Inclusion of industrial egg residue in the feed of laying hens to replace limestone: digestibility, productive performance and egg quality.

Abstract

Our objective was to determine whether inclusion of industrial egg residue (IER) in the diets of laying hens would replace calcitic limestone without interfering with productive efficiency, egg quality or digestibility. In a first study (Experiment I), we used 30% IER in the diets of laying hens and found that the apparent digestibility coefficients were 51.6%, 42.8%, 51.6% and 17.8% for dry matter, crude protein, calcium and phosphorus, respectively. In the second study (Experiment II), we compared a control diet containing calcitic limestone with four diets containing increasing levels of IER, in proportions of 25%, 50%, 75% and 100%. During the first cycle (day 1-28), there was no difference between treatments in terms of productive performance or egg quality. During the second production cycle (day 29-56), we observed less food consumption by birds that ingested the highest levels of IER (100% substitution) than in controls. During the third cycle (day 57-84), we found that the inclusion of IER negatively affected performance, particularly lower production numbers, lower egg mass and higher feed conversion. Finally, during the third cycle, chickens broke and ingested their eggs shortly after laying. We conclude that the use of industrial egg residue cannot replace limestone in the feed of commercial laying hens, because it reduces performance and affects egg quality.