کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10973307 | 1108013 | 2016 | 10 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Control of Escherichia coli O157:H7 in contaminated alfalfa silage: Effects of silage additives
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کلمات کلیدی
موضوعات مرتبط
علوم زیستی و بیوفناوری
علوم کشاورزی و بیولوژیک
علوم دامی و جانورشناسی
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چکیده انگلیسی
This study was conducted to examine if adding microbial inoculants or propionic acid to alfalfa silages contaminated with Escherichia coli O157:H7 would inhibit the growth of the pathogen during or after ensiling. Alfalfa forage was harvested at the early bloom stage, wilted to a dry matter concentration of 54%, chopped to 19-mm lengths, and ensiled after treatment with one of the following: (1) distilled water (control); (2) 1Â ÃÂ 105 cfu/g of E. coli O157:H7 (EC); (3) EC and 1Â ÃÂ 106 cfu/g of Lactobacillus plantarum (EC+LP); (4) EC and 1Â ÃÂ 106 cfu/g of Lactobacillus buchneri (EC+LB); and (5) EC and 2.2Â g/kg of propionic acid (EC+PA). Each treatment was ensiled in quadruplicate in laboratory silos for 0, 3, 7, 16, and 100Â d and analyzed for EC counts, pH, and organic acids. In addition, samples from d 100 were analyzed for chemical composition, ammonia-N, counts of yeasts and molds, and aerobic stability. Escherichia coli O157:H7 was detected in all silages until d 7, but by d 16 it was not detected in those treated with EC+LB and EC+LP, though it was still detected in EC and EC+PA silages. However, by d 100, the pathogen was not detected in any silage. The rate of pH decrease to 5.0 was fastest for the EC+LP silage (7Â d), followed by the EC+LB silage (16Â d). Nevertheless, all silages had attained a pH of or less than 5.0 by d 100. The rapid decrease in pH in EC+LP and EC+LB silages was observed due to higher lactate and acetate concentrations, respectively, relative to the other silages during the early fermentation phase (d 3-16). Propionic acid was only detected in the EC+PA silage. Yeast counts were lowest in EC+LB and EC+PA silages. Subsamples of all d-100 silages were reinoculated with 1Â ÃÂ 105 cfu/g of EC immediately after silo opening. When the pathogen was subsequently enumerated after 168Â h of aerobic exposure, it was not detected in silages treated with EC+PA, EC+LB, or EC+LP, which all had pH values less than 5.0. Whereas the EC silage had a pH value of 5.4 and 2.3 log cfu/g of the pathogen. Certain bacterial inoculants can hasten the inhibition of E. coli O157:H7 during ensiling, such as propionic acid, and they can also prevent its growth on silage contaminated with the pathogen after ensiling.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Dairy Science - Volume 99, Issue 6, June 2016, Pages 4427-4436
Journal: Journal of Dairy Science - Volume 99, Issue 6, June 2016, Pages 4427-4436
نویسندگان
I.M. Ogunade, D.H. Kim, Y. Jiang, Z.G. Weinberg, K.C. Jeong, A.T. Adesogan,