Objective: This study aimed to determine the effects of different roughages in total mixed ration (TMR) inoculated with or without coculture of Lactobacillus acidophilus (L. acidophilus) and Bacillus subtilis (B. subtilis) on in vitro rumen fermentation and microbial population.Methods: Three TMRs formulations composed of different forages were used and each TMR was grouped into two treatments: non-fermented TMR and fermented TMR (F-TMR) (inoculated with coculture of L. acidophilus and B. subtilis). After fermentation, the fermentation, chemical and microbial profile of the TMRs were determined. The treatments were used for in vitro rumen fermentation to determine total gas production, pH, ammonianitrogen (NH3-N), and volatile fatty acids (VFA). Microbial populations were determined by quantitative real-time polymerase chain reaction (PCR). All data were analyzed as a 3×2 factorial arrangement design using the MIXED procedure of Statistical Analysis Systems.Results: Changes in the fermentation (pH, lactate, acetate, propionate, and NH3-N) and chemical composition (moisture, crude protein, crude fiber, and ash) were observed. For in vitro rumen fermentation, lower rumen pH, higher acetate, propionate, and total VFA content were observed in the F-TMR group after 24 h incubation (p<0.05). F-TMR group had higher acetate concentration compared with the non-fermented group. Total VFA was highest (p<0.05) in F-TMR containing combined forage of domestic and imported source (F-CF) and F-TMR containing Italian ryegrass silage and corn silage (F-IRS-CS) than that of TMR diet containing oat, timothy, and alfalfa hay. The microbial population was not affected by the different TMR diets.Conclusion: The use of Italian ryegrass silage and corn silage, as well as the inoculation of coculture of L. acidophilus and B. subtilis, in the TMR caused changes in the pH, lactate and acetate concentrations, and chemical composition of experimental diets. In addition, F-TMR composed with Italian ryegrass silage and corn silage altered ruminal pH and VFA concentrations during in vitro rumen fermentation experiment.

This article describes the regulatory and evidence requirements necessary for the authorization of antimethanogenic feed additives (AMFA) aimed at mitigating enteric methane (CH₄) emissions from ruminants. It outlines the legislation and legal procedures in Australia, Canada, the European Union, New Zealand, South Korea, the United Kingdom, and the United States as illustrative examples, offering insights for applicants seeking authorization. Additionals objectives are to highlight consequential similarities and differences in regulations and evidence requirements and offer recommendations for scientists and applicants. The pivotal role that scientific evidence plays in the evaluation and approval processes is emphasized, along with the need for applicants and researchers to understand and adhere to the specific regulations of each jurisdiction. Feed additives are regulated to ensure their safety for animals, humans, and the environment, and to verify their effectiveness for the intended use of enteric CH₄ mitigation. Regulations cover various aspects, including ingredient safety, manufacturing practices, product labeling, and the establishment of permissible limits for certain substances to ensure their safe use in animal feed. Compliance with these regulations is mandatory, and they are enforced by regulatory agencies within each jurisdiction, aiming to protect animal health, promote food safety, and prevent misleading claims and unsafe practices. The assessment processes involve evaluating scientific evidence submitted by applicants, along with evaluations of quality control procedures, and record-keeping practices. The major difference in regulations is that each jurisdiction developed unique criteria to legally classify AMFA, making it challenging to satisfy all legal classifications with a single set of criteria for scientific evidence. However, numerous similarities and a universal reliance on the concept of intended use indicate consistency across all jurisdictions on the need for robust evidence for efficacy, safety, and product quality and documentation even if the type, size, duration, and location of the studies they require differ. Recommendations are made for both scientists and applicants, emphasizing the importance of designing, conducting, and reporting scientific evaluations transparently, using validated standards and methods, and communicating with regulatory bodies to ensure compliance with regulations and evidence requirements.

