Fermented soybean meal affects the ruminal fermentation and the abundance of selected bacterial species in Holstein calves: a multilevel analysis.

The effect of soybean meal (SBM) replacement with fermented SBM (FSBM) on ruminal fermentation and bacterial abundance in Holstein calves was investigated in this study. Thirty nine calves were randomized to: (1) control: 27% SBM + 0% FSBM (FSBM0, n = 13); (2) 18% SBM + 9% FSBM (FSBM9, n = 13); and (3) 13.5% SBM + 13.5% FSBM (FSBM13, n = 13). SBM contained a greater amount of large peptides containing 3 to 10 amino acids (AAs), while FSBM had a greater amount of ammonia nitrogen (NH3-N), free AAs, and small peptides containing 2 to 3 AAs. The calves fed FSBM13 had the lowest acetic acid, NH3-N, and the ratio of acetate to propionate, with the greatest concentration of caproic acid, valeric acid and isovaleric acid in ruminal fluid. Compared to those fed FSBM9 or FSBM13, the calves fed FSBM0 had the greatest proportion of Butyrivibrio fibrisolvens and Ruminococcus albus in rumen fluid. However, the ruminal abundance of Prevotella ruminicola in calves fed FSBM13 was greater than in calves fed FSBM0. Network analysis showed that the abundance of the Ruminococcus albus was associated with large peptides, and butyric acid was correlated with small peptide. Taken together, our findings suggest that FSBM may have the potential to boost calf performance by changing the fermentation products and the relative abundance of some members of the bacterial community in the rumen.

Green ultrasound assisted magnetic nanofluid-based liquid phase microextraction coupled with gas chromatography-mass spectrometry for determination of permethrin, deltamethrin, and cypermethrin residues.

Ultrasound-assisted magnetic nanofluid-based liquid-phase microextraction was coupled to GC-MS in a method for simultaneous determination of the pyrethroid insecticides permethrin, deltamethrin, and cypermethrin. A highly efficient extraction solvent called "magnetic nanofluid (MNF)" is introduced for preconcentration of pyrethroids. The MNF consists of magnetic multiwalled carbon nanotubes (MMWCNTs) and deep eutectic solvent. Following microextraction, the MNF was detached by an external magnet from the medium without the need for centrifugation. 2-Pyridinecarboxamide, choline chloride, and anhydrous ferric chloride were used for the synthesis of the deep eutectic solvent. The effects of pH value, volume of MNF, sonication time, sample volume, and ionic strength, type and amount of back extraction solvent were investigated. Under optimum conditions of MNF volume of 50 µL, time of 5 min, 100 µL acetone as back extraction solvent, NaCl concentration of 1 mol.L-1 and sample volume of 30 mL, the detection limits are 2.8, 2.7 and 2.0 ng·mL-1 for permethrin, deltamethrin and cypermethrin, respectively. The linear response ranges are between 0.01 and 250 ng·mL-1, and relative standard deviations (for n = 7) are 3.5, 3.2 and 2.8%. The method was successfully applied to the determination of trace levels of permethrin, deltamethrin and cypermethrin in (spiked) milk samples. Graphical abstract Schematic representation of ultrasound assisted magnetic nanofluid-based liquid phase microextraction separation/preconcentration of permethrin, deltametrin, and cypermethrin residues in milk using GC-MS.