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Simple Summary: Comparative analysis of the gut microbiota in wild grazing (WG) and domestic grazing (DG) yaks reveals distinct differences in bacterial diversity, with WG animals exhibiting a higher diversity than DG animals. Firmicutes dominate both groups, with a greater abundance in the WG type, indicating a stronger fiber-degrading capacity. WG yaks have a higher abundance of Ruminococcaceae and Rikenellaceae families, which are known for their role in fiber degradation, and genus-level differences show a greater presence of fiber-degrading microbes, such as Ruminococcus and Rikenella. In contrast, DG yaks have a higher abundance of Prevotellaceae, Alloprevotella, and Succinivibrio, associated with protein and carbohydrate degradation, reflecting their different dietary habits. These differences in gut microbiota composition suggest that feeding patterns are crucial in shaping the microbial community, influencing yak health and environmental adaptation. The findings presented herein have significant implications for livestock production, highlighting the importance of considering the impact of grazing practices on gut microbiota, and providing valuable insights for developing prebiotics and microbiological agents tailored to specific dietary needs. The gut microbiota is a diverse and complex population, and it has a key role in the host's health and adaptability to the environment. The present study investigated the fecal bacterial community of wild grazing (WG) and domestic grazing (DG) yaks on natural grazing pastures, analyzing the gut microbiota using 16S rRNA sequencing to assess bacterial diversity. A total of 48 yak fecal samples were selected from two different grazing habitats. The DG group had more crude proteins and non-fiber carbohydrates. The WG group had more OM, insoluble dietary fiber such as NDF, ADF, ether extract, and TC. There were 165 and 142 unique operational taxonomic units (OTUs) in the WG and DG groups, respectively. Shannon index analysis revealed a higher bacterial diversity in the WG group than in the DG group. At the phylum level, Firmicutes were the dominant bacterial taxa in both groups. The relative abundance of Firmicutes in the WG group was higher than in the DG group. At the family level, the WG group had a significantly higher abundance of Ruminococcaceae (p < 0.001) and Rikenellaceae (p < 0.001) than the DG group. The abundances of Alloprevotella and Succinivibrio were more pronounced in the DG group than in the WG group at the genus level. This study presents a novel understanding of the bacterial communities of ruminants and their potential applications for livestock production. [ABSTRACT FROM AUTHOR]

Simple Summary: Developing alternative antibiotics is crucial for sustainable animal production worldwide. Bacteriocin has been considered a potential alternative to antibiotics due to its lack of drug resistance, lack of residues, and environmental friendliness. In this study, we investigated the effects of inoculating two bacteriocin-producing strains, Lactiplantibacillus plantarum ATCC14917 and LP1-4, at ensiling on the in vitro ruminal fermentation characteristics and methane emissions of alfalfa silage with two different dry matter contents (355 g/kg fresh weight, moderate dry-matter content; 428 g/kg fresh weight, high dry-matter content). The results showed that inoculating with ATCC14917 and LP1-4 at ensiling reduced in vitro rumen methane production and enhanced the dry matter digestibility of ensiled alfalfa. Therefore, bacteriocin-producing L. plantarum ATCC14917 and LP1-4 inoculants can potentially mitigate ruminal methane emissions but without an adverse effect on the rumen fermentation of the inoculated alfalfa silage. The objective of this study was to investigate the effects of inoculating two bacteriocin-producing strains, Lactiplantibacillus plantarum ATCC14917 and LP1-4, at ensiling on the in vitro ruminal fermentation characteristics and methane production of alfalfa silage with two dry matter (DM)contents. Before ensiling, fresh alfalfa was wilted to a moderate DM content (355 g/kg) and a high DM content (428 g/kg). The wilted alfalfa was treated with (1) distilled water (control), (2) commercial strain L. plantarum MTD/1 (MTD/1), (3) bacteriocin-producing L. plantarum ATCC14917 (ATCC14917), and (4) a bacteriocin-like substance producing L. plantarum LP1-4 (LP1-4) at 1 × 105 colony forming units (CFU)/g fresh weight. After 90 d of ensiling, the silages were used for in vitro rumen fermentation. Inoculation with the two bacteriocin-producing strains at ensiling remarkably reduced (p < 0.05) in vitro ruminal CH4 production and enhanced DM digestibility compared with the control group regardless of DM content. For silages with high DM content, inoculation with the bacteriocin-producing strains even increased (p < 0.05) in vitro ruminal total volatile fatty acid production. Therefore, the bacteriocin-producing inoculants have a great potential to mitigate ruminal methane emission but without an adverse effect on rumen fermentation of the inoculated alfalfa silage. [ABSTRACT FROM AUTHOR]

