Abstract:
The objective of this research was to assess the quality of table eggs from two different strains of layers at different ages raised in two distinct housing systems using both conventional (breaking of eggs) and non-conventional (near-infrared spectroscopy) methods. The study was done in two parts, namely: the use of conventional method and the use of non-conventional or the Near Infra-red Spectroscopy (NIR) method for the egg quality assessment. In all five (5) different experiments, namely: physical, nutritional, microbiological, organoleptic egg quality assessment and presence of antibiotic residues in eggs, were carried out. In the first phase of the experiment, a total of 2,490 freshly laid eggs from the two layer strains (Lohmann brown and Lohmann white) aged 24, 39, and 68 weeks, raised in deep litter and battery cage systems, were randomly assessed for the physical, nutritional, microbiological, and organoleptic properties of the eggs as well as the presence of antibiotic residue. The data obtained were subjected to a three-way analysis of variance using the General Analysis of Variance of GenStat (Discovery edition), with strain, housing system, and layer age as fixed factors. The second phase of the study involved the possibility of using the NIR method to predict the physical, nutritional, microbiological and presence of antibiotic residues in the egg. Results obtained from the conventional experiment showed some significant effects of the fixed factors on some of the important physical egg characteristics such as egg weight and egg freshness (Haugh unit); an indication that for improved physical characteristics of eggs, the strain of layers used, the age of the layers when eggs are laid and the type of housing system used for egg production are very important. The portable NIR spectrometer, along with qualitative algorithms, indicated that eggs stored under room temperature had a 95.54% identification rate at five principal components. On the other hand, eggs stored in cold storage had a 100% identification rate at five principal components for determining the lay date. In the independent set, PLS-R produced R = 0.87 and RMSEI = 2.57 for ambient storage, and R = 0.88 and RMSEI = 2.66 for cold storage. Data obtained from the conventional experiments showed significant strain, housing and age effects on the egg internal qualities proximate content and sensory properties of eggs but showed no significant effects on the microbiological properties of eggs. The novel handheld NIR spectroscopy was able to classify (PCA-MSC-LDA gave IR = < 95%) and predict the freshness, storage duration (MSC-PLSR of R = 0.83) and proximate content of eggs. The data from conventional experiments largely correlated with the NIR spectroscopy. The research indicated that portable NIR spectroscopy methods might be employed as a rapid, nondestructive tool for simultaneous egg examination. Moreover, distinct consideration should also be directed to protect eggs against contamination ensuring on-farm biosecurity, reducing cross-contamination, and inspection of eggs and poultry feed.
