Plastic pollution has become one of the major environmental problems facing human beings in the world today. Plastic waste accumulated in the environment forms plastic particles of different sizes due to farming activities, climate change, ultraviolet light, microbial degradation, and animal chewing. The pollution caused by microplastics has become a major environmental problem in recent years, and it is also a research hotspot in the field of ecological environment. More and more studies have found that ruminants are exposed to microplastics for a long time, which seriously threaten their healthy growth. This paper introduces the current situation of plastic pollution; the properties of microplastics and their effects on the ecological environment, human beings, and animals; summarizes the types and toxicity mechanisms of microplastics; and concludes the main ways that microplastics enter ruminants and their harm to them. In addition, the shortcomings and future development of microplastics in ruminants research are summarized and prospected to provide theoretical reference for the related research on alleviating the influence of microplastics on ruminant production.

This research evaluated the influence of lactic acid bacteria and cellulase, individually or in combination, on the quality of mixed amaranth and sweet potato vine silages. The experiment included four groups: control group with no additives addition (CG), added cellulase group (AS1), added lactic acid bacteria group (AS2) and combined supplementation group (AS3), with five replicates per group. The ensiling period lasted for 60 days. Parameters of silage, including chemical components, fermentation profile, aerobic stability, and in vitro nutrient digestibility, were determined. The results revealed that the quality of amaranth and sweet potato vine mixed silage was improved to a certain degree after addition of two additives individually. Combining these additives observably increased (p < 0.05) the lactic acid and crude protein contents and decreased the pH, ratio of ammonia nitrogen to total nitrogen and neutral detergent fiber content of mixed silage. Compared with the CG and AS1 groups, the number of lactic acid bacteria in the AS3 group increased significantly (p < 0.05), while aerobic bacteria and mold counts showed the opposite tendency. Also, the in vitro dry matter, crude protein and neutral detergent fiber digestibility of the AS3 group were higher (p < 0.05) than those of the CG group. Combined inoculation observably reduced (p < 0.05) the ammonia nitrogen concentration and increased (p < 0.05) the propionic and butyric acid concentrations of mixed silage under in vitro incubation. In summary, the inoculation of lactic acid bacteria and cellulase can enhance the fermentation profile and nutritional values of mixed silage made from amaranth and sweet potato vine, and the best improvement effects are obtained by the combined utilization of the two additives.

Given that suckling lambs with immature rumen development rely on intestinal microbiota for nutrient utilization, investigating the composition and functional characteristics of their intestinal microbiota is therefore of paramount importance. In this study, 16S rRNA gene amplicon sequencing technology was adopted to characterize and analyze the diversity and composition of the jejunum, ileum and cecum bacterial communities of lambs at 0, 7 and 28 days of age, and to predict the functions of the bacterial communities. The α-diversity analysis results revealed that in the jejunum of lambs, the Chao1, PD, Simpson and Shannon indexes differed significantly among the three age groups (p < 0.05). In the ileum, Shannon and Simpson indexes of the 0-days-of-age group were slightly lower than those of the 7 (8.84% and 12.66% reductions, respectively) and 28-days-of-age groups (19.34% and 15.85% reductions, respectively) (0.05 < p < 0.10). In the cecum, Simpson and Shannon indexes differed significantly (p < 0.05) among the three age groups. At the phylum level, Firmicutes (64.68%) and Proteobacteria (21.76%) dominated the bacterial communities across all intestinal segments, with a total of 42 phyla detected. At the genus level, 19 dominant genera were identified in the jejunum. Except for Bifidobacterium, which showed no significant age-related variation (p > 0.05), the relative abundance of the remaining 18 genera changed significantly with age (p < 0.05). In the ileum, compared with the 0-days-of-age group, the Lactobacillus abundance was significantly higher in the 7- and 28-days-of-age groups (p < 0.05), while the Escherichia-Shigella, Mannheimia and Enterobacter abundances were significantly reduced (p < 0.05). In the cecum, the genera, including Blautia, Sellimonas and Ruminococcaceae UCG-014, exhibited significant age-related differences (p < 0.05), whereas other genera showed no significant variation (p > 0.05). Collectively, the bacterial community α-diversity, compositional structure and specific genus abundance in the jejunum, ileum and cecum of lambs demonstrated pronounced age-dependent variation and intestinal segment specificity patterns. This study provides a foundation for a deeper understanding of the succession patterns of the early digestive tract microbiota in lambs, and is conducive to the development of early nutrition strategies based on precise regulation of the microbiome.

Fiber-degrading microorganisms are widely recognized for their potential to convert renewable lignocellulosic biomass into animal feed. However, translating this potential into practical application faces five critical yet underappreciated challenges. First, current screening methods, primarily including plate dilution and Congo red staining, are low-throughput, poorly reproducible and fail to capture the synergistic actions of natural microbial consortia. Second, the lack of standardized assays for quantifying cellulolytic activity compromises the reliability of cross-study comparisons. Third, safety assessments for fiber-degrading microorganisms remain superficial, with most studies neglecting mycotoxin production, antibiotic resistance gene transfer and long-term colonization risks. Fourth, fundamental differences between fungal and bacterial degradative systems, such as enzyme multiplicity, oxygen requirements and cellulosome assembly, are rarely considered in strain selection, leading to suboptimal application outcomes. Finally, the vast majority of positive in vitro degradation results fail to translate into improved animal performance in vivo, owing to poor microbial survival in the gastrointestinal tract, mismatched enzyme activity with gut pH and temperature, coupled with the absence of dose–response validation. This review critically evaluates these five bottlenecks across fiber-degrading microorganism types, screening platforms and practical livestock production applications. Overall, future progress should depend less on discovering “novel” strains and more on establishing standardized screening pipelines, rigorous safety frameworks and mechanistic understanding of in vivo efficacy, including direct head-to-head comparisons between fungal enzymes and bacterial probiotics under identical conditions.