Evaluation of the role of Spirulina Platensis in diets containing flaxseed oil on performance, antioxidant status, ovarian follicles, egg shelf life, and yolk fatty acid profile in laying hens

The present study was conducted to investigate the effect of <i>Spirulina Platensis</i> (<b>SP</b>) supplementation in diets containing different levels of flaxseed oil on production performance, antioxidant status, ovarian characteristics, egg quality during storage and yolk fatty acid profile in laying hens. For this purpose, 288 laying hens (Hy-line-W36, 70 weeks of age) were used in a completely randomized design with a 2 × 3 factorial arrangement with 6 replications and 8 birds per replication. The experimental treatments included diets containing 3 levels of flaxseed oil (0, 1.5 and 3 % of the diet) and 2 levels of the SP (0 and 5 g/kg of the diet). The results showed that the use of 5 g/kg of Spirulina in flaxseed oil diet at levels of 1.5 and 3 % significantly improved the laying percentage, egg weight and feed conversion ratio (<i>P</i> < 0.05). Consumption of flaxseed oil without SP caused a decrease in total antioxidant capacity and an increase in malondialdehyde (<b>MDA</b>) in serum and liver, while the addition of 5 g/kg of SP compensated and improved these effects (<i>P</i> < 0.05). The interactive effects indicated that SP supplementation in 1.5 and 3 % flaxseed oil-containing diets had a synergistic effect on large yellow follicles weight (<i>P</i> < 0.05). The three-way interaction (flaxseed oil × SP × storage) revealed that SP supplementation significantly improved Haugh unit values during storage compared to treatments without SP (<i>P</i> < 0.05). In addition, increasing the level of flaxseed oil increased omega-3 unsaturated fatty acids including alpha-linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid (<b>DHA</b>) and decreased the omega-6/ omega-3 ratio in egg yolk, and simultaneous consumption of SP showed more increasing effects on the concentration of omega-3 fatty acids (<i>P</i> < 0.05). Also, a linear and positive relationship was observed between the concentration of DHA in egg yolk and the amount of MDA in liver tissue (r = 0.978, r² = 0.957), indicating a very strong correlation between egg enrichment with omega-3 fatty acids and increased lipid peroxidation in the liver. While a conventional egg supplied only one-twentieth and one-sixteenth of the daily omega-3 requirement for men and women, respectively, a single enriched egg with 3 % flaxseed oil plus SP provided approximately one-eighth of the daily requirement for men and one-seventh for women. In general, the addition of flaxseed oil to the diet of laying hens, while improving production performance and yolk fatty acid profile, increased lipid peroxidation and decreased egg stability during storage. However, simultaneous supplementation with SP not only increased production performance and ovarian follicles, but also can be an effective strategy to produce functional eggs with enhanced health benefits, improved oxidative stability, and extended shelf life.