Thyme (Thymbra spicata L.), rosemary (Rosmarinus officinalis L.) and vitamin E supplementation of laying hens
This study was conducted to determine the effects on performance, egg quality parameters and some serum profiles of vitamin E, thyme and rosemary extracts that were added to laying hen feeds. One hundred twelve 48-week-old Bovans-genotype white laying hens were used in the research. In the study, hens were randomly divided into four groups, each comprising of four replicates of seven hens. The first group was fed with the basal diet as a control. The other three groups were fed diets with 200 mg/kg vitamin E, with 1000 mg/kg thyme, and with 1000 mg/kg rosemary for eight weeks. As a result, vitamin E increased egg production statistically compared with feeds with plant extracts. Thyme-supplemented feed increased egg weight significantly. However, it reduced egg production. Rosemary supplementation generated profit by reducing the feed intake, but had a negative effect by reducing egg weight and egg production. The cholesterol level in the blood serum decreased with thyme supplementation. In addition, blood triglyceride level decreased at a statistically significant level with the supplementation of both thyme and rosemary. In the light of these results, it can be said that the supplementation of vitamin E, thyme and rosemary extracts has a positive effect on some performance parameters and animal health. Since healthier products are obtained from healthy animals, the use of these natural additives in laying hen feeds could be recommended after dose trials.
Keywords: aspartate aminotransferase, cholesterol, egg production, feed intake, plant extract, triglyceride