Changes in concentrations of plasma metabolites and insulin-like growth factor-1 after feeding in Japanese Black and Japanese Shorthorn cattle

The aim was to characterize the changes of plasma component concentrations after feeding in Japanese Black (B) and Japanese Shorthorn (S) cattle. Eight females, five B and three S, with a mean bodyweight (standard deviation) of 282.0 (20.3) kg were selected and supplied with only water for 28 h after feeding. Blood was taken from the jugular vein at 4‐h intervals for 32 h after feeding. Metabolite (cholesterol, CL; glucose, GLU; nonesterified fatty acid, NEFA; triacylglycerol, TG; total protein, TP) and insulin‐like growth factor‐1 (IGF‐1) concentrations in plasma were measured. In both breeds GLU tended to decrease linearly with a similar slope. Differences between the initial mean NEFA at 4 h after feeding (Start) and that at 24 h after the start (End) were significant in both breeds, but S increased significantly more than B at and after 8 h from the Start. The TG in S tended to change more than in B, and CL and IGF‐1 in both breeds changed continuously at similar levels. The TP in B tended to decrease more slowly and be lower than S. The change in NEFA, especially, suggests that nutritional status sensitively reflects genetic background.