Fermented calcium butyrate supplementation in post-peak laying hens improved ovarian function and tibia quality through the“gut-bone”axis

The compromised egg quality and leg abnormality during the end of the laying cycle(after 40 weeks)have been leading to poor animal welfare and substantial economic losses.Therefore,the effects of fermented calcium(Ca)butyrate,produced by fermentation by Clostridium butyricum,on production,eggshell quality,and tibial property of hens were explored.A total of 192 Hy-line brown laying hens at50-week-old were assigned to a basal diet or the basal diet with 300 mg/kg of the fermented Ca butyrate from 50 to 58 weeks of age.Each treatment had 6 replicates with 16 hens each.The diet supplemented with 300 mg/kg fermented Ca butyrate notably increased egg weight,ovarian follicle number,and eggshell strength(P=0.072)as compared to the basal diet,which were associated with cytokine secretion,toll-like receptor signaling pathways,and intestinal immunity based on the RNA-seq data from the granulosa.Dietary Ca butyrate inclusion decreased the expression of ileal tumor necrosis factor-alpha and serum pro-inflammatory cytokine concentration,as well as increased the content of serum immunoglobulin A when compared to the basal diet(both P<0.05).The birds that received fermented Ca butyrate diets exhibited higher villus height(P<0.05)and upregulated expression of tight junction proteins,whereas it did not alter the composition of cecal microbiota(P>0.05).In addition,the diet with fermented Ca butyrate reduced the number of osteoclasts in the proximal tibia and the level of C-terminal cross-linked telopeptide of type I collagen,a bone resorption marker(P<0.05),whereas it tended to increase the concentration of the procollagen type I N-terminal propeptide that reflects bone formation marker in serum.Moreover,the layers fed fermented Ca butyrate diets possessed higher(P<0.05)bone area and trabecular number of the proximal tibia,yield load,and ultimate load than those that consumed basal diets.Collectively,dietary fermented Ca butyrate supplementation in post-peak layer diets improved the ovarian function and tibia quality,which might be related to enhancing intestinal integrity and consequently decreasing inflammation mediated bone resorption.

Continuous biohydrogen production from diluted molasses in an anaerobic contact reactor

An anaerobic contact reactor (ACR) systemcomprising a continuous flow stirred tank reactor (CSTR)with settler to decouple the hydraulic retention time(HRT) from solids retention time (SRT) was developedfor fermentative hydrogen production from dilutedmolasses by mixed microbial cultures. The ACR wasoperated at various volumetric loading rates (VLRs) of20-44 kgCOD·m^(-3)·d^(-1) with constant HRT of 6 h undermesophilic conditions of 35°C. The SRTwas maintained atabout 46-50 h in the system. At the initial VLR of20 kgCOD·m^(-3)·d^(-1), the hydrogen production rate droppedfrom 22.6 to 1.58 L·d^(-1) as the hydrogen was consumed bythe hydrogentrophic methanogen. After increasing theVLR to 28 kgCOD·m^(-3)·d^(-1) and discharging the sludge for6 consecutive times, the hydrogentrophic methanogenswere eliminated, and the hydrogen content reached 36.4%.As the VLR was increased to 44 kgCOD·m^(-3)·d^(-1), thehydrogen production rate and hydrogen yield increased to42.1 L·d^(-1) and 1.40 mol H2·molglucose-consumed^(-1),respectively. The results showed that a stable ethanoltypefermentation that favored hydrogen production inthe reactor was thus established with the sludgeloading rate (SLR) of 2.0-2.5 kgCOD·kgMLVSS-1·d^(-1).It was found that the ethanol increased more than otherliquid fermentation products, and the ethanol/acetic acid(mol/mol) ratio increased from 1.27 to 2.45 when the VLRincreased from 28 to 44 kgCOD·m^(-3)·d^(-1), whereas thehydrogen composition decreased from 40.4% to 36.4%.The results suggested that the anaerobic contact reactorwas a promising bioprocess for fermentative hydrogenproduction.