Targeting therapy to minimize antimicrobial use in preweaned calves: Effects on health, growth, and treatment costs

Abstract

Prophylactic and therapeutic antimicrobial use in food animals is questioned because of the potential for development of resistant bacteria and future inability to use some antimicrobials for human or animal disease. The objectives of this study were to determine the effect of raising preweaned dairy calves without antimicrobials in the milk and minimizing therapeutic antimicrobial treatment on morbidity, mortality, weight gain, and treatment costs. Newborn calves (n = 358) were allocated to 1 of 4 groups, housed outdoors in individual hutches, and monitored for 28 d. Calves in the conventional therapy (CT) group were treated as per dairy protocol with sulfamethoxazole/trimethoprim, spectinomycin, penicillin, and bismuth-pectin for diarrhea. The targeted therapy (TT) group included bismuth-pectin for diarrhea and antimicrobial treatment only in cases of fever or depressed attitude. Within CT and TT groups, calves were equally assigned to receive neomycin and tetracycline in their milk for the first 2 wk of life (AB-milk) or no antimicrobials (NoAB-milk). Daily health evaluations included fecal consistency, respiratory disease, attitude, and hydration status as well as milk and grain consumption. A negative binomial model evaluated the total number of days with diarrhea days in each group. General linear models were used to assess average daily weight gain and grain consumption. Conventionally treated calves had 70% more days with diarrhea than TT calves, and AB-milk calves had 31% more days with diarrhea compared with NoAB-milk calves. The TT calves tended to have a higher average daily gain by 28 d and consumed more grain compared with CT calves. If antimicrobials were used only for diarrhea cases with fever, inappetence, or depression and no in-milk antimicrobials were used, a $10 per calf savings could be realized. Targeting antimicrobial therapy of calf diarrhea cases is prudent not only to save the drugs for future use but also to prevent the potential for antibiotic-associated diarrhea and reduce calf-rearing costs.

Food Animals and Antimicrobials: Impacts on Human Health

“…In contrast, Dumonceaux et al reported a significantly increased body weight (10%) and a 7% increase in feed efficiency with the AGP virginiamycin, but only for the first 15 days (55a). In short, improved farming practices and breeding programs, which may include reduced animal density, better hygiene, targeted therapy, and the use of enzymes, prebiotics, probiotics, and vaccines, appear to have at least partially replaced the beneficial aspects of antibiotic growth promoters (27,158,160).…”

The livestock reservoir for antimicrobial resistance: a personal view on changing patterns of risks, effects of interventions and the way forward

“…There is, however, very little hard evidence documenting the negative or positive effects of reducing the usage, especially under real life conditions. Berge et al [79] performed an intervention study on a single dairy cattle farm where all pre-weaned calves routinely received prophylactic antimicrobial treatment for diarrhoea. They compared this normal routine with a changed strategy where only calves showing clinical symptoms were treated.…”

Evidence-Based Use of Antibiotics in Veal Calves with Diarrhea

“…Calves treated prophylactically for calf diarrhea during the first two weeks of life with neomycin or tetracycline in the milk had lower weight gain, lower feed intake, and more days with diarrhea than calves not receiving antibiotics in the milk. However, the use of antimicrobials other than in-milk antimicrobials used in calves with diarrhea, fever, anorexia and depression was beneficial [27]. The use of antibiotics is recommended in diarrheic calves with systemic signs of disease including anorexia, dehydration, lethargy, fever, or when the diarrheic stool contains blood or sloughed mucous membranes.…”