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The common sense part of calf scour prevention

Biosecurity isn’t about beating bugs — that’s impossible. Biosecurity is about controlling the line of scrimmage between disease, host and environment. Nowhere is that more important than during calving season when the highly vulnerable newborn is dropped into an inhospitable world.

Biosecurity is about managing risk. It’s a thinking game. On-ranch biosecurity is about sticking to principles that minimize the introduction and transmission of disease. Here are a few:

Animal separation

Calves from heifers face a greater risk of getting sick. Heifers produce smaller amounts of lower quality colostrum. As well, heifers have poorer mothering skills and are more likely to experience calving difficulty. Deal with these problems at the start of the calving season when things are the cleanest and the least harried.

Consider the calving grounds a controlled environment. This is where limiting exposure to disease causing organisms or pathogens is most critical and factors like overcrowding, cold and dampness affect the ability of calves to resist disease. Simple things like keeping the udders of nursing cows clean and the calf’s environment dry and comfortable as possible are important first steps in controlling scours.

The risk of developing disease is a function of challenge (dose of pathogens) and the length of time animals are exposed. Crowded conditions increase the risk of disease on both counts. What are often overlooked is how these factors change over time and how the risk of getting scours changes as calving season progresses.

The most important source of infectious organisms for calves is the adult cow. Most of the important pathogens for calves are normal inhabitants of the adult gut and the number of harmful bacteria, viruses and protozoa shed into the environment by cows increases exponentially during the calving season. Sick calves become additional multipliers to the countless billions of infectious organisms that blanket the calving environment. Calves born later in the calving season are exposed to higher levels of potential pathogens. Unchecked, the numbers of pathogens overwhelm any calf’s ability to resist disease. Calves born later in the calving season are at greater risk for disease or death. In consideration of the growing risk, the Nebraska Sand Hills Calving System offers basic, yet important management options1.

In summary, the Sand Hills system effectively neutralizes extended contact among beef calves by: 1) segregating calves by age to prevent direct and indirect transmission of pathogens from older to younger calves, and 2) scheduled movement of pregnant cows to clean calving areas to minimize environmental contamination and contact time between calves and the larger portion of the cow herd. The objective: to recreate starting conditions of the calving season each week by having new calves dropped in uncontaminated areas, free of older, infective calves.

Start clean, stay clean.

Preventing scours is a matter of controlling pathogen numbers and maintaining resistance at a level higher than the risk of infection. It’s a delicate balance.

Temperature and moisture play a role. Mud and snow favour the buildup of pathogens. Cold can be a stressor that impairs the ability of calves to resist disease. Biosecurity in a sewer isn’t achievable.

Many cow-calf operations have a nurse area for newborn calves, a place to dry them off, administer colostrum and maybe apply tags as needed. These same areas become a source of infection if they double as hospital pens for treating sick calves or cows.

Another cardinal sin during calving season: trips to the local auction market. Auction markets represent a cesspool of disease to the newborn and should be considered off-limits during calving season unless care is taken to clean boots and change clothes at home. Mental lapses that occur under the influence of the auctioneer’s patter and the slap of a gavel are another reason for producers to avoid auction markets while cows are calving at the ranch. Let’s call them the auction mart specials, the orphan calf that sells for next to nothing or the nurse cow that walks into the ring for reasons unknown. Everyone knows better, yet logic is blunted by the aroma of cigar smoke, sale yard coffee and manure.

Follow basic rules of sanitation when treating sick calves. Use disposable gloves. Wash hands frequently. Disinfect boots and change clothes often. Leave treating sick calves until after you have handled healthy ones — never before. Disinfect all balling guns or esophageal feeders after treating sick calves. Have a number of simple hand washing and disinfection stations around the calving area with a few jugs of warm water, disinfectant soap and several cheap coolers to keep things from freezing. A few simple rules and a dash of imagination means those in charge of the calving barn solve problems rather than create them.

Managing colostrum quality and scour vaccines

Ensuring every calf receives three litres of high quality colostrum within several hours of birth is the golden rule of disease prevention in the calving barn. It should be at the top of any biosecurity protocol. The quality of colostrum is affected by nutrition of the dam and vaccines.

There are a number of excellent vaccines for rotavirus, coronavirus, and E. coli K99. Vaccines are administered to pregnant cows and heifers during the last three months of pregnancy to stimulate antibody production in colostrum. In many ways, colostrum kick starts an immune system unprepared for the war it faces when calf meets pathogen the second it’s born and is a critical lifeline.

Colostrum substitutes containing protective antibodies are a good second choice when fresh colostrum is unavailable. Discuss choices, quality and availability with a veterinarian.

Nutrition of the dam Nutrition is normally not considered a part of biosecurity, but should be because disease prevention and control in an undernourished herd is often fruitless. “Ration roulette” presents many risks for the brood cow and calf.

For starters, the immune system of the cow and her colostrum is dependant on dietary protein and a host of essential nutrients. Nutrition of the cow affects the ability of the calf to resist other diseases like white muscle disease caused by vitamin E and selenium deficiency.

Many experts agree that this is a worthwhile practice to supplement cow rations with anticoccidials like Rumensin and Deccox to control the shedding of coccidia, a common parasite in the gut of adult animals. Coccidia on their own and in combination with other pathogens can cause scours.

Feed analysis and ration formulation, including trace mineral supplements, should be a chapter in the biosecurity protocol for ranches.

Control vectors that spread disease.

The farm dog, barn cats, birds and rodents can all be part of biosecurity breaks.

People and staff need to be aware that they, themselves, become vectors of disease if basic rules of hygiene are not followed.

Tools used around the calving shed like calf jacks, syringes and needles, balling guns and esophageal feeders can all transmit disease if not cleaned and disinfected properly. Disposable needles and syringes should be discarded after use.

Know what you are dealing with Fighting a war is impossible without knowing the enemy. Because infectious scours can be a complex, multi-faceted disease (Table 1) the right diagnosis precedes any meaningful control program and plans for the future. Determining what organism(s) is involved is step one. Appropriate tissues, including dead calves need to be submitted to a diagnostic laboratory. Not uncommonly, multiple submissions are necessary.

Conclusion

A biosecurity plan for the calving season starts with understanding the

About the author

Columnist

Dr. Ron Clarke

Dr. Ron Clarke prepares this column on behalf of the Western Canadian Association of Bovine Practitioners. Suggestions for future articles can be sent to Canadian Cattlemen ([email protected]) or WCABP ([email protected]).

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