Few finisher problems have been more frustrating than those sporadic, unexpected and unexplained deaths of nearly market-ready hogs. These losses are dramatic and costly.
There seems to be a seasonality to the prevalence of hemorrhagic bowel syndrome (HBS). In some finishing groups, often in summer, HBS can account for 75% of all mortalities.
The syndrome usually occurs in fast-growing pigs at 4-6 months of age. Rarely are the problem pigs identified prior to finding them dead in their pens. The carcasses are markedly pale in color with an extended abdomen. Whenever I autopsy these pigs, the producers always tend to step back a few feet.
The root cause of HBS is the subject of debate among veterinarians, researchers and producers. The debate is whether HBS is an infectious disease syndrome or is merely the result of a 180-degree twist or rotation of the entire intestinal stalk.
Those in the “infectious cause” camp strongly believe that these deaths are due to a release of bacterial toxins. Veterinarians who believe this theory think bacteria such as clostridium or E. coli begins growing in the gut; then, due to some event or change, the gut chemistry or flora changes, which allows an overgrowth and release of these toxins. Some farms have seen reductions in HBS cases with strategically placed doses of antibiotics in late finisher feed, giving credence to this theory. Of course, the problem is in the timing of any such protocol.
Veterinarians in the “twisted intestine” camp believe the entire intestinal stalk turns on its axis inside the abdomen creating a situation where blood rushes into the guts via the higher-pressured arteries, but cannot escape due to collapse of the lower-pressured veins. Giving some credence to this theory is the fact that “feed interruption events” can sometimes correlate to increased incidences of HBS.
Also, postmortem tests reveal many victims of HBS have a full stomach and displaced intestines. On occasion, you can actually feel and see the twist of the intestinal stalk. This theory is also given some credence because of spikes in HBS in hot weather.
It is also agreed that larger, older pigs eat far fewer meals while consuming larger quantities at each meal.
The list of “cures” for HBS is long and getting longer. I have informally surveyed veterinarians and producers from around the world and many think they have the answer until the “next turn through the barn.”
This list of cures includes feed and water additives, genetics changes, feeding methods and in some cases, “foo-foo” dust.
Any syndrome such as HBS that is sporadic in nature and of low incidence is very difficult to study in a way to control all of the variables. Researchers have been unable to create field conditions that trigger HBS, again making it a difficult syndrome to study.
This same difficulty in the science leads many to believe that a change they made in the diet or an additive they put in the feed or water worked, when in reality, the problem most likely went away by chance.
A few large studies that have been conducted in field conditions show only a slight reduction in the number of HBS cases when the pigs were fed certain feedgrade antibiotics. But here again, the science is very “thin.”
Last summer, a manager from a large finishing site in the western Corn Belt called to report that while the overall health of his pigs was excellent, 75% of his mortalities were due to HBS.
I had recently heard that distillers dried grains with solubles (DDGS), a by-product of ethanol production, had been helpful in reducing (and sometimes eliminating) cases of HBS.
This finishing site was large and had been filled over a fairly short period of time with pigs of similar health status and the same genetics.
We decided to run a “trial” by adding 200 lb. of DDGS/ton of finishing ration in every other 1,000-head barn, and attempting to hold all other variables constant.
After one month there were no noticeable changes in mortality rates in the DDGS or control barns, and in fact, there were slightly more deaths from HBS in the DDGS-fed barns.
For now we will continue to be frustrated by HBS. The good thing about a frustrating problem such as HBS is there seems to be no shortage of potential “cures” and suggested solutions. We will continue to run field trials in search of the elusive solution to HBS.