# Effects of Probiotic Lacticaseibacillus paracasei NSMJ27 on Laying Performance and Gut Health Indicators in Aged Laying Hens

## TL;DR

This study shows that adding a probiotic strain from Korean kimchi improves gut health in older laying hens without affecting egg production.

## Contribution

The novel contribution is the in vivo validation of Lacticaseibacillus paracasei NSMJ27's probiotic effects in aged laying hens.

## Key findings

- L. paracasei NSMJ27 increased gut antioxidant capacity in laying hens.
- The probiotic elevated cecal butyrate levels and tended to improve villus height: crypt depth ratio.
- Egg production and quality were unaffected by the probiotic supplementation.

## Abstract

Probiotics are live beneficial microbes that are known to improve the performance, health and welfare of laying hens. In our attempts to develop novel probiotic strains for poultry, Lacticaseibacillus paracasei NSMJ27, isolated from Korean fermented foods, gained our attention for its probiotic potential. It is known that dietary probiotic strains, although they exert beneficial potentials in vitro, require in vivo validation with chickens to verify biological effectiveness. In the present research, we attempted to evaluate the effect of a novel probiotic strain on gut health in aged laying hens. Our study shows that L. paracasei NSMJ27 enhanced antioxidant capacity and improved gut health, suggesting its potential use as a feed additive for laying hens.

This experiment was designed to determine the effect of the Lacticaseibacillus paracasei (paracasei) strain NSMJ27, isolated from Korean fermented vegetable food (home-made kimchi), on laying performance, egg quality, intestinal histology, cecal short-chain fatty acids, and ileal antioxidant/immunity indicators of laying hens. Ninety-six 55-week-old Hy-Line Brown hens were randomly assigned to two dietary treatments with each treatment comprising eight replicates of six hens each. Experimental diets were prepared by mixing corn and soybean meal basal diets without or with L. paracasei NSMJ27 at 2.5 × 109 CFU/kg. The experiment lasted 4 weeks. Laying hens fed with the NSMJ27-supplemented diet were not affected (p > 0.05) in their laying performance or egg quality. With respect to ileal morphology, villus height: crypt depth ratio tended to be higher (p = 0.067) in laying hens fed with L. paracasei NSMJ27 vs. control diets. Dietary L. paracasei did not affect (p > 0.05) the activities of glutathione peroxidase and catalase, malondialdehyde contents, or secretory immunoglobulin A in ileal mucosa, but increased (p = 0.048) the activity of superoxide dismutase compared with the control diet-fed laying hens. Dietary L. paracasei elevated (p = 0.016) the relative percentage of butyrate but lowered (p = 0.057) that of isovalerate in cecal digesta. Dietary L. paracasei did not affect the percentages of cells expressing macrophages, B cells, CD4+ T cells, CD8+ T cells, or TCRγδ T cell surface markers (p > 0.05). Overall, these results suggest that dietary L. paracasei NSMJ27 could enhance gut health via increasing gut antioxidant capacity and butyrate production in the cecal digesta of laying hens.