Analysis of the age-related changes
The results were grouped according to age as follows: 1) 15 pigs under six months of age; 2) 15 pigs between 6and 12 months of age; 3) 15 pigs between 12 and 18 months of age; 4) ten pigs between 18 and 24 months of age; 5) 12 pigs between 24 and 30 months of age; 6) nine pigs between 30 and 36 months of age; and 7) nine pigs over three years of age. The mean values for each age group were calculated, and an age-related analysis was conducted. Significant differences were confirmed using the one-way ANOVA with Tukey's post test using the Graphpad Prizm ver. 5.0 (Graphpad Software Inc., CA, USA).