Tolerance and efficacy study of palygorskite incorporation in the diet of laying hens

The objective of this study was to assess the safety and effectiveness of palygorskite inclusion in the diet of laying hens. A total of 135 Lohmann Brown hens, aged 21 weeks, were randomly assigned to one of three treatment groups (n = 45): group C (control), group S (fed a diet with 1% palygorskite, standard-level) and group T (fed a diet with 9.1% palygorskite, multi-fold of standard-level). All hens were kept in commercial laying cages (3 hens per cage, 15 replicates per group). Hens of group T were used only for the first eight weeks (tolerance study period), while hens of groups C and S were kept for another sixteen weeks (efficacy study period). In each group, laying percentage, feed intake, feed conversion ratio, mortality and egg quality characteristics were assessed. The results showed that feeding a ration with 9.1% palygorskite (group T) did not have any negative effects on laying percentage (%), feed conversion ratio or health of hens. However, the body weight of hens in group T was significantly lower (P < 0.001) while their feed intake was higher (P < 0.001) compared to those of groups C and S for the 8-week experimental period. Furthermore, the produced eggs had significantly (P < 0.001) lighter coloured egg yolk. The incorporation of 1% palygorskite in the ration for 24 weeks improved laying percentage (by 2.6%, P < 0.05) and feed conversion ratio (by 4.6%, P < 0.05); feed intake and body weight of hens were unaffected. The produced eggs had significantly lighter eggshell and yolk colour (P < 0.001) as well as increased eggshell thickness (P < 0.05). It was concluded that palygorskite is a tolerable material which has the potential to improve laying hen performance and influence egg quality traits when used at recommended levels.