Perceptions of antibiotic use and resistance
Antimicrobial resistance (AMR) limits the ability to prevent and treat infection, making it one of the foremost threats to human and animal health. Animal agriculture's use of antibiotics in food animals is an important factor in AMR. Therefore, policies to reduce antibiotic use and combat AMR in animal agriculture in the United States (US) have been put in place or are being developed. One key to the success of these policies is understanding how veterinarians treating dairy cattle perceive the scale of antibiotic use, the threat of AMR and the utility of antibiotic use policies. The authors of this study by Padda et al (2021) (Preventive Veterinary Medicinehttps://doi.org/10.1016/j.prevetmed.2021.105428) interviewed dairy veterinarians in New York State and conducted an iterative thematic analysis of their responses, through which five themes were identified: 1. veterinarians' views of the frequency and reasons for antibiotic misuse; 2. their ideas on reducing antibiotic use; 3. perceptions of AMR within the dairy industry; 4. view of organic farming and how it relates to animal welfare; and 5. the impact of consumers' beliefs on the dairy industry.
Participants viewed antibiotic overuse as largely a result of farmers' concern for the welfare of their cattle and desire to treat animals quickly. Interviewees believed that it was possible to reduce antibiotic use through regulation, such as the Veterinary Feed Directive and improved herd management activities, such as better colostrum management, culture-based mastitis treatment, and improved housing conditions. They did not view the dairy industry as a significant contributor to AMR, particularly when compared with human medicine. Interviewees also offered their (unsolicited) opinion on organic dairy farming in the US and expressed frustration with the limited treatment options available in organic dairy farming and how this dynamic may potentially compromise animal welfare. Finally, they commented on the impact of consumers' beliefs on the dairy industry, expressing frustration with how misinformation about the dairy industry has led to consumer driven changes. The authors suggest that these findings can help guide future efforts in veterinarian-client communication and the development and implementation of effective policies in New York State. The results also highlighted the need for more quantitative research on antibiotic use in the US dairy industry, as without these data it is difficult to ascertain the true impact of policy interventions. The similarities here between the UK and US situation are interesting to consider.
Probiotics
A systematic review and meta-analysis under-taken by Barreto et al (2021) (Preventive Veterinary Medicinehttps://doi.org/10.1016/j.prevetmed.2021.105433) aimed to appraise the available evidence on the effectiveness of probiotic treatment on mature cattle immunity, inflammation, and disease prevention. An analysis was conducted to answer the following research question: ‘in cattle of at least 6-months of age, is the use of probiotics associated with immunomodulatory and inflammatory responses, and clinical disease outcomes?’ A literature search yielded 25 studies that fitted the inclusion criteria, however only 19 were suitable for inclusion in the meta-analysis. Included studies were assessed for bias using a risk assessment tool adapted from the Cochrane Collaboration's tool for assessing risk of bias in randomised trials. GRADE guidelines were used to assess the quality of the body of evidence at the outcome level. The meta-analysis was performed using Review Manager and R. The overall quality of evidence at the outcome level was assessed as being very low. On average, the treatment effect on immunoglobulin G, serum amyloid A, haptoglobin and β-hydroxybutyrate for cows receiving probiotics did not differ from control cows. Additionally, exposure to probiotics was not associated with reduced risk of reproductive disorders. The authors conclude that there is insufficient evidence to support any significant positive effects of probiotics on cattle immunity and disease prevention, but suggest this lack of consistent evidence could be a result of dissimilarities in the design of studies such as differences in dosage, dose schedule, diet composition and/or physiological state of the host at the time of treatment.
Antibiotic use in diarrhoeic calves
A Canadian study by Gomez et al (2021) (The Veterinary Journalhttps://doi.org/10.1016/j.tvjl.2021.105713) evaluated the impact of a multi-disciplinary intervention to reduce and refine antimicrobial use for treatment of diarrhoea in dairy calves. The intervention consisted of modification of management practices for disease prevention, health evaluation training of farm staff, implementation of an algorithm directed at anti-microbial therapy for diarrhoeic calves, and monthly farm visits. A combination of retrospective (before intervention period [BP], 1 year) and prospective (immediately after intervention period [AP], 1 year) cohorts were used. Health outcomes measured included incidence of diarrhoea and overall mortality. Antimicrobial treatment rates for diarrhoea and total mass of antimicrobial drugs used at the calf and farm level were also evaluated. Records of 2049 and 2251 calves from 10 farms were available in the BP and AP, respectively. Reduced antimicrobial treatment rates occurred on seven farms, but not on three farms in the AP. A total of 85% (1303/1573) and 18% (310/1698) of diarrhoeic calves were treated with antimicrobial drugs in the BP and AP, respectively. Perhaps unsurprisingly given what we have known about the causes of calf diarrhoea for many years now, there were no differences in the incidence of diarrhoea or mortality between periods. In summary a multidisciplinary approach was effective in reducing antimicrobial use for calf diarrhoea on dairy farms without negative impacts on calf health.