Modelling Conditions for Quality Egg Storage Using Randomized Complete Block Design
Gogo, Jacqueline Akelo
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Rearing chicken has contributed positively to global nutrition, especially egg production. This practice attracts both large and small-scale poultry keeping within the world’s economy. Egg storage has been a problem due to ineffective methods subjecting many farmers and egg retailers to losses. These methods include various models involving statistical analysis of the storage conditions on the egg quality. However, they do not provide sufficient information. Therefore, confusion persists between the use of fixed and mixed-effect models. The confusion is because some studies analyse randomized complete block design as fixed while others as mixed effect models. Apparent deficiencies of the evidenced information from the randomized complete block design model prompted this study. The quality of the eggs was determined by the physical characterization and changes of both external and internal properties under different temperature conditions and storage duration. The study evaluated the effect of storage temperature at three levels (5 o C, 19.5 o o ) on egg quality using fixed and mixed-effects models. This study used a total of 618 fresh and unfertilized eggs from the ISA (Institut de Sélection Animale) brown layers. Restricted maximum likelihood and analysis of variance methods were used to determine the efficiency of fixed and mixed effect models. Results showed that the physical components of the egg were significantly affected at 5 C and 30 C) and time at four levels (2 nd th nd , 12 , 22 nd and 32 o o C, 19.5 o P ( 0.05). C and 30 C The effect was more adverse on eggs stored o at 30 C for 32 days. However, storage temperatures of 5 o o C and 19.5 C led to an extensive reduction in the Haugh unit, yolk index, and egg white. Contrariwise, it increased the weight loss, the albumen diameter under storage for 2 nd th nd , 12 , 22 nd , and 32 -time intervals. This study recommends a temperature of 5 o C for egg quality preservation. The eggs should be reserved in fridge-freezers for 32 days, at 19.5 o C for fourteen days, and at 30 o C for seven days maximal. The fixed-effect models exhibited smaller components in diameter and height of albumen, yolk index, weight loss, and Haugh unit. This overlapped instances where the fixed-effect models were significantly the same as the mixed-effect models. This study proposes that the fixed effect model is the most appropriate for randomized completely block design experiments. This study obtained G-optimal efficiency of 68% to predict the optimal levels of egg storage for quality maintenance. This study strongly recommends further studies to consider optimization using other classes of storage conditions.