Dietary probiotic Lacticaseibacillus paracasei NSMJ56 modulates gut immunity and microbiota in laying hens.

This study was performed to investigate supplementary effects of probiotic Lacticaseibacillus paracasei NSMJ56 strain on laying performance, egg quality, intestinal histology, antioxidant status, gut immunity and microbiota in laying hens. A total of ninety-six 21-wk-old Hy-Line Brown laying hens were randomly subjected to one of 2 dietary treatments: a control group fed a non-supplemented diet, or a probiotic group fed with a diet supplemented with 1 g of Lacticaseibacillus paracasei NSMJ56 (5 × 108 CFU/kg of diet). The trial lasted for 4 wk. Egg weight was increased (P < 0.05) in laying hens fed probiotic-fed diet compared with the control group. Dietary probiotics did not affect egg quality except for Haugh unit, which was improved (P < 0.05) in the probiotic-fed group. Neither jejunal histology nor cecal short-chain fatty acids were affected by dietary treatments. Dietary probiotics increased the activity of catalase compared with the control group. Flow cytometry analysis revealed that dietary probiotics elevated the CD4+ T cells, but not CD8+ T cells, in jejunal lamina propria. Based on the LEfSe analysis at the phylum and genus levels, Erysipelotrichales, Erysipelotrichia, Flintibater, Dielma, Hespellia, Coprobacter, Roseburia, Anaerotignum, and Coprococcus were enriched in the probiotic group compared with the control group. Taken together, our study showed that dietary probiotics could be used to improve some parameters associated with egg freshness and antioxidant capacity, and to partially alter T cell population and microbial community in laying hens.

Effects of dietary protein levels on performance, nitrogen excretion, and odor emission of growing pullets and laying hens.

The objective of this study was to determine the effects of dietary crude protein (CP) levels on production performance, nitrogen balance, and odor emission of excreta in growing pullets and laying hens from 13 to 32 wk of age. Two hundred and forty pullets (Hy-Line Brown) were randomly assigned to 1 of 4 dietary groups with 10 replicates per group, and 6 birds per replicate. Experimental diets were formulated to contain 4 graded CP levels in the diets of pullets ranging from 180, 160, 140, and 120 g/kg of diet during 13 to 18 wk (phase 1) and in the diets of laying hens from 190, 170, 150, and 130 g/kg of diet during 19 to 32 wk (phase 2). The limiting amino acids including lysine, methionine, and threonine were supplemented to maintain constant equal amino acid concentrations in all experiment diets. In phase 1, decreasing dietary CP levels did not affect growth performance but increased (linear and quadratic effect, P < 0.05) the relative abdominal fat contents and triglyceride concentration in serum samples. High-density lipoprotein cholesterol in serum samples decreased as the CP levels decreased in the diets of pullets. Dietary CP levels quadratically increased (P < 0.05) the villus height and the villus height to crypt depth ratio but did not affect tibia traits and relative organ weights in pullets at 18 wk. Apparent digestibility of dry matter and ether extract increased with decreasing dietary CP levels in pullets. Graded CP levels linearly increased the digestibility of dry matter, CP, and ether extracts but lowered that of crude ash in laying hens. Nitrogen excretion was linearly decreased (P < 0.05) as the dietary CP levels decreased in both pullets and laying hens. Dietary CP levels only affected carbon dioxide emission in pullets. In phase 2, dietary CP levels did not affect growth performance and the ages at first egg laying and to reach 50% egg production in laying hens. However, egg weights were decreased (linear and quadratic effect, P < 0.05) as the dietary CP level decreased in laying hens. Increasing dietary CP levels increased Haugh unit at 26 wk but lowered corticosterone concentrations in yolk samples at 22 wk. Collectively, this study shows that dietary CP levels could be decreased to reduce nitrogen excretion without adverse effects on performance and egg quality of growing pullets and laying hens.