Simple Summary: Bacteriocins produced by lactic acid bacteria are considered good alternatives for feed antibiotics because of inhibiting spoilage microorganisms in silage and non-drug resistance in animals. Owing to the narrow antibacterial spectrum, class I bacteriocin-producing lactic acid bacteria are considered to have limitations as silage inoculants. The research was conducted to evaluate the effects of two class IIa bacteriocin-producing Lactobacillus on silage fermentation, microbial population, chemical composition, and aerobic stability. The strains results showed that class IIa bacteriocin-producing lactic acid bacteria could improve silage fermentation quality, reduce counts of molds and yeasts, and improve aerobic stability to a greater extent than inoculation with Lactobacillus plantarum MTD/1, a proven, widely used inoculant, which does not produce bacteriocin. The findings of this research are of great value for current understandings and onwards to conduct further research and for possible practical implementation of class IIa bacteriocin-producing lactic acid bacteria as silage inoculants. The effects of two strains of class IIa bacteriocin-producing lactic acid bacteria, Lactobacillus delbrueckii F17 and Lactobacillus plantarum (BNCC 336943), or a non-bacteriocin Lactobacillus plantarum MTD/1 (NCIMB 40027), on fermentation quality, microbial counts, and aerobic stability of alfalfa silage were investigated. Alfalfa was harvested at the initial flowering stage, wilted to a dry matter concentration of approximately 32%, and chopped to 1 to 2 cm length. Chopped samples were treated with nothing (control, CON), Lactobacillus delbrueckii F17 (F17), Lactobacillus plantarum (BNCC 336943) (LPB), or Lactobacillus plantarum MTD/1 (NCIMB 40027) (LPN), each at an application rate of 1 × 106 colony-forming units/g of fresh weight. Each treatment was ensiled in quadruplicate in vacuum-sealed polyethylene bags packed with 500 g of fresh alfalfa per bag and ensiled at ambient temperature (25 ± 2 °C) for 3, 7, 14, 30, and 60 days. The samples were then subjected to an aerobic stability test after 60 days of ensiling. Compared with the CON silage, the inoculants reduced the pH after 14 days of ensiling. After 60 days, pH was lowest in the LPB-treated silage, followed by the F17 and LPN-treated silages. Inoculation of F17 increased concentrations of lactic acid in silages fermented for 7, 14, 30, and 60 days relative to other treatments, except for the LPN-treated silages ensiled for 30 and 60 days, in which the lactic acid concentrations were similar to that of F17 silage. Application of F17 and LPB decreased the number of yeast and mold relative to CON and LPN-treated silages. Compared with the CON silage, inoculant-treated silages had greater aerobic stability, water-soluble carbohydrate, and crude protein concentrations, and lower neutral detergent fiber, amino acid nitrogen, and ammonia nitrogen concentrations. The LPB-treated silage had the greatest aerobic stability followed by the F17-treated silage. Both class IIa bacteriocin producing inoculants improved alfalfa silage fermentation quality, reduced the growth of yeasts and molds, and improved the aerobic stability of the ensiled forage to a greater extent than the proven LPN inoculant. However, higher crude protein concentration and lower ammonia nitrogen concentration were observed in LPN-treated silage relative to other treatments. [ABSTRACT FROM AUTHOR]

Simple Summary: Cow variability present in nutrient digestibility studies differs for different diets and nutrients. It is a major factor determining adequate sample size so that studies are not under-powered or over-powered. The objective of the current study was to develop cow variability estimates that can be used to determine the optimal sample size for digestibility trials having randomized block designs using mid-lactation dairy cows when fed corn-based diets having different neutral detergent fiber:starch ratio (0.7, 1.0, and 1.3). Cow variability is greater for digestibility of fiber and dry matter and less for starch. Estimated cow variability as standard deviations for digestibility of dry matter, neutral detergent fiber and starch were 3.8 g/kg, 5.1 g/kg and 3.3 g/kg, respectively. A major implication of this study is that cow variability is greatest for fiber digestibility and the use of a minimum of 12 cows per dietary treatment is adequate to reliably detect treatment effects on the digestibility of fiber, starch and dry matter using lactating dairy cows fed in groups with randomized block design under current experimental conditions. The objective of this study was to estimate cow variability that can be used to determine the optimal sample size for digestibility trials using lactating dairy cows. Experimental design was randomized complete block design having three blocks and three dietary treatments. Three similarly managed nearby intensive farms were considered as blocks, and three diets were formulated to have 0.7, 1.0, and 1.3 neutral detergent fiber (NDF): starch ratio. In each farm, 18 cows were assigned for each dietary treatment and five sample sizes per each treatment group were simulated by simple random sampling of data from 18, 15, 12, 9 and 6 cows respectively. Intake was not affected by diet or sample size (p > 0.05). Estimated cow variability (as standard deviation) for digestibility of dry matter, NDF and starch were 3.8 g/kg, 5.1 g/kg and 3.3 g/kg, respectively. A major implication of this study is that cow variability is greatest for NDF digestibility and the use of a minimum of 12 cows per dietary treatment is adequate to reliably detect treatment effects on the digestibility of NDF, starch and dry matter using cows fed in groups with randomized block design under these experimental conditions. [ABSTRACT FROM AUTHOR]