Effect of rare earth element-yeast on egg production, nutrient digestibility, egg quality, blood profiles, excreta gas emission, and excreta microbiota in laying hens

Abstract Text: Rare earth elements (REE) are considered as an alternative to antibiotic because they have the similar action to antibiotic. Rare earth elements-yeast, an improved form of organic REE, may be more effective when fed to livestock because of the lower REE concentration. The objective of this study was to determine the effects of REE-yeast on egg production, nutrient digestibility, egg quality, blood profiles, excreta gas emission, and excreta microbiota in laying hens. A total of 216 ISA brown laying hens at 52 weeks of age were used in this 5-week feeding trial. Treatments consisted of soybean meal based diets supplemented with 0, 0.05, and 0.1% REE-yeast. All birds were allotted to 1 of 3 treatments with 6 replicates (12 hens per replication). All diets were formulated according to recommendations of the manual of the breeder for ISA brown and to meet NRC (1994). During wk 1 and 2, laying hens fed 0.05% and 0.1% REE-yeast had a higher egg production (90.33, 92.67 vs. 87.00 %; 90.33, 92.50 vs. 86.67 %; P < 0.01) than those fed diets without REE-yeast and egg production improved (linear, P < 0.01) as dietary REE-yeast increased in the diet. During wk 3, 4 and 5, laying hens fed 0.1% REE-yeast had a higher egg production (92.50 vs. 86.83 %; 92.33 vs. 86.33 %; 92.17 vs. 85.67 %; P < 0.05) than those fed without REE-yeast. Nitrogen digestibility (65.22, 66.31, 69.22 %; linear, P = 0.03) increased with increasing REE-yeast levels in the diet, and the greatest value was observed in laying hens fed 0.1% REE yeast. In wk 4, laying hens fed REE-yeast had higher yolk height (9.25, 9.58, 9.72 mm; linear, P < 0.01) and Haugh unit (92.79, 96.63, 97.11; linear, P = 0.01) increased with increasing REE-yeast in diets. In wk 5, Haugh unit (94.53, 97.17, 95.60; P < 0.05) increased quadratically with increasing REE-yeast levels in the diet. At the end of experiment, ammonia tended to decrease linearly (15.25, 13.25, 12.75 ppm; P < 0.1) with increasing REE-yeast in the diet. However, effects were not observed in blood profiles and excreta microbiota. In conclusion, dietary supplementation with REE-yeast improved egg production, nutrient digestibility, and egg quality in laying hens.

Keywords: egg production, egg quality, laying hen, nutrient digestibility, rare earth elements-yeast