TomaHawk iL Zn Trial- The Healthy and Natural Feeding of Cattle

The selection of natural feed additives for calves is growing. Traditionally, ionophores and medicated feed additives appealed to calf growers in an attempt to increase efficiency, growth, and to ward off disease. More recently, as we have learned more about the Gut MicroBiome and its impact on animal performance- prebiotics, probiotics, and postbiotics technologies are now being utilized.

Peer reviewed scientific literature suggests that the Gut Microbiome and the Immune System can be modulated by biologically active feed additives. The decision to use natural feed additives should be based on scientific research, product effectiveness and return on investment.


Tomahawk iL Zn

Tomahawk iL Zn is a natural feed additive for cattle that consists of yeast culture, yeast cell wall, yeast extracts, bacillus subtilis, yucca  and zinc methionine. This product was evaluated for effectiveness and economic return by a World Renowned Veterinary Group in the western United States.


Experimental Design

In a large-scale trial conducted on a commercial calf grower site, day-old dairy and dairy-crossbred steer and heifer calves at ultra-high risk (UHR) of developing BRD were randomly divided into 2 experimental groups. A total of 1,374 calves were included in the trial.

The Control Group received their normal milk and feed ration, with nothing additional added.

The second group, TomaHawk iL Zn, received the same rations and in addition received 20ml of Tomahawk upon arrival at the calf ranch. Calves were fed 3ml/feeding (total of 6ml/day) during small hutch phase (average of 32 days) and 6ml/head/day of Tomahawk iL Zn in their grain during the large hutch phase (average of 54 days).

Outcome variables were measured from arrival to exit at 240 days (shipping as a feeder, culling, or death) to evaluate the effects of each feeding program on animal health and performance. Statistical analysis was used to determine the probability of whether differences in outcome were due to differences in the feeding programs or by random chance.


Economic Value of Feeding TomaHawk iL Zn


TomaHawk iL Zn vs Control

Overall Mortality


Program Cost


Interest Cost


Net Economic Advantage


From arrival to shipment, there was an economic advantage of $5.34/animal in the TomaHawk iL Zn group compared to the Control group.



Outcomes shown in the chart below are a comparison of the TomaHawk iL Zn treatment group compared to the Control group.




Initial UF (BRD) Treatment



1st UF Treatment Relapse



Initial Gastrointestinal Disease



Overall Mortality

3.56 %


Total Outs (Mortality + Culls)



TP <5.60 g/dl: Total Outs






Feed intake




Initial UF (BRD) Treatment- first treatment given for a fever, most likely to an animal with BRD. A reduction in this number is significant as it indicates that less animals are getting sick.  

1st UF Treatment Relapse- sick calves that need a second round of treatments. A reduction in this number indicates that the first treatment is more effective.

Initial Gastrointestinal Disease- calves treated for Gastrointestinal Disease. A reduction in this number would mean less animals are getting sick and having issues in their gut.

Overall Mortality- calves that die and are removed from the trial. A reduction in this number means that less animals are getting sick, and more animals that do receive treatment actually recover.

Total Outs (Mortality + Culls)- sum of deads and culls. A reduction in this number means that less animals die, and less are deemed unfit and culled.

TP <5.60 g/dl: Total Outs- total serum protein under 5.6 g/dl is failure of passive transfer, many of these animals do not make it long term and die or are culled. A reduction in total outs in the group of animals with failure of passive transfer means a larger percentage of them thrive, live a productive life, and do not die or perform poorly enough to be culled. 

Feed intake- amount of feed eaten. An increase in this number indicates that the calves are eating better.


“A picture is worth a thousand words”


Calf Distinction/MicroBasics

Each calf rearing system is faced with different challenges. Visit with your veterinarian and nutritionist about the benefits of a natural feed additive.

At Calf Distinction/MicroBasics we believe that the producer should have options that include effective natural alternatives to conventional ionophores and antibiotics. Our product ingredients are researched and set us apart from others on the market in effectiveness and return on investment. You can find them in the Calf Distinction Store.


Written by: Mariah Gull, M.S.

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