5. Medicated Milk Replacer
Gretchen asks Dr. Karl, “Besides the additional cost and low dose of antibiotics being used, are there any other disadvantages to using medicated milk replacer instead of non-medicated milk replacer?”
NAHMS Dairy 2002
The 2002 National Animal Health Monitoring System (NAHMS) dairy report1 indicates that scours and respiratory disease were by far the most common reasons for antibiotic use in dairy calves.
Overall, about 56% of dairy farms used medicated milk replacer. A higher proportion of medium-sized operations (64.1%) fed medicated milk replacer to heifers at least occasionally compared with large or small operations (37.7% and 54.4%, respectively). Oxytetracycline with neomycin was the most commonly used medication, and chlortetracycline was also used occasionally.
Dr. Karl replies, “Any use of antibiotics can contribute to the
development and maintenance of antimicrobial resistant bacteria. Such
resistant bacteria may eventually lead to treatment failures on farms
if antibiotics are needed for treating sick animals. Also,
antimicrobial resistance genes may be transferred to human pathogens
and can eventually find their way to people via direct animal contact
or through meat or milk products. Another problem is that the use
of medicated milk replacer can result in residues in meat, such as
neomycin drug residues in veal (7).
Dr. Karl continues, “Antibiotic resistance may develop more quickly when subtherapeutic levels of an antimicrobial are used, such as the low levels used in medicated milk replacer (8). High doses of antibiotics tend to kill the entire target bacterial population and can also kill most of the commensal bacteria. In contrast, low doses of antibiotics are more likely to select for bacterial subpopulations with antibiotic resistance traits, thereby allowing these subpopulations to survive and reproduce (8). These commensal bacteria are ‘innocent bystanders,’ but they can still develop resistance traits that can eventually be shared with their more pathogenic bacterial relatives and neighbors.”
NAHMS Dairy 200714
The most recent NAHMS survey found very similar information to what
as found five years previously on the 2002 survey.
– 57.5% of dairy operations used medicated milk replacers (MMR).
– Use of MMR was less common in larger operations (43.6%)
– The most common medicants for milk replacer were:
–Oxytetracycline with or without neomycin (71.4%)