I study the effects of probiotic feed additives on the growth performance of broiler chickens. How do I calculate ADG & ADFI from 0-33 days given the data of the two parameters per stage of growth (booster, starter, and finisher)?
It depends, whether you want to include all animals started or to correct for those that died during the growout period.
C.A. (Kees) Kan I have accounted the mortality using broiler days (head count/pen * days per stage). Initially, the formula I used was
Overall ADFI 0-35 = SUM(Intake D10 to D35) / SUM (Broiler Days D10 to D35)
I used MS Excel as the raw data is encoded there.
Dear Kyle, I do not understand that you calculate ADFI 0-35 by using the data from 10-35. Mistake or intention ? Originally you asked about 0-33, so be consistent.
Apologies for the typographical errors, Dr. Kan. What I meant to type was 0-33.
Oh. D10 is merely a variable for the sake of presenting the equation. The data I possess are from Day 0 - 33. Again, apologies.
The simple solution might be: take the sum of feed intake per bird over all three periods and total weight increase per bird over the three periods and divide them by 33. If you have males and females separated, you may calculate data per sex. If not you should hope or be certain that you had equal numbers of both sexes in all treatment groups.
Dear C.A. (Kees) Kan
Please how can we correct for those that died during the growout period?. we can measure their weight on the day of their death but how can we calculate their feed intake ?
Best regards
Dear Bella Raja
You cannot measure feed intake unless you have housed them separately, which is not to be advised. Thus you have to make assumptions.
In my opinion this is only worthwhile, if you are making comparisons between treatments in one experiment and if there are noticeable differences in mortality between treatment groups in the later stage of the growout period.
Then my option would, be to take the FCR over the whole period and the body weight of the dead animals and from there calculate the assumed amount of feed consumed in the period before their death. This can then be subtracted from the total feed intake of the experimental unit in question and from there the corrected FCR for this unit.
Early in the growing period feed consumption will be (much ) less and also I would calculate on basis of bodyweight gain, but the importance of correction on the end result will probably be also not large.
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