Impact of added copper, alone or in combination with chlortetracycline, on growth performance and antimicrobial resistance of fecal enterococci of weaned piglets.
J Anim Sci
; 98(3)2020 Mar 01.
Article
em En
| MEDLINE
| ID: mdl-31950170
ABSTRACT
Studies suggest a link between added copper (Cu) and co-selection of antimicrobial resistance (AMR) in Enterococcus spp., but data are inconsistent. This study aimed to assess the impact of added Cu, alone or with a feed-grade antimicrobial, on growth performance, transferable Cu resistance gene (tcrB) prevalence, abundance of tcrB in fecal community DNA, and AMR in fecal enterococci in weaned piglets. A total of 320 barrows (DNA 200â
×â
400, DNA Genetics) weaned at approximately 21 d of age with 7.4 kg (7.4â
±â
0.06 kg) BW were used in a 28-d study. Piglets were fed a common non-medicated diet for 7 d of acclimation. Treatments were arranged in a 2â
×â
2 factorial design with main effects of added Cu (0 vs. 200 mg/kg Cu from Cu sulfate) and chlortetracycline (0 vs. 440 mg/kg CTC). Growth performance and fecal samples were obtained on days 0, 14, and 28. There was no evidence (Pâ
>â
0.05) for Cu and CTC interaction in growth performance. Pigs fed diets with added Cu had increased (Pâ
<â
0.05) ADG and ADFI from days 0 to 14, with no evidence for differences (Pâ
>â
0.05) from days 15 to 28 and 0 to 28. Pigs fed diets with CTC had improved (Pâ
<â
0.01) ADG, ADFI, and GF from days 0 to 28. Prevalence of tcrB-positive enterococci was not affected by the addition of Cu and/or CTC (Pâ
>â
0.05). Prevalence of tcrB-positive enterococci was higher on day 14 than other sampling days (Pâ
=â
0.002). Prevalence of tetracycline resistance gene [tet(M)]-positive enterococci was not affected by treatments or day (Pâ
>â
0.05). Prevalence of macrolide resistance gene [erm(B)]-positive enterococci had a significant treatment and sampling day interaction (Pâ
=â
0.021). The abundance of the tcrB gene in feces, quantified by PCR, was not affected by Cu treatment. The median Cu minimum inhibitory concentrations (MIC) of tcrB-negative and -positive isolates were 3 and 20 mM, respectively (Pâ
<â
0.001). For day 0 and day 28, all Enterococcus isolates were susceptible to gentamicin, kanamycin, streptomycin, daptomycin, and tigecycline, with a majority of isolates resistant to chloramphenicol, erythromycin, lincomycin, linezolid, tetracycline, tylosin tartrate, and Synercid. In conclusion, 200 mg/kg added Cu or 440 mg/kg CTC in nursery diets improved growth performance of nursery pigs. Added Cu, with or without a selection pressure of CTC, did not increase Cu-resistant enterococci and did not co-select resistance to antibiotics.
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Base de dados:
MEDLINE
Assunto principal:
Suínos
/
Clortetraciclina
/
Enterococcus
/
Cobre
/
Fezes
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article