Effects of different proteases on commercial laying hens at peak production

Abstract

We evaluated the effect of adding proteases in diets of laying hens atpeak production on the performance, egg quality, relative weight of digestive organs,and intestinal morphometry. Hy-Line W36 layer hens (390; 28-39 weeks old) weredistributed in five treatments, with 13 animals each, with six replicates. The treatmentswere: control (standard formulation without nutritional reduction or protease inclusion),negative control A - NCA (nutritional reduction according to protease A matrix, withoutprotease), negative control B - NCB (nutritional reduction according to protease B matrix,without protease), NCA + protease A, and NCB + protease B. The experimental periodlasted 12 weeks, divided into three cycles of 28 days. Hens subjected to treatments (NCAand NCB) showed a decrease in feed intake. However, the addition of proteases A and Bpromoted improvement in this trait. The diets NCA and NCB had a negative influence onthe production rate of the hens, but the diet supplementation with protease B resultedin significant improvement on egg laying rate. Hens subjected to nutritional reductionpresented the worst results regarding mass and conversion by egg mass. However, theaddition of enzymes reversed these results. Although the diets did not affect the relativeweights of yolk, albumen, eggshell, Haugh unit, and specific gravity of the eggs, a highereggshell thickness was observed in hens that received NCA, NCB, and NCB + protease Bdiets. The diets did not influence the relative weights of digestive organs and the smallintestine morphometry. Hens fed diets supplemented with A and B have performancerecovered in relation to those that received diets with reduced levels of nutrients