[R] Statistic_help

[André Luis Neves]

Hi Everyone,

I have an experimental design that I'm confused about what model/approach I
should use to do the data analysis, and I would like to ask you for help as
there are many excellent statisticians and scientists in this group that
could help me to solve this problem.

The design is like this: I have 18 calves in the experiment, and all these
calves were divided into 3 groups with 6 calves in each group. The 6 calves
in group 1 were euthanized at the end of the first week (week 1) of birth,
the 6 calves in group 2 were euthanized after 3 weeks, and the other 6
calves in group 3 were euthanized after 6 weeks of birth. After the
euthanization, samples (different types of samples: digesta and content)
were collected from different gut regions (cecum, colon and rectum).
I should say that the calves in group 1 were only fed on whole milk, the
calves in group 2 were fed on whole milk during the first week after birth,
and after this, they were fed on whole milk and starter until the 3th week.
Finally, the calves in group 3 were also fed on whole milk during the first
week after birth, and then fed on milk and starter from the 2nd week to the
6th week after birth. After euthanizing the animals, I collected the
tissues and contents samples from each calf in the different groups, and
measured the quantity of four different species of bacteria to see the
establishment of these communities during the first weeks of life in calves.
The purpose of this study is to investigate the differences of the four
species of bacteria (in terms of quantity) among cecum, colon and rectum,
and also to see if the types of samples (content or tissue) are involved
in. Finally, I would like to know if the bacteria species found in the
different regions of the gut (cecum, colon and rectum) and in the sample
types (content or tissue)  are affected by the age (weeks after birth) and
by the type of food (as described before) that the calves received during
their life.

I should also say that this experiment was approved by the local animal
committee.

Thank you very much.

Andre

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