Effect of using probiotics and different forms of calcium carbonate in diets containing different levels of protein on production performance and egg characteristics in laying hens

Abstract

Introduction: The purpose of this experiment was to investigate the effects of two levels of
Primalac probiotics on two forms of calcium carbonate and two levels of protein on functional
and quality traits of laying hens.
Materials & Methods: This study was performed on 160 laying hens of Leghorn Hy-line W-36
at the age of 43 weeks for 7 weeks in a randomized complete block design with 2×2×2 factorial
arrangements with two levels of probiotic (zero and Recommended) two forms of calcium
carbonate (flour and granules) and two levels of protein (90 and 100 % of Hy-Line W-36
recommendations) with 8 treatments and 5 replications and 4 pieces of chicken in each
replication, a total of 40 experimental units were performed. Functional traits of laying hens were
measured daily and weekly and parameters related to egg quality were measured at the end of the
seventh week of the experiment.
Results: Feed intake in optimal protein treatment was lower than in low protein treatment. be that
it was significant (P<0.05). A significant interaction was observed in terms of yolk index between
two probiotic factors and protein, protein decrease had a negative effect on yolk index and caused
a decrease in yolk index (P<0.05). Crust thickness with protein and calcium carbonate had
significant positive interactions, so the addition of probiotics increased crust thickness by
reducing dietary protein levels (P<0.05).
Conclusion: The experimental results showed that reducing dietary protein increased feed intake
and decreased shape index, but adding probiotics could partially offset the effects of protein
reduction.