We investigated the relationship between plasma L-carnitine concentration, at an internally synthesized level, and production performance in 4 strains of hybrid beef cattle and 5 strains of Holstein cows fed under normal conditions, they were sired by different strain bulls. There was no significant difference (P>0.05) in the plasma L-carnitine concentrations, which showed wide variations in both beef cattle and milk cows. Relationship between plasma L-carnitine concentration and body weight gain ratio in each strain of beef cattle tended to be positive regression, with no significance (P>0.05). There was no significant regression between the breeding objective factor and the plasma L-carnitine concentration in Holstein cows. Further verification of the relationship between plasma L-carnitine concentration and strain of cattle needs to be done in future.