Inclusion of guanidinoacetic acid in the diet of laying hens at late phase of feeding

Abstract

Context There are few studies on the effects of guanidino acetic acid (GAA) on the performance, quality and fortification of eggs from commercial laying hens. Aims This study aimed to evaluate the effects of dietary supplementation with GAA in the diet of laying hens on productive performance, economic viability and the quality and fortification of eggs. Methods In total, 720 semi-heavy 101-week-old Lohmann LB-Lite® laying hens were distributed in a completely randomised design consisting of five treatments defined by the dietary GAA concentration, with six replicates of 24 birds per experimental unit. Diets were formulated to contain 0.00, 0.05, 0.10, 0.15 or 0.20% GAA. Productive performance and economic viability were evaluated for 12 weeks. Egg quality and fortification were evaluated at 4 and 12 weeks post-GAA inclusion. Key results A negative linear response was found for the bird final weight with an increasing GAA concentration and the optimal value for feed conversion per dozen eggs, as determined by quadratic regression model, was 0.12% GAA. After 4 weeks of GAA inclusion, egg-specific weight responded linearly and positively and yolk colour had a quadratic response, with an optimal concentration at 0.12% GAA. After 12 weeks of GAA inclusion, the optimum level for yolk colour was 0.14% GAA. The treatments did no affect creatine fortification of eggs. Economic analysis showed a linear increase in feed cost with an increasing dietary GAA level. The diet with the best feed cost per kilogram of dozen eggs produced was that with 0.12% GAA inclusion level. Conclusion The inclusion of 0.12% GAA in the diet of commercial laying hens influenced performance parameters and egg quality without fortifying egg creatine concentrations. Implications An egg is a very accessible food and enrichment is a good alternative, as it would help increase consumption of egg nutrients. New research with other products is fundamental for a greater diversification of enriched eggs and better service to consumers.