Effect of dietary energy and protein on the performance, egg quality, bone mineral density, blood properties and yolk fatty acid composition of organic laying hens

An experiment was conducted to evaluate the effect of dietary metabolizable energy (ME) and crude protein (CP) on the performance, egg quality, blood properties, bone characteristics and yolk fatty acid composition of organic laying hens. At 23 weeks, a total of 600 Brown nick laying hens were randomly distributed into 24 outdoor pens (4 replicate pens/treatment; 25 birds/pen) and were given (2750, 2775 and 2800 kcal of ME/kg) and CP (16 and 17%) resulting in a 3×2 factorial arrangement of organic dietary treatments. The experiment lasted 23 weeks. The performance of laying hens were not affected by the dietary treatment while the egg weight was increased with energy and CP levels in the diet (P<0.05). Serum total protein was not affected by dietary energy and protein level. Total cholesterol and triglyceride tend to reduce with the increasing amount of CP in the diet. Thereafter, bone and egg quality characteristics were numerically increased in dietary 2775 kcal of ME/kg and 16% CP treatment. On the other hand, docosahexanoic acid content in egg yolk was higher (P<0.01) in 2750 kcal of ME/kg and 17% CP treatment. As a result, the performance, blood and fatty acid composition were maximized in 2750 kcal of ME/kg and 16% CP treatment. Thus, dietary 2750-2775 kcal of ME/kg and 16% CP may enhance performance, blood and fatty acid composition of organic laying hens.