Chenxi Dong

This study examined the effects of purified lovastatin (LV) obtained from Monascus fermentation on ruminal fermentation, methane production, and microbial communities during a 48-h in vitro incubation. A fattening-sheep diet containing concentrate and roughage at 60:40 was treated with 0, 50, 100, or 150 mg LV/kg dry matter (DM). Samples from the control and 100 mg/kg DM treatments were selected for bacterial and archaeal 16S rRNA amplicon sequencing. Compared with the control, supplementation with 100 mg LV/kg DM significantly decreased methane production (mL/g DM) and methane content (%) by 22.1% and 12.7%, respectively, while increasing in vitro DM degradation by 4.9%. Cumulative gas production and total VFA concentration did not differ significantly among treatments. The molar proportion of propionate was higher at 150 mg/kg DM, while MCP concentration was higher at 100 mg/kg DM. Rikenellaceae RC9 gut group, Eubacterium, Succinivibrionaceae UCG-001, and Anaerovibrio were enriched in the LV treatment, whereas Methanococcus and Methanosphaera were enriched in the control. These results demonstrate the potential of lovastatin as a natural inhibitor of ruminal methanogenesis, with 100 mg/kg DM showing the greatest efficacy among the doses tested under the present in vitro conditions.

Grain byproducts can serve as cost-effective alternatives to corn, but may lead to reduced production performance and increased greenhouse gas emissions. This study aimed to investigate the effects of replacing corn with the grain byproducts (wheat bran, sprayed corn bran) subjected to bacterial-enzymatic fermentation treatment or not in Hu sheep, mainly focusing on production performance, energy-nitrogen metabolism, rumen fermentation and greenhouse gas emissions. A total of fifty-four 6-month-old Hu sheep were divided into three groups, with 6 pens per group and 3 sheep per pen, and then randomly allocated to one of the three dietary groups for 60 days, i.e., a control group (CON), a group (RC) that corn was partially (~42%) replaced with grain byproducts, and a group (BF) that corn was partially replaced by fermented grain byproducts. Compared with the CON group, the RC group showed numerically lower rumen total volatile fatty acid (TVFA) concentration and its propionate proportion, nitrogen retention content (NR; −10.22%) and its retention ratio (NR/NI decreased by 4.27 percentage points, absolute reduction from 24.30% to 20.04%), corresponding to a relative decrease of 17.6%.) as well as a numerically reduced net profit (−2.18%) with a decreased feed price (−¥0.16/kg TMR). Meanwhile, the RC group showed a significant increase in the relative abundance of Methanobrevibacter (p < 0.05), accompanied by numerically higher daily methane emissions (+6.14%) and emission intensity (+4.08%), although these methane-related differences did not reach statistical significance (p > 0.05). Compared to the RC group, the BF group resulted in a numerical increase in feed price (+¥0.03/kg TMR), net profit (+27.93%), TVFA concentration, propionate proportion, NR (+28.17%), NR/NI (an increase of 5.38 percentage points), the relative abundance of Prevotella, Shuttleworthia and Succinivibrio as well as the decrease of fecal nitrogen (FN; −12.29%), daily methane emissions (−8.75%), emission intensity (−5.83%) and the relative abundance of Methanobrevibacter. In summary, replacing dietary corn by 42% with wheat bran and sprayed corn bran numerically reduced formula cost and nitrogen utilization, while increasing methane emissions and methanogens abundance, without significantly affecting growth performance. This combination led to no improvement in economic returns for fattening Hu sheep. Bacterial-enzymatic fermentation treatment of these byproducts could mitigate these drawbacks, being superior energy-nitrogen metabolism and lower greenhouse gas emissions intensity, presenting a potential strategy for cost reduction and efficiency enhancement. Further research with larger sample sizes is warranted to confirm these findings and support broader application.

To investigate the effect of phenyllactic acid (PLA) on the dynamic changes of high-moisture stylo silage, fresh stylo was ensiled with addition of PLA at the levels of 0, 1% and 2% using lab-level silage bags, where samples were collected on days 3, 7, 14 and 30 of ensiling fermentation to analyze fermentation parameters, nitrogen distribution and bacterial community. The results showed that PLA addition at ensiling led to the increase (p < 0.01) in dry matter content, lactic acid concentration and Flieg’s score of stylo silage as well as the decrease (p < 0.01) in dry matter loss, pH value and coliform bacteria population, with butyric acid only detected in the control group. It also resulted in the increase (p < 0.01) in true protein content and its proportion as well as the decrease (p < 0.01) in ammonia-N content and its proportion, almost with linearly dose effect. Sequencing analysis revealed that PLA addition led to the increase (p < 0.05) in Sobs, Shannon, Chao and Ace of bacterial community in the stylo silage, where the relative abundance of Enterobacter, Clostridium, and Kosakonia was decreased, and that of Lactobacillus, Enterococcus and Pantoea was increased. Furthermore, Kosakonia, Terriglobus, Sphingomonas and Sphingopyxis had an important role in the bacterial interaction network. It is suggested that PLA application at the level of 1–2% could improve silage quality of stylo silage via modifying bacterial community.