Live coccidiosis vaccines have mainly been used to reduce Eimeria species infection, which is considered the most economically important disease in the poultry industry. Evaluation data on vaccine effectiveness through large-scale field experiments are lacking, especially in broilers. Thus, the effectiveness of a commercial coccidiosis vaccine was evaluated in approximately 900,000 chicks reared on three open-broiler farms where coccidiosis is prevalent. The vaccine’s effectiveness after vaccination of 1-day-old chicks was monitored using three parameters (lesion score, fecal oocyst shedding, and production index, PI) in nine trials performed three times on each farm. Lesion scores were confirmed in three different areas of the intestine because the vaccine contained four Eimeria species. The average lesion scores were 0.36 to 0.64 in the duodenal region, 0.30 to 0.39 in the jejuno-ileal region, and 0.18 to 0.39 in the cecal region. The average fecal oocyst shedding rate ranged from 19,766 to 100,100 oocysts per gram, showing large variations depending on farms and buildings within the farm. Compared with the PI of the previous 9–10 trials on each farm, the PI increased by 2.45 to 23.55. Because of the potential for perturbation of the fecal microbiota by live coccidiosis vaccines, the fecal microbiota was investigated using 16S rRNA microbial profiling. Although the β-diversity was significantly different in distribution and relative abundance among farms (PERMANOVA, pseudo-F = 4.863, p = 0.009), a Kyoto Encyclopedia of Genes and Genomes pathway analysis found no significant bacterial invasion of the epithelial cell pathway across farms. This large-scale field trial of a live Eimeria vaccine indicates that coccidiosis vaccines can have meaningful effects on the poultry industry and could be used as an alternative to the prophylactic use of anticoccidial drugs under field conditions.

Protaetia brevitarsis larvae are farm-raised for food, are used in traditional East Asian medicine, and convert organic waste into biofertilizers. Here, the comparative analysis of the gut microbiota of third-instar larvae obtained from five different farms was investigated using 16S rRNA microbial profiling. Species richness, evenness, and diversity results using α-diversity analysis (observed species, Chao1, Shannon, Simpson) were similar between farms, except for those between the TO and KO farms. β-diversity was significantly different in distribution and relative abundance between farms (PERMANOVA, pseudo-F = 13.20, p = 0.001). At the phylum level, Bacillota, Bacteroidota, Actinomycetota, and Pseudomonadota were the most dominant, accounting for 73–88% of the hindgut microbial community. At the genus level, Tuberibacillus, Proteiniphilum, Desulfovibrio, Luoshenia, and Thermoactinomyces were the most abundant. Although oak sawdust was the main feed component, there were large variations in distribution and relative abundance across farms at the phylum and genus levels. Venn diagram and linear discriminant analysis effect size analyses revealed large variations in the hindgut microbial communities of P. brevitarsis larvae between farms. These results suggest environmental factors were more important than feed ingredients or genetic predisposition for the establishment of the intestinal microbiota of P. brevitarsis larvae. These findings serve as reference data to understand the intestinal microbiota of P. brevitarsis larvae.

The scarab species Protaetia brevitarsis, an edible insect, has been used in traditional medicine, as animal feed, and for converting agricultural organic wastes into biofertilizer. The intestinal tract, which contains a diverse array of microbiota, including viruses, plays a critical role in animal health and homeostasis. We previously conducted a comparative analysis of the gut microbiota of third-instar larvae of P. brevitarsis obtained from five different farms and found significant differences in the composition of the gut bacterial microbiota between farms. To better understand the gut microbiota, the composition of DNA viruses in the hindgut contents of P. brevitarsis larvae obtained from five farms was investigated using metagenomic sequencing in this study. The β-diversity was significantly different between metagenomic data obtained from the five farms (PERMANOVA, pseudo-F = 46.95, p = 0.002). Family-based taxonomic analysis indicated that the relative abundance of viruses in the gut overall metagenome varied significantly between farms, with viral reads comprising approximately 41.2%, 15.0%, 4.3%, 4.0%, and 1.6% of metagenomic sequences from the farms Tohamsan gumbengi farm (TO), Secomnalagum gumbengi (IS), Gumbengi brothers (BR), Kyungpook farm (KB), and Jhbio (JH), respectively. More than 98% of the DNA viruses in the hindgut were bacteriophages, mainly belonging to the Siphoviridae family. At the species level, Phage Min1, infecting the genus Microbacterium, was detected in all farms, and it was the most abundant bacteriophage in intestinal microbiota, with a prevalence of 0.9% to 29.09%. The detected eukaryotic DNA viruses accounted for 0.01% to 0.06% of the intestinal microbiota and showed little or no relationship with insect viruses. Therefore, they most likely originated from contaminated feed or soil. These results suggest that the condition of substrates used as feed is more important than genetic factors in shaping the intestinal viral microbiota of P. brevitarsis larvae. These results can be used as reference data for understanding the hindgut microbiota of P. brevitarsis larvae and, more generally, the gut virome of insects.