Effects of single or combined dietary supplementation of boric acid and plant extract mixture on egg production,egg quality and blood cholesterolemia in laying hens [Yumurtaci{dotless} tavuk rasyonlari{dotless}na İlave edilen borik asit ve/veya bitki ekstrakti{dotless} kari{dotless}şi{dotless}mi{dotless}ni{dotless}n yumurta verimi ve yumurta kalitesi ile kan kolesterolü üzerine etkileri]

This experiment was conducted to determine the effects of boric acid (ba) (60 mg/kg of feed) and plant extract mixture (fitococci,f) (0.75 g/kg of feed),individually or in combination,on egg production,egg quality parameters and blood cholesterol concentration of laying hens in 23 wk of age. after wk 7 of the trial the level of boric acid in feeds were increased to 180 mg/kg. the feeding period lasted 14 wk. one hundred ninety-two pullets (hyline) were randomly divided into control and 3 treatment groups each containing 48 birds and 6 replicates (each with 8 birds). at the end of the experiment there were no significant effects of dietary boric acid and plant extract mixture inclusion on feed efficiency,egg weights and egg production,egg quality parameters (shell thickness,breaking strength,and shape index) compared with control. but feed intake of hens which were supplemented with plant extract mixture and boric acid were increased (p<0.01). it was also determined that there were no effects of treatments on blood cholesterol levels. as a result,since hens which were fed with basal diet plus plant extract mixture showed better feed conversion ratio at 9-10 wks,this combination of feed additives can be added to diets without any adverse effect on laying hens. but inclusion of 60 mg/kg boric acid is considered better than 180 mg/kg with regard to feed efficiency in laying hens.