AUTHOR=Azzaz Hossam H. , Kholif Ahmed E. , Murad Hussein A. , Vargas-Bello-Pérez Einar 

TITLE=A newly developed strain of Enterococcus faecium isolated from fresh dairy products to be used as a probiotic in lactating Holstein cows

JOURNAL=Frontiers in Veterinary Science

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.989606

DOI=10.3389/fvets.2022.989606

ISSN=2297-1769

ABSTRACT=<p>The objective of this study was to determine the ability of an isolated strain (EGY_NRC1) or commercial (NCIMB 11181) <italic>Enterococcus faecium</italic> as a probiotic for lactating cows. Two experiments were conducted: In Experiment 1, the effects of three levels (1, 2, and 3 g/kg diet, DM basis) of isolated and commercial <italic>E. faecium</italic> on <italic>in vitro</italic> ruminal fermentation kinetics, gas, methane (CH<sub>4</sub>) and nutrient degradability were determined. In Experiment 2, thirty multiparous Holstein cows (633 ± 25.4 kg body weight) with 7 days in milk, were randomly assigned to 3 treatments in a completely randomized design in a 60-day experiment. Cows were fed without any additives (control treatment) or supplemented with 2 g/kg feed daily of <italic>E. faecium</italic> EGY_NRC1 (contain 1.1 × 10<sup>9</sup> CFU/g) or commercial <italic>E. faecium</italic> NCIMB 11181 (contain 2 × 10<sup>12</sup> CFU/g). Diets were prepared to meet cow's nutrient requirements according to NRC recommendations. Probiotic doses were based on the <italic>in vitro</italic> Experiment 1. Feed intake, digestibility, blood parameters and lactation performance were evaluated. In Experiment 1, the isolated <italic>E. faecium</italic> linearly and quadratically increased (<italic>P</italic> &lt; 0.001) <italic>in vitro</italic> total gas production (TGP), the degradability of dry matter (dDM) and organic matter (dOM) while decreased (<italic>P</italic> &lt; 0.05) methane (CH<sub>4</sub>) percent of TGP, NH<sub>3</sub>CH<sub>4</sub> production, and pH. The commercial <italic>E. faecium</italic> increased TGP and decreased (<italic>P</italic> &lt; 0.01) CH<sub>4</sub> production, pH and increased the dDM and dOM, short chain fatty acids and ruminal NH<sub>3</sub>-N concentration. In Experiment 2, the isolated <italic>E. faecium</italic> increased (<italic>P</italic> &lt; 0.01) total tract digestibility of DM, neutral and acid detergent fiber, daily milk production and feed efficiency compared to the control treatment without affecting feed intake and milk composition. Moreover, the isolated <italic>E. faecium</italic> increased (<italic>P</italic> &lt; 0.05) the proportion of C18:1 <italic>trans</italic>-9, C18:2 <italic>cis</italic>-9-12 and C18:2 <italic>trans</italic>-10 <italic>cis</italic>-12. Both isolated and commercial <italic>E. faecium</italic> improved (<italic>P</italic> &lt; 0.01) organic matter, crude protein and nonstructural carbohydrates digestibility, increased serum glucose (<italic>P</italic> = 0.002) and decreased serum cholesterol (<italic>P</italic> = 0.002). Additionally, both <italic>E. faecium</italic> strains decreased C23:0 (<italic>P</italic> = 0.005) in milk. In conclusion, the use of <italic>E. faecium</italic> (isolated and commercial) at 2 g/kg DM of feed improved feed efficiency and production performance, with superior effects on animal performance from isolated <italic>E. faecium</italic> compared to the commercial one.</p>