Contents and Quality of Fatty Acids of Eggs Produced in Local Housing System Compared to Standards of Columbus Eggs

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Elhaj, Arafa Abdallah Mohammed
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University of Khartoum
Abstract
This study was designed to investigate the effect of domestic commercial layer housing system on egg yolks fatty acids contents and quality compared to standards Columbus eggs (designed or enriched omega-3 eggs). Based on records of Inma’s chicks producer company, three layer farms were selected for sampling experimental eggs. The selected farms shared the same layer breed (Lohman), age (32wk) and diet, but they differed in layer housing systems (open sided, closed and semi closed) .Through 3 successive months (March – May 2015), 270 eggs were randomly collected from hens housed under each of the three housing systems. In each month, the collected eggs were divided into three replicates of 30 eggs each, then transferred to the laboratory for fatty acids analysis following the procedure of Folch et al.(1957). The obtained data were subjected to ANOVA using SPSS (2010). The results indicated that eggs laid under the closed housing system vs. the other 2 systems recorded significantly (p≤ 0.05) lower amount of palmitic acid (C16:0) but higher in caprylic (C8:0), pentadecanoic (C15:0) and heptadecanoic (C17:0) acids. The contents of C16:0 in eggs of hens under the three housing systems were the highest (26.29-61.07%) in comparison to the other saturated fatty acids which ranged between 0.001 - 0.76 %. Likewise, eggs produced under the closed layer housing system contained significantly (p≤ 0.05) higher percentages of all determined monounsaturated fatty acids (palmitoleic,C16:1; heptadecenoic,C17:1; elaidic,C18:1; eicosenoic,C20:1; and erucic,C22:1) except pentadecenoic,C15:1 which showed significantly (p≤ 0.05) lower percentage (27.27%) than those produced under the open sided (33.26%) or the semi-closed (35.23%) layer housing systems. The polyunsaturated fatty acids were significantly (p≤ 0.05) higher in the closed layer housing system compared to the other two systems with the exception of arachidonic,C20:4 which was the least in eggs of all examined housing systems. Comparing the fatty acids content of the experimental eggs with the standards of Columbus eggs, the results indicated that the contents of C16:0 in the experimental eggs were significantly (p≤ 0.05) higher than the standards of Columbus eggs (26.89-61.07 vs. 19%) . Conversely, the contents of stearic (C18:0), C16:1 and C18:1 were significantly (p≤ 0.05) lower in the experimental eggs compared to standards of Columbus eggs. The standards of Columbus eggs also revealed significantly (p≤ 0.05) higher levels of polyunsaturated omega-3 and omega-6 fatty acids than the experimental eggs. The variation between the standards of Columbus eggs and the eggs under the three layer housing systems was also indicated by the ratios of total polyunsaturated fatty acids to total saturated fatty acids ; total omega-6 to total omega-3 fatty acids; and total long chains of omega -6 to omega-3 fatty acids. The ratios of standards of Columbus eggs for the former two categories were almost 1:1, whereas the ratio for the latter category of the long chain fatty acids was 0.32:1. The corresponding ratios in the experimental eggs ranges were 0.01-0.3:1, 3.07-204:1, and 2.66-274:1, respectively, which apparently differed from the standard ratios of Columbus eggs. Based on the presented results, the local layer hens housing system had a significant (p≤0.05) effect on eggs' fatty acid contents and quality. Eggs produced under the closed housing system showed significantly (p≤ 0.05) lower omega-3 and omega-6 fatty acids contents than the standards of Columbus eggs but these contents were higher than the contents of eggs produced under both the open sided and the semi-closed housing systems. It is recommended to conduct more studies to explore the reasons behind the apparent disparity in the features and quality of fatty acids of eggs produced by local housing system.
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Fatty Acids of Eggs Produced; Local Housing System; Columbus Eggs
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