Abstract：In the present investigation an optimized semi-quantitative RT-PCR was applied to detect the PR-39 gene expression difference in femur marrow of piglets at different ages and weaning by using 18S rRNA as inner marker. Samples were taken at birth ,3 ,14 , 23 ,28 days of age respectively. The results showed that age affected PR-39 mRNA levels in femur marrow significantly (P < 0.05), the expression of PR-39 mRNA was the lowest at birth, then increased remarkably at 3 days of age, but the expression at 14 d-old was lower than that of 3 days (P < 0.05),and it was increased thereafter. Weaning affected PR-39 mRNA levels significantly also (P < 0.05). Weaning decreased the PR-39 mRNA levels at the same day.
