Effects of dietary olive oil on egg quality, serum cholesterol characteristics, and yolk fatty acid concentrations in laying hens

A total of 252 Hy-Line laying hens were used to evaluate the effects of dietary olive oil on egg production, egg quality, serum cholesterol characteristics, and yolk fatty acid (FA) concentrations. Layers were randomly allocated into three treatments with seven replications for 4 weeks. Dietary treatments were: CON (control diet, 5% tallow), OLO2 (3% tallow + 2% olive oil), and OLO5 (5% olive oil). Throughout the experimental period, yolk color was greater in OLO5 group than CON group (P < 0.05). The OLO2 and OLO5 groups showed greater egg shell breaking strength than CON group (P < 0.05). Egg shell thickness was increased in OLO2 and OLO5 groups compared with CON group (P < 0.05). The total serum cholesterol concentrations in OLO2 and OLO5 groups were lower than CON group (P < 0.05). Serum high-density lipoprotein cholesterol was elevated in OLO2 and OLO5 treatments compared with CON group (P < 0.05). Layers fed OLO2 diet had greater serum low-density lipoprotein cholesterol concentration than those fed CON and OLO5 diets (P < 0.05). Total yolk unsaturated fatty acids (UFA) were greater in OLO2 treatment compared with CON group (P < 0.05). In conclusion, 2% or 5% olive oil could improve yolk color, increase total yolk UFA, and decrease serum cholesterol concentration in laying hens.