Farming Magazine - April, 2014

COLUMNS

Beef: Scours in Beef Calves

By Dr. Michael J. Baker

According to the 2011 USDA National Animal Health Monitoring System report "Cattle and Calves Nonpredator Death Loss in the United States," 2010 nonpredator calf losses on beef farms due to scours and related intestinal diseases accounted for 10.4 percent of total losses. This is down from 19.2 percent in 1991. In 2010, herds with fewer than 50 cows had a lower rate (8.3 percent) compared to larger herds, indicating that better prevention and care is being provided.

Regionally, the Northeast is about in the middle of the pack, losing 13.3 percent to scours and intestinal disorders compared to the Northwest, North Central and Southwest regions (14.5 to 15.1 percent) and the South Central and Southeast regions (5.4 to 7.5 percent). The good news is that death loss due to scours has been on the decline, but it still accounts for significant loss. In fact, reducing death loss due to scours by 5 percent is equal to a 5 percent increase in weaning weight. Reducing scours is something you can do now; improving weaning weight by genetics will take 16 to 18 months. Imagine the financial return when reducing scours and increasing weaning weight. Even if the scouring calf doesn't die, research has shown weaning weight and carcass quality are negatively affected. In addition, there are the financial and labor costs of treatment.

Cause

Calves become infected when exposed to infective agents in the environment. Dirty bedding, udders and mud are easy routes of infection for the young calf. Potentially dangerous organisms also occur naturally in the gut. A calf becomes infected when its resistance is lowered by stress, enabling the infective agent to multiply. Every calf is repeatedly and often unavoidably subjected to stress: fatigue of birth, chilling from wind and/or wetness, severe temperature extremes, underfeeding and overfeeding.

The most common infective agents are bacteria, including E. coli, salmonella and Clostridium perfringens; viruses such as rotavirus and coronavirus; and protozoa such as cryptosporidium and coccidia.

Bacteria typically attack the intestines by pumping excess water into the intestines or producing toxins, while viruses kill intestinal cells, thereby reducing absorption. Either way, the result is runny, watery manure known as scours. Note: When handling scouring calves, it is important to understand that E. coli, salmonella and cryptosporidium can cause serious disease in humans; treat all scouring calves with caution to prevent infecting yourself.

  • Prevention - Developing a prevention strategy requires an understanding of the mode of infection over time. Adequate intake of colostrum within the first hours after birth provides passive immunity to infection. This immunity declines over time. Active or acquired immunity begins at birth and eventually replaces passive immunity from colostrum. In Figure 1, you can see that these lines cross at about 10 days from birth. As such, most of the scours and the greatest risk of infection will be when immunity is lowest, which is when the calf is 1 to 2 weeks of age.




  • Figure 1
    Courtesy of Dr. David Smith, University of Nebraska-Lincoln.
    If the newborn calf is too weak to nurse or the cow does not have good colostrum, maternal colostrum or a colostrum replacer should be administered with an esophageal feeder. In some herds, selenium or vitamin E supplementation for the newborn calf may be needed to strengthen the immune system. Consult your veterinarian.
  • Nutrition - Your goal as a manager is to increase both colostral and active immunity. As in most cases, the first line of defense is nutrition. Calves born to mature cows with a body condition (BCS) score of 5 to 6 and first-calf heifers with a BCS of 6 to 7 will have higher levels of immunoglobulins in their bloodstream than those born to dams with a lower BCS. Body condition is mostly a function of energy intake, but the cows also need to be provided adequate crude protein (8 to 10 percent CP) and a complete mineral.
  • Selection - Second is mothering ability and udder/teat structure. A cow that doesn't encourage the calf to nurse will reduce the colostrum intake. A cow without a tight udder conformation or with teats that are too big reduces the likelihood that the calf can physically nurse. This type of mammary structure is also prone to be mud and manure-covered, increasing the risk of ingesting disease-causing agents. These cows should be marked at calving for culling. Assuming that she weans a calf, you're likely to have forgotten the problems you had six months earlier.
  • Vaccination - Finally, if you've been having problems, consider a vaccination program for the cow. There are several good vaccines available. Consult your veterinarian for recommendations. These vaccines are killed, which means that booster doses must be administered. They also have to be given six to 16 weeks prior to calving, so timing is critical. Oral antibody products are also available to give to the newborn calf if E. coli is a problem on the farm, and an oral vaccine can be given to protect against the viral diseases if they have been diagnosed.
  • Environment - If the calf is born in unsanitary conditions, no level of nutrition, animal selection or vaccination will overcome the disease challenge. A calf's first meal must be from a clean cow; if it has to suck on mud balls before finding the teat, much of your previous effort will be wasted. In part, this is why many farmers calve in January/February or May and later. Mud season in the Northeast is March and April, and the conditions are prime for transmitting scours.

There's one other factor related to environment and time. The environment becomes increasingly contaminated as the calving season progresses. This is the concept behind the Sandhills Calving System. Basically, after a group of calves is 1 week old, the cows that have not calved are moved to a clean pasture or paddock. This reduces the risk of exposing 1 to 2-week-old calves, which are most susceptible to scours, to infective organisms being shed by older calves. For small herds this may not be practical, but if scours is a problem, the results of implementing this system have been significant. For more details, visit http://bit.ly/NvSw5W.

Detection

Despite your best efforts, scours will sometimes occur. Calves that are bouncing around the pasture are probably OK, even if they're excreting runny yellow or white manure. Obvious signs are lethargy, droopy ears, slowness in getting up, and a manure-covered tail. Calves that are scouring are dehydrated. If you pinch the skin and it does not go back to normal quickly, this is an early sign. In severe cases, the eyes will be sunken. The nose and eyes might be dry. The temperature of sick calves will often be less than 100 degrees Fahrenheit. Also watch for cows with distended udders, which indicate that they have not been nursed. Keep a close eye on first-calf heifers, as the quality of their colostrum is lower than that of colostrum from mature cows, and their mothering instincts are not as strong.

Treatment

Scouring calves will go down quickly, and if not treated they will die. First, use a rectal thermometer to determine body temperature. If it's below 100 degrees Fahrenheit, the calf must be warmed up before starting therapy. Then, replacing lost fluids is the first line of attack. Most likely the calf will not nurse, so administering fluids via esophageal feeder or stomach tube will be necessary. Warm, balanced electrolytes given at a rate of 1 to 2 quarts three times in 24 hours and up to 4 quarts of warm milk (preferably from the dam, but milk replacer can be used) in 24 hours are recommended. Treatment may take several days.

In severe cases, a saline solution with bicarbonate and dextrose will be given intravenously. Unless you're experienced in this procedure, veterinary assistance will be necessary. Some recommend the use of antibiotics to prevent secondary infection; this should only be done in consultation with your herd veterinarian. A calf coat may protect the weakened calf from further chilling.

Summary

  • Prevention is the best strategy. The environment, along with cows' udders and teats, should be clean and dry.
  • Maintain a BCS of 5 to 6 in cows and 6 to 7 in heifers.
  • Ensure that calves nurse within one to two hours of birth.
  • Cull females with poor mothering ability and low-slung udders and big teats.
  • Consider vaccination of dams.
  • Reduce contamination by limiting stocking density and moving cows not yet calved to clean pasture/paddock.
  • Early detection is a must - especially observe first-calf heifers.
  • Administer fluid therapy early and often.
  • Develop a written protocol for prevention, detection and treatment of scours.

Michael J. Baker, PAS, Ph.D., is a beef cattle extension specialist with Cornell University and a new columnist for Farming magazine.