Management as crucial as the coccidostat you choose
Dairy farmers and calf raisers who use coccidostats are often frustrated that calves still become infected.
But it might not be the cocciostat’s fault. "Treatment failure may be the result of inadequate access to the drug in the feed, delivery of an inappropriate dose of the treatment drug, delayed treatment, inadequate duration of treatment, drug resistance or reinfection," says Sheila McGuirk, a veterinarian with the University of Wisconsin’s vet school.
The first step in diagnosing a Coccidia problem is confirming you have a Coccidia problem. "Not all diarrhea problems in young stock are due to coccidosis," McGuirk says.
To confirm diagnosis, clinical signs—unthrifty calves, slow growth, loose manure—need to be present in more than 20% of the animals. Fecal samples should also show:
- Thirty percent or more of individual samples have 1,000 oocytes per gram (opg) or more.
- Pooled fecal samples of two to five animals have 500 opg or more.
- Composite fecal samples from a scrape alley have 500 opg or more.
"Treat infected animals to minimize oocyst shedding into the environment. Labeled drugs for treatment of coccidiosis are Amprolium, Sulfaquinoxaline and sulfamethazine," McGuirk says.
The best way to rid pens of coccidia is to completely empty the pen, disinfect with a combination of disinfectants and leave the pen empty for several days.
Clean, dry bedding is essential. Add 35 lb. to 50 lb. of bedding per calf each week. Compost packs must be tilled daily (preferably twice each day) to a depth of 10" to 12".
Don’t overcrowd. Provide 34 sq. ft. to 80 sq. ft. of pen space per heifer from eight to 20 weeks of age.
Pens must be adequately ventilated. You might need to add positive pressure ventilation tubes to ensure adequate fresh air exchange.
Provide enough feed and water space. "Bunk space requirements go up with a minimum of 15" per heifer from four months to eight months, up to 24" per heifer up to a month before calving," McGuirk says. Also, provide 12" of linear water space per 10 animals and clean waterers daily.
Feed management is critical. "On a per-head basis, make sure that the milligram per kilogram dose that will be delivered to each calf at the current level of feed intake is adequate for prevention," McGuirk says.
Also, make sure all calves can eat at the same time so that more aggressive calves can’t sort grain and forage. Timid calves then have less opportunity to consume the required amount of coccidiostat to prevent disease.
"A common problem I observe is heifer feed bunks have forage on one side and grain on the other," she says. "This choice puts some heifers at risk for consuming too little of the Coccidia control drug and others at risk of ruminal acidiosis."
Finally, minimize stress to calves as much as possible. Stressful handling, late dehorning, frequent vaccinations, respiratory disease and lameness can all lead to calves eating less—and therefore not getting the correct dosage of the coccidiostat.