing | Pack eggs on filler flats with the air cell upwards. |
| Birds which persisently lay eggs with watery whites | Culling these birds is not practicable, as they are hard to identify. The only way of handling the problem is to remove the eggs at grading (like all eggs with watery whites, they are distinguished by an enlarged air cell). |
| Strain of bird | Be aware that some strains produce eggs with a high average Haugh unit rating. |
Figure 4: Effects of egg age and storage temperature on egg Haugh unit value
© The State of Queensland, Australia (through its Department of Primary Industries and Fisheries) and DSM Nutritional Products Ltd., 2007. No part of this publication may be reproduced, copied or transmitted save with prior written permission of Director, Intellectual Property Commercialisation Unit, Department of Primary Industries and Fisheries, GPO Box 46 Brisbane, Queensland, Australia 4001, and DSM Nutritional Products Ltd.