Improving animal health offers a rewarding way to reduce antibiotic use.

The development of antibiotic resistant bacteria is a continuing concern in both human and animal health. In response, human medicine has implemented widespread antibiotic stewardship policies, which aim to optimize antibiotic use to preserve the effectiveness of these invaluable medications. As these policies have changed the face of human medicine, concern has developed among consumers, regulatory agencies, and within the livestock industry itself about antibiotic use in animal agriculture.

 

On dairy operations, the greatest use of antibiotics is in the treatment of mastitis; however, a large population of antibiotic resistant bacteria that could impact human health are found in pre-weaning calves. Several studies have demonstrated a greater prevalence of resistant Salmonellaand E. coli in pre-weaning calves, as compared to older animals (Ray et al., 2007; Edrington et al., 2008; Awosile et al., 2018). While the reasons behind the increased risk of antibiotic resistant bacteria in young calves are not well understood, antibiotic stewardship programs focused on the dairy calf could help to reduce this source of resistant bacteria on dairies. Stewardship programs revolve around the concept of judicious use of antibiotics, which encompasses properly utilizing antibiotics, along with reducing the use of antibiotics. Often, dairy producers become concerned by the notion of reducing antibiotic use through the implementation of regulations or restrictions (Habing et al., 2016). But, a workable and rewarding way to reduce antibiotic use is to reduce the need for antibiotics through improved animal health.

 

Poor colostrum quality and/or inadequate intake results in failure of passive transfer (FPT), leaving calves with low immunoglobulin levels in the serum and little protection from disease. A recent French meta-analysis estimated the overall cost of a case of FPT to be $69.11 (based on € conversion; Raboisson et al., 2016). The financial losses of FPT in this study were due to calf mortality ($10.86), bovine respiratory disease ($10.86), calf diarrhea ($9.95), and decreased daily weight gain ($37.44; Raboisson et al., 2016). Although these numbers were calculated using French market data and may not accurately estimate the costs in the US market, they do clearly demonstrate that FPT is expensive.

It is estimated that over 19% of heifer calves on US dairies experience FPT (Beam et al., 2009). Failure of passive transfer on a 500-cow dairy could cost over $3,200 per year. Prevention of FPT requires assurance that calves receive a sufficient quantity of good quality colostrum delivered quickly after birth. More information on colostrum management and prevention of FPT can be found in Feeding the Newborn Dairy Calf . Development of a strong colostrum management protocol contributes to antibiotic stewardship through reductions in the need for antibiotics, all while bringing a financial benefit to the operation.

Although colostrum management changes may be undertaken with or without the involvement of a veterinarian, the farm veterinarian will always play a vital role in antimicrobial stewardship by guiding antibiotic use through veterinary feed directives and written treatment protocols based on their knowledge of the farm assured through a strong veterinary, client, patient relationship. The treatment of calf diarrhea provides an excellent example of how veterinarian-developed treatment protocols can be beneficial to the farm. Calf diarrhea can be caused by bacteria, viruses, or even nutritional changes; so, the use of antibiotics is not always necessary. Generally, veterinarians agree that maintaining hydration is essential to managing calf diarrhea, but the need for antibiotics may vary from case to case. Despite this, 13% of conventional producers utilize antibiotics to treat even the mildest forms of diarrhea, with this increasing to over 50% in some moderate cases (Habing et al., 2016).

The value of veterinarian-developed protocols was demonstrated in a study (Berge et al., 2009) comparing a dairy operation’s conventional calf diarrhea treatment method to a more targeted approach. The two protocols were similar in providing supportive care to the calf, but differed in antibiotic choices (multiple over-the-counter and/or prescription vs. prescription only), and, in the more targeted approach, antibiotic use was restricted to only calves with a fever. These protocol changes resulted in a reduction in days with scours and many fewer antibiotic doses, resulting in reduced treatment costs (including labor and medication) of $9.60 per calf, despite the targeted protocol using an antibiotic that costs more per dose. One other factor in this study was that the conventional treatment protocol was administered by the farm’s employees, while the targeted protocol was administered by trained study personnel. Differences in the ability to recognize scours and classify its severity may also have contributed to the economic benefits observed in this protocol change. Although this makes it more difficult to directly compare these protocols, it does demonstrate that a program incorporating both treatment protocols and personnel training can be effective. Likewise, in another study, implementing a similar change on two different dairies, a calf was 80% less likely to be treated with an antibiotic, yet there were no differences in animal health when comparing calves raised before the protocol change to those raised after (Gomez et al., 2017). Investing in the development of veterinarian-directed treatment protocols and the farm personnel training needed to properly implement them may seem time consuming and expensive; nonetheless, this approach can significantly reduce antibiotic use while improving animal health, which benefits both antibiotic stewardship and farm profitability.

Antibiotic resistant bacteria will continue to be a challenge in managing the health of all species. Although the implementation of the Veterinary Feed Directive, aimed at improving antibiotic stewardship through veterinary involvement in antibiotic use decisions, brought along a few headaches, it is important to maintain a positive attitude towards antibiotic stewardship. There are many ways that antibiotic stewardship can be implemented on dairies that will reduce antibiotic use, all while benefitting animal health, productivity, and the farm’s bottom line.

References:

Awosile, B., J. McClure, J. Sanchez, J. C. Rodriguez-Lecompte, G. Keefe, and L. C. Heider. 2018. Salmonella enterica and extended-spectrum cephalosporin-resistant Escherichia coli recovered from Holstein dairy calves from 8 farms in New Brunswick, Canada. J. Dairy Sci. 101:3271-3284.

Beam, A. L., J. E. Lombard, C. A. Kopral, L. P. Garber, A. L. Winter, J. A. Hicks, and J. L. Schlater. 2009. Prevalence of failure of passive transfer of immunity in newborn heifer calves and associated management practices on US dairy operations. J. Dairy Sci. 92:3973-3980.

Edrington, T. S., T. R. Callaway, R. C. Anderson, and D. J. Nisbet. 2008. Prevalence of multidrug-resistant Salmonella on commercial dairies utilizing a single heifer raising facility. J. Food Protect. 71:27-34.

Gomez, D. E., L. G. Arroyo, Z. Poljak, L. Viel, and J. S. Weese. 2017. Implementation of an algorithm for selection of antimicrobial therapy for diarrhoeic calves: Impact on antimicrobial treatment rates, health and faecal microbiota. Vet. J. 226:15-25.

Habing, G., C. Djordjevic, G. M. Schuenemann, and J. Lakritz. 2016. Understanding antimicrobial stewardship: Disease severity treatment thresholds and antimicrobial alternatives among organic and conventional calf producers. Prev. Vet. Med. 130:77-85.

Raboisson, D., P. Trillat, and C. Cahuzac. 2016. Failure of passive immune transfer in calves: A meta-analysis on the consequences and assessment of the economic impact. PLoS One. 11:e0150452.

Ray, K. A., L. D. Warnick, R. M. Mitchell, J. B. Kaneene, P. L. Ruegg, S. J. Wells, C. P. Fossler, L. W. Halbert, and K. May. 2007. Prevalence of antimicrobial resistance among Salmonella on midwest and northeast USA dairy farms. Prev. Vet. Med. 79:204-223.