[R-sig-ME] Help with a mixed model analysis

[Rodrigo Junqueira Pereira]

Dear all.

I’m new on lme4 package and I would like to run a mixed model analysis on repeated measures longitudinal data. I have the following data.frame with the columns:

weight: weight of the animal;
sex: sex of the calf (2 classes);
age: age of the animal;
treatment: level of a protein supplement (levels: 0, 0.5, 1, 1.5, 2);
day: days to calving of the animal;

I would like to study the effect of the levels of the protein supplement (treatment) on the weight trend (quadratic regression) according to days to calving. However, is important to consider the additional fixed effects of the sex of the calf and the age of the animal (linear regression: intercept + slope) on the weight.

I have unequal number of replicates by treatment and unequal number of records by animal.

Could anyone help me with the model syntax on lme4 package?

Is it possible to get p-values for treatment comparisons?

——
Rodrigo.