The effects of dietary supplementation with rosemary (Rosmarinus officinalis L.) essential oil on laying hen performance, egg quality, some blood parameters and small intestine microflora

In this research, the effects of feeding laying hens with antibiotic, vitamin E and different doses of rosemary essential oil supplementation on performance, egg quality, egg yolk, fatty acid composition, cholesterol and vitamin E levels, lipid peroxidation malondialdehyde (MDA) levels during storage, some blood parameters, and beneficial and harmful microorganisms in small intestine microflora were investigated.In this study, a total of 240 Bovans white laying hens, 32 week-old, were allocated randomly into 6 groups according to the randomized plot experimental design; each group had 5 replications and each replicate had 8 hens. Treatment groups were 1. group (Negative Control) standard basal feed, 2. group (Positive Control) 500 mg//kg antibiotic (Chlortetracycline), 3. group (200 mg/kg) vitamin E, 4. group rosemary essential oil (100 mg/kg ), 5. group rosemary essential oil (200 mg/kg ), 6. group rosemary essential oil (300 mg/kg ). Study period lasted 90 days. Body weight, egg production, egg weight, damaged egg ratio, eggshell weight, eggshell thickness, eggshell breaking strength, egg shape index, egg yolk index, albumen index, Haugh unit, egg yolk colour, some blood parameters and egg yolk cholesterol levels were not affected by the supplementations of the basal feed.All feed supplementations comparing to the negative control group showed a positive effect by reducing the consumption of feed (P<0.05), and excluding the antibiotics and rosemary 100 mg / kg doses increased the feed conversion ratio (P<0.05).Feed supplemented with 100 mg/kg rosemary essential oil increased the amount of total monounsaturated fat (MUFA) and oleic acid significantly (P <0.05), whereas it decreased the amount of total polyunsaturated fatty acids (PUFA) and linoleic acid significantly (P <0.01). With 100 mg/kg rosemary supplementation storage of 42 and 56 days, with 200 mg/kg vitamin E supplementation in all storage periods reduced the egg yolk MDA levels (P<0.05). Eggs from chickens fed with vitamin E (? - tocopherol acetate) supplemented feed had significantly higher vitamin E levels (P<0.001).Antibiotic and all dose of the rosemary essential oil effected the content of bacteria in the jejunum and probably decreased the numbers of coliform (P<0.05), fecal coliform (P<0.001), Escherichia coli (P<0.001), and Clostridium perfringens (P<0.001) significantly. 100 mg/kg rosemary essential oil and 500 mg/kg antibiotic supplementation had the same effect on the bacterial content examined, while probably 200 mg/kg and 300 mg/kg rosemary essential oil was found to be more effective than antibiotic supplementation on fecal coliform and Escherichia coli. In conclusion, rosemary essential oil showed dose-dependent antimicrobial and antioxidant effect. When considering the most important parameter which is feed conversion ratio, supplementation with 200 mg/kg rosemary essential oil, when considering the general parameters of lipid metabolism 100 mg/kg rosemary essential oil can be recommended for laying hen.