Through the years,
additional testing has been done as part of on-going product
development and improvement efforts. Now, other feed companies are
marketing methoprene-containing products. To ensure we provide the
best methoprene products in the industry, Alliance Nutrition’s
research staff continuously tests their own field-proven IGR
Minerals® products along with competitor products.
In a research trial, competitors’
methoprene products were obtained from normal marketing channels.
Methoprene levels were analyzed initially and at monthly intervals
up to six months. Samples were stored under typical farm storage
conditions. Test results from 1999 to 2000 are given in Table 1.
The label level and the actual amounts of methoprene contained in
the products upon acquisition and after six months of storage are
shown in Table 1.
Also, noted are percentage differences which enable valid
comparisons to be made among products due to the differing
methoprene levels shown on the labels.
Methoprene-containing products provide
effective reduction in the horn fly population when the product:
• Provides sufficient levels of
methoprene
• Is consumed at the target intake
• Is consumed on a regular basis
Methoprene must be fed at a rate of
22.7 to 45.4 mg per 100 lb of body weight per month. Most
methoprene products are formulated to the mid-point of this range
based on the target consumption rate. This allows for some
variation in manufacturing and intake. When formulated at the
“mid-point,” the methoprene level can drop to 70% of level amount
and still be effective.
Alliance Nutrition’s research showed
only 10 out of 28 competitors’ products contained over 70% of the
label amount of methoprene when received. Products containing less
than 70% of the stated label amount are unlikely to provide
acceptable horn fly control. In contrast, all Alliance Nutrition
products tested contained over 90% of the label amount.
While a product may provide an
acceptable level of methoprene, scrutiny of the label is needed.
For instance, Brand G appears to be acceptable; however, label
inspection indicates this product has been formulated to provide
22.7 mg of methoprene per 100 lb of body weight per month when
consumed at the recommended rate. The formulation of this product
does not allow any margin for loss in manufacturing, changes in
methoprene levels over time, or variation in intake. Thus, even
with 86% of the label amount present initially, this product is
not likely to provide acceptable horn fly control.
The stability of methoprene is
affected by a number of factors and is reflected in a decrease in
the concentration over time. Information presented in
Table 1 shows 15
of the 28 products tested lost 30% or more of the methoprene
present initially. Of the remainder, seven of the products
contained less than 70% of the label amount of methoprene when
received. In contrast, Alliance Nutrition’s products remained
above effective levels for the duration of the test.
The combination of low initial
methoprene levels and large losses during typical storage
conditions make the competitors’ products tested highly
questionable in their ability to provide acceptable horn fly
control. Failure of these products to effectively control horn fly
populations is due to the lack of methoprene present, not to
methoprene resistance. To date, no known case of resistance to
methoprene has been documented.
Comparison of the
results of Brand A in 1999 versus 2000 shows little or no
improvement in either the level of methoprene present initially or
in the ability to maintain methoprene levels over time. For Brand
B, there was little change in the average amount of methoprene
found initially, but an apparent improvement in the stability of
the methoprene over time was made. Overall, the competition
improved only slightly from 1999 to 2000.
At the time tests were conducted in
1999, Alliance Nutrition researchers were developing the OptiCor®*
versions of the IGR Minerals. In those tests, three bags of each
Alliance Nutrition IGR Mineral products were placed in storage and
sampled monthly for six months. Results are shown in
Table 2.
These mineral products all exhibit the
key attributes desired in a methoprene containing product:
• Methoprene is present in the
quantities stated on the label
• Methoprene is stable over time,
with losses averaging 10% or less over a six-month period
