Two feed-related issues are addressed in the following case studies: the challenge of diagnosing and treating mycotoxins, and dealing with vitamin E/selenium deficiency causing sudden death in nursery pigs.
Mycotoxins are released from molds in grains when appropriate conditions (moisture, temperature and oxygen) are present. Conditions that allow mycotoxin formation are unique to the specific fungi. Some mycotoxins are formed in the field and some are storage related. Geography plays a role for development of mycotoxins.
Growing conditions such as early frost, drought and/or insect damage can significantly influence the formation of toxins.
Common mycotoxins that affect swine include aflatoxin, ochratoxin, T-2 toxin, vomitoxin (DON), zearalenone (F-2), ergot and the fumonisins.
Case Study No. 1
Over several years, a farrow-to-finish producer expressed concern about the quality of his farm-raised corn relative to mycotoxins. He asked if it was necessary to add products to counteract molds and mycotoxins. He was told mycotoxin screening of feed samples was available from the Animal Disease Diagnostic Laboratory (ADDL), Purdue University.
During routine herd visits, a sample of corn or feed was routinely collected and assayed for aflatoxin, ochratoxin, vomitoxin, zearalenone and occasionally, fumonisins. In 11 years, 34 samples were screened. The only mycotoxin identified was vomitoxin at 2 parts per million (ppm) and 0.5 ppm. Since most of these were corn samples, the level of vomitoxin in the finished feed would have been 20-25% below these levels.
During the collection period, samples were pulled every month except December. Bins were at various fill levels when sampled. Clinical problems could not be attributed to vomitoxin during this period.
When levels reached 2 ppm, binding agents/absorbants were often added until samples turned negative.
This case report depicts a systematic plan of managing mycotoxins. The total cost of the diagnostics was $1,400. If products had been routinely added to feed to treat mycotoxins ($2/ton), the producer would have spent over $20,000 during this period!
Consider devising your plan to monitor feed and/or ingredients and address positive results.
The ADDL at Purdue University tested 108 samples for mycotoxins in the last 12 months. There were 28 positive results for mycotoxins, with 16 due to vomitoxin. Levels ranged from 0.5 ppm to 4 ppm.
It is important to note that toxigenic strains of molds can occur without the production of mycotoxins, and there is little correlation between spore counts and presence of mycotoxins.
In addition, the absence of mold does not guarantee freedom from toxins. Studies reported at the International Pig Veterinary Society meetings in 2000 (Melbourne, Australia) and in 2004 (Hamburg, Germany) showed some promise for control of mycotoxins using a rumen bacterium BBSH 797, a yeast culture Trichosporon mycotoxinivorans or organoaluminosilicates.
Case Study No. 2
Sudden death of good pigs was occurring in a nursery site 7-14 days postweaning. Pigs are purchased out of state and transported weekly to the contract nursery. Acute death of 0.5% of a group occurred over a two-day period. Postmortem of pigs showed significant hemorrhage in the heart muscle (mulberry heart), fluid accumulation in the heart sac and excess fluid in the chest cavity.
Gross diagnosis was vitamin E/selenium deficiency. No bacterial growth occurred on cultures, and microscopic lesions were consistent with vitamin E/selenium deficiency.
Rations were supplemented with maximum allowable levels of selenium and vitamin E.
The producer farrowing the pigs agreed to add an injectable selenium/ vitamin E product to the iron when pigs were processed. The sudden death of good pigs subsided once the treated pigs came through the nursery.
Recently, another episode of sudden death occurred in the same nursery. Five pigs out of two different rooms (1,000 pigs total) died over a two-day period. All five pigs were posted and all showed classic mulberry heart lesions; the microscopic changes were again consistent with vitamin E/selenium deficiency.
Staff at the nursery site had observed a relatively high number of pale pigs on arrival at the nursery, prior to the most recent episode of acute death loss. It was speculated that the pigs had missed iron injections.
Since the level of selenium can't exceed 0.3 ppm, vitamin E levels can be reviewed, water-soluble products added or injectable products strategically used to address this issue.