March 1, 2019

Today’s modern chicken and turkey is best classified as an intestinal athlete. When things are in a steady state and the food being ingested is being properly digested and turned into poop, the best analogy I can think of is a well-rehearsed symphony orchestra playing Tchaikovsky’s 1812 Overture. When things are upset and the steady state is disrupted the analogy would change to the worst middle school band recital that you have ever had to endure.

Most of the time when chicken people are talking to me about enteritis, they are referring to necrotic enteritis (NE). Unfortunately, NE is the end stage in a complex series of events occurring in the intestinal tract. Our goal, as producers, should be to try to control the early disruptions to the steady state of the intestinal tract before the problem progresses to frank mortality.

The early stages of enteritis are known by various names including dysbacteriosis, flushing, and feed passage. Clinical signs can be subtle and include mucoid to watery intestinal contents, thinning of the intestinal wall, and unthrifty appearing animals. Skinner, et. al. in a study published in BVS Midwest Poultry Show Edition March 2019 Avian Diseases reported that subclinical enteritis can reduce growth rate, increase feed conversion and cost producers more than $1000 per flock.

Diet obviously has a major influence on preserving the steady state condition of the intestinal tract. Unfortunately, in the field we don’t usually have control over the ingredients that are being used in the diet for our animals. It is our obligation, however, to report any unexpected changes in color, consistency, or smell of the feed in the pans. All ingredients are not the same and the quality of ingredients can certainly be variable. We rely on the feed mill to use only the best quality ingredients, but sometimes things happen and the personnel at the feed mill don’t even realize it unless we in the field report what we are seeing and what is happening.

With respect to diet, the biggest factor which we absolutely have control over is the availability and presentation of feed. Today’s modern chicken or turkey without feed consistently running through its intestinal tract is like a Tour de France cyclist without anabolic steroids running through his system. Birds, especially turkeys, are very much creatures of habit and they like to eat feed in the same form meal after meal. If they don’t see that they start searching for what is the familiar form of feed and rake feed out of the pan rather than eating it. In broilers, the problem is simpler – they are bred to be eating machines and if there is not feed in the pans they are going to eat whatever is close, usually litter. We can and should control these disruptors of the steady state in the field. Never let the animals run out of feed and if the crumble quality is not what it should be put paper on the floor and spread some feed on the paper. It may be the same feed, but remember the animal is used to seeing it in a pan not on paper so it is a novel presentation and their natural curiosity will prevail.

Next in line of disruptors of the steady state are disease challenges. These challenges range from bacterial challenges (Salmonella) to viral challenges (Reo, HEV). The most consistent challenge facing birds in the field, however, is the challenge from coccidia. In the field, it is unusual for us to have any input into what the actual control program is going to be, but we do have control over the program’s success. The oocysts that are shed by a bird are not infective until they go through a maturation called sporulation. Sporulation generally can occur within 24 hours under optimal conditions of temperature and humidity. Keeping the proper moisture level in litter is of critical importance. Too dry and sporulation does not occur, too wet and massive sporulation and challenge occurs. In addition, enteric pathogens such a Salmonella are enhanced by wet warm conditions so not only are the unsuspecting birds being challenged with a high load of sporulated oocysts but they are also salad dressing in the form of intestinal pathogens.

Supportive therapy is also useful in helping to stabilize the steady state of the intestine in a disease challenge situation. Unquestionably, the most effective supportive therapy is penicillin added to the drinking water. As this is no longer an acceptable treatment option in many programs, many practitioners have resorted to the off-label use of many “alternative” products. The term off-label is used because most of these products are labeled as nutritional supplements or odor control products and can make no claims about disease control. One cautionary note – many of these products have gained the reputation of helping to control enteritis via control of coccidia. Three years of research at the BVS Center for Science and Technology has failed to demonstrate any consistent and reliable reduction in oocyst counts for a variety of Yucca products, Essential oil products, Algae based products, and Oregano. As work on this project continues, we hope to be able to demonstrate efficacy against a reduced cocci challenge but using our traditional heavy challenge we have been unable to reliably and reproducibly reduce the oocyst counts in treated groups versus controls. This does not mean that these products do not play a role is stabilizing the steady state – they do. It just means that the mechanism by which they are helping is not by interfering with cycling of the organism.

Another form of supportive therapy being used in the field is treatment with copper in various forms. While the antibacterial characteristics of copper have been well established, it certainly is not as effective of its notorious cousin penicillin. Copper is also very irritating to the mucosa of the upper gastrointestinal tract consistently causing ulcers. Some of these can be very large. In addition, copper is non-selective in its antibacterial actions and can cause significant alterations in the microflora of the intestinal tract. For these reasons, if using copper, the recommendation is to limit use of the compound to as short a duration as possible and upon cessation of treatment, treat the flock with a water-soluble probiotic containing both Bacillus spp. and Lactobacillus spp. to try and restore the steady state as soon as possible.

In the field our goal is to try to establish and maintain the steady state of the intestinal tract. While we do not have control over a lot of things, there are things which we can control. Controlling those things can be the difference between success and failure of a flock. As our knowledge and tools continue to improve, it is reasonable to expect that achieving that hallowed steady state is both achievable and sustainable. The winner will be the conductor (grower) who can organize the orchestra to play the 1812 Overture.

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Robert L. Owen, V.M.D., Ph.D., ACPV

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