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Animal Health

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Livestock Production
Friday, August 19, 2005 5:41:23 PM
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Mycotoxins and their implications in gilts and Gilt Development Units
Fergus J. Neher

Biomin USA



The raising of gilts, later to serve as replacements for integrated sow herds has become a crucial part of pig production and reproduction. In recent years, with the advent of integrated systems, so-called "Gilt Development Units" (GDU) have been created to take in gilts and raise, select and finally provide these gilts to the sow herds. Health, management and timing or scheduling played an important role, as these gilts represented the replacements necessary for one or various sow units.


Difficulties often arose incorporating these gilts at the right time and much effort was put into the correct raising and scheduling of the groups or individuals. The final objective was to get the gilts farrowing at the right time, and to fill the farrowing schedule determined by the cull sows exiting the sow herds.


There were many variables in this process and much time and effort by breeding companies, universities, company nutritionists and not least the producers, have been taken to make this process as predictable as possible.


Variables may include disturbed growth patterns, infections, selection issues, reproductive disorders, physical disorders, nutritional issues, quality of semen, insemination process, stimulation patterns, age and weight. One of these factors may also be the occurrence of mycotoxins in gilt rations, which were known to have adverse effects on reproduction parameters and the immune system of the young animal among other things.


Furthermore, this was a variable that might be controlled very badly as even good-looking corn or feed could invariably be contaminated. Most mycotoxin formations occured during the growing period. Even if precautions were taken and a monitoring system was in place, mycotoxins would come in so-called " hotspots"  and might be present in one load of feed and not in another. Feed analysis programmes for mycotoxins, although better than doing nothing, often seemed like a waste of time and resources because symptoms might be seen in the herd despite analytical freedom in the monitoring protocol.


The mycotoxin, zearalenone, and a group of mycotoxins known as trichothecenes would especially affect reproduction adversely.


Zearalenone, a compound known to mimic estrogen in the body would induce swelling of the ovaries and uterus, often simulating heat. Gilts would show all visible signs of heat even before maturity and may even stand for service, yet the net result was a false heat.


Vulva vaginitis, mammary swelling, vulval swelling, anoestrus for up to 50 days and a lengthening of the cycle were other clear signs in gilts.


Other symptoms in sows and gilts included embryonic death, reduction of uterus or fetus weight, birth of weak and splay-legged piglets and vulval enlargements in piglets.


The implications might be that so-called "opportunity gilts" would in fact not be true opportunity gilts at all, and Heat No Serves (HNS) may in fact be falsely recorded and were not true heats at all.


Boars' semen was previously thought to be unaffected by ZEN, but motility, quantity and deformities of sperm were all known to be affected.


Trichothecenes, which included such compounds as DON (deoxynivalenol, or vomitoxin) T2, HT2 and approximately 150 plus other compounds, wreaked similar havoc. Feed intake may be affected and animal immune system may be compromised. Many of the toxic effects of trichothecenes stemmed from their capacity to inhibit DNA replication and protein synthesis.


Bloody diarrhea, severe dermatitis and hemorrhages were other symptoms commonly associated with this group of toxins but not necessarily the most economically dramatic as with such signs, it was clearly visible that there was a problem. Subtle problems may in fact be the worst problem associated with ZEN and the group of trichothecenes, in that a single false heat or missed service would have quite dramatic effects on the production pyramid. Such as a single return to service would incur US$6 to US$8 of extra feed cost and at least the semen cost which may vary from system to system and depending on the value of the animal.


Bearing all the above in mind, what measures should be taken in GDUs to ensure that this variable was eliminated from the GDU? The following may be a logical approach to the problem:

    • Screen suspect grain for presence of mycotoxins on a regular basis
    • Include a staff training session for signs of mycotoxins
    • Watch for telltale signs in gilts and act upon them with treatment or removal of the grains in question
    • Use a suitable product with a known ability to deactivate ZEN and trichothecenes, as an insurance policy to counteract mycotoxins in the feed

Economic implications of mycotoxins: What is the true value of a breeding gilt?


Much time and effort was spent raising our breeding gilts ultimately to become replacements within the herd. These efforts included vaccinations, added space allowances, selection, royalties and improved diets for these animals. Taking a slaughter pig as a base and calculating the added expense or value a breeding gilt represented, we could easily assume that a factor of 2-2.5 times the slaughter value or US$100-150 could easily be applied by the time all costs have been allocated.


Economic implications of a lost reproductive cycle due to mycotoxin contamination?


Many authors have written about this issue but often an exaggerated figure would be quoted to include many incidental costs, which did not necessarily reflect the direct loss incurred to modern integrated systems. To identify a true unequivocal cost, only clearly associated and actually incurred costs needed to be calculated. In the case of a lost cycle, only the feed cost and semen cost were true lost expenditures which would represent anywhere from US$10-12/animal.


Using Mycofix® Plus as an insurance policy to circumnavigate the problem profile!


Mycofix® Plus has been developed to offer a broad protection not only against aflatoxins, ochratoxins and fumonisins, but also zearalenone and the whole group of trichothecenes.


By combining adsorbing substances with enzymatic deactivation of toxins, Mycofix® Plus offers the most complete protection on the market today.


Marginal cost analysis for a GDU using Mycofix® Plus in all diets at 1kg/tonne of finished feed, based on a very conservative cost calculation, only one out of every 120-160 breeding gilts needed to be selected and brought into the herd to pay for the additional feed cost. However, the largest benefit was to be expected from the timely and unproblematic integration of breeding gilts in the herd. A single return to service would incur an additional US$10-12, which meant that Mycofix® Plus would pay for itself 10-15 times if used across the board in GDUs for this reason alone.






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