Effects of Storage Method and Period on Egg Quality Traits of Brown Egg Type Chickens in Zaria Local Government Area of Kaduna State

Abstract

A study was conducted to examine the effects of storage method and period on egg qualities of brown egg type chickens s in Zaria local government area of Kaduna state. A total of 50 eggs were used. 10 were used initially to test for the parameters of fresh egg (not subjected to any form of storage) while the remaining 40 eggs were divided into four groups with each group having 10 eggs. The ten (10) eggs were randomly assigned to one the four storage methods. Of the 10 eggs in each of the storage methods, 8 were picked at random after the following storage periods (1, 2, 3, 4, 5 and 6 weeks) for the determination of egg quality traits. The first storage method (T1) was room temperature, the second (T2) was sawdust, the third (T3) was oiling while the fourth (T4) was refrigeration. Egg samples were randomly selected for each storage media and tested at weeks 1, 2, 3, 4, 5, and 6. At sampling, the eggs were weighed and broken onto a flat surface with a table knife to cautiously crack the shell without breaking the vitelline membrane. The external egg quality parameters measured include egg weight, egg length, egg width, the shape index, shell weight, and shell thickness while the internal parameters measured were yolk width, yolk height, albumen height, albumen width, albumen weight, yolk index, albumen index, Haugh unit, and the potential hydrogen ion concentration (pH). Data collected on egg qualities were analyzed using General linear model of SPSS with storage time and method as fixed factors, and means with significant differences were separated using Duncan’s Multiple Range Test. The results obtained indicated that storage method was found to have significant (P>0.05) effect on egg weight and shell weight. The mean weight of fresh eggs before storage was 64.79 g while the weights after storage were 56.15, 56.48, 63.86, and 59.45g for room temperature, sawdust, oiling, and refrigeration, respectively. Oiling had the least weight loss followed by refrigeration while sawdust and room temperature had the greatest weight loss.  The effect of storage time was statistically significant (P<0.05) for all parameters except egg width, shape index and shell thickness. There was a general decline in egg weight from 64.79 g in fresh egg to 54.60 g at the 6^th week of storage. Egg height for fresh eggs was not significantly (P>0.05) different from weeks 1, 2, 3, 4 but 5 differed (P<0.05) from that of week 6. The effect of storage time was statistically significant (P<0.05) for most parameters except yolk weight, albumen and yolk pH.  The highest albumen width was observed at week 4. At weeks 5 and 6, the albumen had no dimension as the thick albumen turned watery. Dramatic deterioration was observed in albumen height (0.70 to 0.26), yolk height (1.64 to 0.59), albumen index (9.06 to 3.54), yolk index (40.13 to 12.06), and Haugh unit (80.21 to 38.52) and an increase in albumen. In conclusion, to achieve optimal external egg qualities, such as egg weight and shell weight, it is best to use fresh and oiling storage methods and for storage period, eggs should not be stored for more than five weeks. For maintaining quality albumen width, storing eggs at room temperature or using sawdust is recommended. For other internal egg qualities like albumen height, yolk height, Haugh unit, yolk index, and albumen index, fresh and refrigeration methods are most effective.