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Yeast fermentation products are commercially available for inclusion in poultry diets. Due to the various yeast species and strains used, fermentation conditions, processing methods, and bioactive compound concentrations generated, many different forms of yeast by-products exist. Numerous studies have examined the impact of various gut health-targeted additives such as prebiotics, probiotics and postbiotics on laying hens, but much less is known about current commercial yeast products on egg production or the GIT microbiota in laying hens. Therefore, the objective of the current study was to conduct an initial comparison of commercial yeast products with different expected modes of action in laying hen diets on egg production parameters and the corresponding impact on the cecal microbiota.
A short-term feeding study was carried out to test commercial yeast products: Citristim (an inactivated whole cell yeast (Pichia guilliermondii) postbiotic) at 0.5 kg/tonne, Maxi-Gen Plus (processed yeast containing nucleotides, β 1,3-glucans and mannans) at 1.0 kg/tonne, Hilyses (hydrolyzed product derived from Saccharomyces cerevisiae, consisting of peptides, free amino acids, nucleotides, β-glucans and mannanoligosaccharides) at 2.5 kg/tonne, and ImmunoWall (20% mannanoligosaccharide [MOS] and 35% β-1-3 glucans from S. cerevisiae) at 0.5 kg/tonne. Dietary inclusion level of each yeast product was chosen based on supplier recommendations specific to each product. Single-comb White Leghorn laying hens were moved to individual laying cages (n = 7 per treatment; starting at 40 wk of age) and randomly assigned to one of 5 experimental treatment groups. Hens were fed a standard wheat-based, commercial-type diet containing either no yeast product (control) or 1 of the 4 products. Initial and final (46 wk of age) body weights, overall feed intake, initial and final egg weights, initial and final shell quality (shell weight and shell thickness) and total egg production from 40 to 46 wk of age were determined for each hen.
Initial and final hen body weights, change in body weight, feed intake during the experiment, egg production, and egg weights were not affected by dietary treatment. The lack of a treatment effect suggests that, at least in the short term, there were no negative effects of any of the products on hen productivity. Although initial shell weight and shell thickness were similar among the treatment groups, hens fed Hilyses had lower shell weight and thickness at the end of the experiment (P = 0.004 and 0.026, respectively). Given the short duration of the trial, the small number of hens in the experiment, and the small numbers of eggs sampled, this could be an experimental artifact and may not reflect an actual decrease in shell quality.
The objective of this study was to conduct an initial comparison of commercial yeast products in layer hen diets on egg production parameters and the corresponding impact on the cecal microbiota. However, the commercial yeast products tested in this short trial had little effect on egg production and shell quality, and only moderately impacted the composition of mature layer hen cecal microbiota.