The effects of rumen buffer agents on ruminal fermentation parameters and bacterial community composition were determined using in vitro and in vivo experiments in three rumen-cannulated, high-concentrate fed Holstein Friesian dairy cows. Experiment 1 in vitro treatments included bentonite, calcium carbonate, calcium oxide, sodium bicarbonate, sodium sesquicarbonate, and processed coral, and unbuffered samples served as the control. Experiment 2 in vitro treatments were based on the formulation of various combinations of the buffer agents used in Experiment 1. Combinations were selected for the in vivo study based on their buffering ability. Calcium oxide, sodium bicarbonate, and sodium sesquicarbonate stabilized the ruminal pH and improved in vitro rumen fermentation. The combined buffer agents had a significant effect on pH, buffering capacity, total gas, and total volatile fatty acids. Firmicutes and Bacteroidetes were the dominant phyla in both treatments and the control. Ruminococcus and Prevotella were found to be the dominant genera. Ruminococcus bromii was predominant in the treatment group. Prevotella jejuni was more abundant in the control group compared to the treatment group, in which its abundance was very low. Ruminococcus flavefaciens and Intestinimonas butyriciproducens gradually increased in abundance as cows received treatment. Overall, a high-concentrate diet administered to cows induced adverse changes in ruminal pH; however, buffer supplementation enhanced ruminal fermentation characteristics and altered bacterial community, which could contribute to preventing ruminal acidosis.

The impact of soil with an intact microbial community and oxygen availability on moisture content, soil pH, and bacterial communities during decomposition of poultry carcasses was investigated. Poultry carcasses were decomposed in soil with or without a microbial community, under aerobic or anaerobic conditions. The samples collected in each microcosm burial set-up were analyzed by targeted 16S rRNA amplicon sequencing and Amplicon sequence variants (ASV) method. Our results showed that moisture was high in the burial set-ups under anaerobic conditions and pH was high in the burial set-ups under aerobic conditions. Meanwhile, the Chao1 and Shannon index significantly differed between the different burial set-ups and across different time points. In addition, bacterial taxa composition during the early period of decomposition differed from that of the late period. A total of 23 phyla, 901 genera, and 1992 species were identified. Firmicutes was the most dominant phyla in all burial set-ups throughout the decomposition. At day 60, Pseudogracilibacillus was dominant in the burial set-ups under aerobic conditions, while Lentibacillus dominated in the burial set-ups under anaerobic conditions. This study demonstrated that the soil microbial community and availability of oxygen significantly affected the changes in moisture content, pH, and bacterial composition during the decomposition process.

The objective of the present study was to identify changes in fecal microbiota and predict the functional features of healthy calves and those infected with rotavirus over time. Six Holstein calves (average body weight 43.63 ± 1.19 kg, age-matched within 5–7 d) were randomly selected and distributed into two groups which contained three calves each. Fecal samples were taken 3 days before inoculation and on days 1 and 7 post-inoculation. The 16S rRNA gene amplicon sequencing was performed. Bacterial diversity tended to decrease in the rota group, as indicated by the alpha (evenness, p = 0.074 and Shannon, p = 0.055) and beta (Bray–Curtis dissimilarity, p = 0.099) diversity at 1 day post-inoculation. Differences in the bacterial taxa between healthy and rota-infected calves were detected using a linear discriminant analysis effect size (LDA > 2.0, p < 0.05). Rota calves had a higher abundance of certain bacterial taxa, such as Enterococcus, Streptococcus, and Escherichia-Shigella, and a lower abundance of bacteria that contribute to the production of short-chain fatty acids, such as Alistipes, Faecalibacterium, Pseudoflavonifractor, Subdoligranulum, Alloprevotella, Butyricicoccus, and Ruminococcus, compared to the healthy calves. The observed changes in the fecal microbiota of the rota-infected group compared to the healthy group indicated potential dysbiosis. This was further supported by significant differences in the predicted functional metagenomic profiles of these microbial communities. We suggest that calves infected with bovine rotavirus had bacterial dysbiosis, which was characterized by lower diversity and fewer observed genera than the fecal microbiota of healthy calves.

Journal of Animal Science and Technology (JAST) is a peer-reviewed, open access journal publishing original research, review articles and notes in all fields of animal science. Topics covered by the journal include: genetics and breeding, physiology, nutrition of monogastric animals, nutrition of ruminants, animal products (milk, meat, eggs and their by-products) and their processing, grasslands and roughages, livestock environment, animal biotechnology, animal behavior and welfare.