Effects of micronized bamboo powder on performance, nutrient utilization, intestinal histology, and cecal microbiota...

Bamboo clum powder is an unconventional feed ingredient rich in insoluble dietary fiber, and its potential application and optimal inclusion level in laying hen diets remain unclear. This study was conducted to evaluate the effects of dietary supplementation with micronized bamboo powder (MBP) on laying performance, apparent nutrient digestibility, intestinal morphology, and cecal microbiota in late-laying hens, and to determine its appropriate inclusion level.

A total of 480 42-week-old Hy-Line Brown laying hens were randomly allocated into 4 groups with 5 replicates of 24 hens each. The trial hens were fed a basal diet (CON) or basal diets supplemented with 2% (TRE1), 3% (TRE2), or 4% (TRE3) MBP for 28 days following a 7-day adaptation period.

Compared with the CON group, the TRE3 group exhibited a significantly lower laying rate during days 15-28 and the overall experimental period of 1-28 d (p < 0.05), while no significant differences were observed between the TRE1, TRE2, and CON groups (p > 0.05). Moreover, the TRE3 group had significantly lower egg mass during days 15-28 and days 1-28 compared with the CON and TRE1 groups (p < 0.05). Treatments had no significant effect on serum triglyceride, total cholesterol, total protein or glucose levels (p > 0.05). The TRE3 group showed significantly lower apparent digestibility of dry matter, crude ash, crude protein, and gross energy compared to the CON group (p < 0.05). Intestinal histological analysis revealed that the TRE3 group had significantly greater duodenal and ileal wall thickness than the CON group (p < 0.05). Conversely, the TRE1 and TRE2 groups exhibited significantly higher jejunal villus height compared to the CON group (p < 0.05). 16S rRNA sequencing analysis of cecal microbiota indicated that dietary supplementation with MBP altered microbial diversity and composition. Specifically, the Sobs, Ace, and Chao indices were significantly lower in the TRE1 group than those in the CON group (p < 0.05). At the phylum level, the relative abundance of Actinobacteriota was significantly higher in the TRE1 and TRE3 groups that in the CON group (p < 0.05). At the genus level, the proportion of WPS-2 in the TRE2 group was significantly higher than that in the CON group (p < 0.05), while the proportion of Clostridia_UCG-014 in the TRE3 group was significantly lower than that in the CON group (p < 0.05). Correlation analysis further revealed that the abundances of Ruminococcus_torques_group and NK4A214_group (phylum Firmicutes) were significantly negatively correlated with daily feed intake, whereas Blautia showed a significant positive correlation with daily feed intake (p < 0.05). Moreover, the abundance of NK4A214_group was significantly negatively correlated with feed efficiency, while the abundance of Olsenella (phylum Actinobacteriota) was significantly positively correlated with feed efficiency (p < 0.05).

In conclusion, excessive supplementation of MBP (4%) led to thickened intestinal walls, decreased nutrient utilization, and reduced laying rate and egg mass in hens, which may be associated with a reduction in the abundance of beneficial cecal bacteria. Moderate MBP supplementation (2-3%) as a partial substitute for corn had no adverse effects on performance, despite some changes in digestibility and microbiota. This suggests that MBP has potential as an alternative feed ingredient for corn in laying hen diets, but its inclusion level requires careful consideration.