I am planning to do 4 or 5 behavior test on my respected groups after drug administration, I have to do test after every two weeks for about 8 weeks. I have eight groups and each group comprised of 30 animals. After behavior experiment i have to kill the animal for other studies. Can we select six or seven animal per group for each week experiment and kill them at the end. I have to do training in all the behavior experiments before trial. So, i need suggestion that is it fine to select 6-7 animals for each 2 weeks or not. Kindly explain if possible if we cant do it.
Yes, according to the CPCSEA guidelines of India, it is irrational to use more than 6 animals per group of rodents for obtaining statistically significant values. Ethics in biomedical research by ICMR also suggests use of minimum no.of group as far as practicable.
Hence, go ahead and wish you all the best.
The main problem with your experimental design is that the animals (n=30) in each group that are not used in a particular week will be getting older, and this will affect the results.
Thank you all for your comments:
My experiment plan is to evaluate the effect of drug on animal memory and depression with passing time that is 3, 6 and 9 weeks after drug administration and their effect on different molecular markers after each period of time.
So i decided to treat set of 30 animals to treat at each conc. of drug and selection of animals. after 3 weeks i select one third of animal do a battery of behavior test and sacrifice them after the testing. same will do at 6 and 9 weeks.
So, i just wanna confirm that this approach is fine as i have to train animals before trial.
Now that you have supplied more detail about your proposed study, the experimental protocol you intend to use appears to be fine.
Best wishes.
How about the control animals and baseline values for the biochemical markers?
I assume you also have a control group that does not receive the treatment but only vehicle administration. You should include this control group in the 3-6-9 weeks tests. The number of animals should be similar to the treatment groups.
Additionally, you should consider baseline values for the biochemical markers in naive rats without any behavioral testing and drug treatment, because behavioral testing or possible stress from the drug/vehicle administration may also impact your biochemical markers.
Take 8 animals since there will be the consideration of discarding those animals which are not responding within limits. As suggested for parameters to be assessed (Eg - Animal not reaching platform quadrant within 60 sec, even in 4rth day of training). 20 % more than minimum(6) needed for behavioral protocol i mean.
A major issue with randoms selection at each time point vs all of them, is that you will not be able to run repeated measures statistical analysis on them so you will have to analyze between individual variance as a possible effect. With smaller numbers, those may dramatically change your statistics, or you may have to standardize each response from the animals that are sampled more than once against their own scores/results
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