Mycotoxins are fungi capable of producing mold on virtually all small grains, including corn.
The term mycotoxin means “poison from a fungi.” Only about 60 of the 200,000 known species of molds have been shown to harm humans or livestock. These fungi grow on virtually all of the small grains, including wheat, oats, barley and, of course, corn, the main source of pig feed.
These molds can proliferate in the ear of corn prior to harvest when there is drought or during prolonged periods of cool, wet weather. After harvest, corn that is improperly stored or dried can also produce molds. These “hot spots” in storage facilities may contain high concentrations of mycotoxins, which contaminate grain destined for feed production.
Symptoms of mycotoxicosis are extremely variable, and can range from reproductive failure in the sow to poor performance in the finisher. The typical mycotoxins include aflatoxin, vomitoxin, zearalenone and ochratoxin.
Case Study No. 1
A 1,200-sow, farrow-to-finish operation produced its own gilts on a separate site. Mature gilts were transported to the sow farm for breeding. Even though the gilts were old enough and big enough, breeding success was extremely poor. Nearly one-third of the gilts failed to breed or conceive.
Infection was suspected. Records were closely examined to verify age. Breeding procedures were reviewed to verify appropriate boar exposure and heat detection techniques. Artificial insemination protocol was checked. Blood tests were done on several females that hadn't cycled.
Sampling suggested no evidence of disease infection. A walk-through of the gilt developer farm revealed three rooms of healthy, active gilts.
However, the caretaker mentioned that gilts in the two older rooms had experienced a number of rectal prolapses. Closer inspection revealed a number that appeared to be in estrus and also had some pronounced mammary development. These signs pointed to exposure to estrogenic compounds produced by molds.
The bulk bins were examined and the two supplying feed for the older two rooms had large, moldy chunks attached to the sides. Rivets had rusted through and rainwater was allowing feed to get wet and mold to grow. High levels of zearalenone were detected.
The producer emptied the bins, repaired them and added mold inhibitor to feed delivered. Within three months, gilts going to the sow farm were achieving over 90% fertility success.
Case Study No. 2
A 600-sow, farrow-to-feeder pig farm experienced poor performance. The herd was positive for PRRS (porcine reproductive and respiratory syndrome). Sow reproductive performance was fair, but feed intake in farrowing was below expectations, and smaller weaned pig performance was subpar in the nursery.
The farm had changed feed suppliers during the past 12 months. Extensive diagnostics of blood from sows and tissues from suckling pigs and poor nursery pigs failed to reveal an infectious agent. Because of poor feed intake in farrowing, samples were collected from the bulk bins delivering feed. Several samples contained over 200 ppb aflatoxin. The feed supplier was notified about the findings.
It was determined that incoming corn wasn't properly tested, nor were the fines being screened out. The main corn bin leading to the milling equipment hadn't been totally emptied or cleaned in several years. The bin was emptied and a large amount of fines was discovered in the bottom of the bin. That material tested over 1,000 ppb of aflatoxin.
The mill agreed to improve the protocol for receiving grain and screening it for aflatoxin. Feed was delivered to the farm after all the bins were cleaned. All phases of production showed improvement within a month of getting “clean” feed.
Steps to Reduce Mycotoxins
While bacteria and viruses can cause clinical disease in pigs, feed-related issues can mimic or exacerbate many conditions. These steps should reduce the effects or risks of mycotoxins from feed:
Review grain receiving/handling process for feed suppliers.
Keep samples of each delivery.
Check all bins and delivery tubes for contaminated feed.
Report clinical signs to your health advisor, including chronic loss of appetite, newborn gilt pigs with swollen vulvas or poor reproductive performance.
Test feed/grain for mycotoxins when conditions warrant.
Add mold inhibitors to diets of sows and nursery pigs. Aluminosilicate and bentonite products are helpful in binding aflatoxins to prevent absorption.
Use your veterinary advisor to assist in evaluation of your herds' health and production parameters. Now that feed is much more costly, make sure it is good.