Antimicrobial Use in Canadian Cow–Calf Herds

Abstract

Despite growing concern surrounding antimicrobial use (AMU) and the importance of cow–calf herds to the Canadian livestock industry, surveillance of AMU in cow–calf herds to inform antimicrobial stewardship programs has been sporadic. Producers from the Canadian Cow–Calf Surveillance Network (87%, 146/168) provided data and almost all reported AMU in at least one animal (99%, 145/146 herds) in 2019–2020. The most common reasons for AMU were treatment of respiratory disease in nursing calves in 78% of herds and neonatal diarrhea in 67% of herds, as well as for lameness in cows in 83% of herds. However, most herds treated <5% of animals for these reasons. Less than 2.5% of herds treated more than 30% of calves for either bovine respiratory disease or neonatal diarrhea and no herds treated more than 30% of cows for lameness. The most frequently reported antimicrobial was oxytetracycline in 81% of herds, followed by florfenicol in 73% of herds. Antimicrobials with very high importance to human health, such as ceftiofur, were used at least once by 20% of herds but were only used in >30% of nursing calves from one herd. Similarly, while 56% of herds used macrolides at least once, within-herd use was the highest in nursing calves where <4% of herds reported use in >30% of animals. Herds using artificial insemination and calving in the winter were more likely (p = 0.05) to treat >5% of nursing calves for respiratory disease, suggesting the importance of vaccination programs for herds at risk. Overall, AMU was similar to previous Canadian studies; however, the percentage of herds using macrolides had increased from a comparable study in 2014.

The Canadian Cow-Calf Surveillance Network – productivity and health summary 2018 to 2022

“…The C3SN is also the first pan-Canadian study to collect longitudinal data on treatment for the most commonly reported calfhood diseases and reasons for AMU, in addition to death loss in cow-calf herds for both the first month of life and for the period from birth to weaning ( 26 ). Differences in treatments between cows and heifers were not requested due to concerns about whether producers would be able to easily provide those data.…”

Antimicrobial resistance in Enterococcus isolated from western Canadian cow-calf herds

“…In Canada, the use of virginiamycin is approved for use in cattle being fed for slaughter to help reduce liver abscesses [ 39 ]. However, virginiamycin use has not been reported in cow-calf herds [ 17 ]. A single sampled herd had an associated feedlot allowing for potential limited exposure [ 17 ]; however, no virginiamycin use was reported in any of the sampled herds in 2020.…”

“…However, virginiamycin use has not been reported in cow-calf herds [ 17 ]. A single sampled herd had an associated feedlot allowing for potential limited exposure [ 17 ]; however, no virginiamycin use was reported in any of the sampled herds in 2020. Resistance to quinupristin/dalfopristin varied between herds with herd of origin having a slight impact on resistance for E. casseliflavus .…”

“…Ciprofloxacin resistance was most common in E. faecium in both the current publication and the American study [ 10 ]. In Canadian herds in 2020, the use of fluoroquinolones at least once was low with only 4.8% ( n = 7) herds reporting the use of fluoroquinolones at least once in the most commonly treated classes of nursing calves and cows [ 17 ]. However, none of the herds in the present study reported use of fluoroquinolones during 2020 [ 17 ].…”

“…isolated from feedlots and sources more likely to be of human origin [ 1 ]. However, this research has not been repeated in cow-calf herds where both antimicrobial use (AMU) and animal management differ greatly from large North American feedlots [ 16 , 17 ]. Certain species of Enterococcus , specifically E. faecalis and E. faecium , are common causes of Enterococcus -related diseases in humans and resistant enterococcal infections have become an increasing threat to human health [ 1 , 13 ].…”