I am struggling to interpret results from a few carbon dioxide trials I've run. The formulations being tested work as a preservative against yeast and mould. The set up is as such:
- Untreated animal feed
- Animal Feed treated with Formulation A (Formulation currently being used and thus the Control)
- Animal Feed treated with Formulation B (Formulation being tested to replace Formulation A)
All samples are in an enclosed bottle/environment and incubated at 25 degrees Celsius. I recorded the C02 readings every 3 to 4 days.
Findings:
- During the experiment it could be seen the C02 levels in the treated bottles were always lower than the Untreated bottles.
- Formulation A and B had very similar C02 readings throughout the experiment.
- When the Untreated feed reached 30 % C02 (the maximum limit for the detector I'm using), the treated samples were at less than 15 % C02 at the same point in time.
- Another thing to note is that there was almost no visible mould present even when the samples reached 30 % C02 (Experiments were run for about three weeks or so)
So my first problem is that I know that yeast and mould are not the only organisms that produce C02 as a byproduct of respiration so the C02 readings I'm getting isn't necessarily from my target organisms.
I'm not sure I can interpret it as the Formulations "killed the yeast and mould" in the samples and thus we have lower C02 values than the untreated bottles because I also tested some samples using normal micro plating and saw that there was only small differences in counts between all three types even after two weeks of contact time (the treated feed showed at most a 0.3 Log reduction in counts as compared to the untreated sample).
BUT I did also do zone of inhibition/disk diffusion testing for Formulation A and B against yeast and mould and they did give me fairly decent inhibition zones of around 1-2 cm
Would a better interpretation be that the formulations blocked the growth of the yeast and mould and thus gave lower C02 levels?
Or did they lower the respiration rates of the yeast and mould present in the feed thus leading to lower C02 levels?- Not sure if that's plausible though
Thanks!
Nirvana Jaganath The results clearly show some influence of both products on - most likely - the microflora - in your feed samples. I agree that you can not say that they killed yeast and mould.
Based on these data formulations A and B are equally (in)effective in reducing CO2 production.
In my view, you need more experiments/data before you can draw conclusions about the mechanism(s) behind the lower gas production and the consequences for the efficacy in storage of feed.
Do not forget that you tested apparently only one feed composition. It might well be that another feed composition might give another result.
Thanks C.A. (Kees) Kan
I have done the testing at three different dosages but all with poultry feed with the same result. I will be performing the test soon with silage samples and see how that works out. Thanks again
I have to ask, is there liquid in the bottles? Are they sealed bottles? if that is so, did you measure the amount of bicarbonate and dissolved carbon dioxide (dCO2) in the liquid? as the ppCO2 increases over the solution the liquid forms of CO2 will also increase in the liquid. The differences between samples might become more apparent if you account for those components. i.e. high ppCO2 might lead to bicarbonate accumulation if the final pH of the solution is high.
José Alberto Laporte Uribe The bottles contain dry poultry feed (the mositure is adjusted to 20 % with sterile distilled water but still appears dry and it is still a free flowing powder). The bottles are sealed airtight. There does seem to be some reaction when I add the treatments to the feed because on the first day of testing I test the C02 levels and the treated samples already show a readinf of around 0.3 % while the untreated sample is around 0.1 %. Environmental C02 levels (in our lab) is around 0.06-0.08%
it could be that carbonates have been formed?
I agree that the results suggest that your treatment affected growth, it might be, as the colleague has suggested, that with other diets you have a different result.
If this is not the case, and there is not shift in CO2 balance, your formulation might had inhibited yeast and mold growth.