Table 5.

Level of milk production × physiological period interaction (P < 0.05) for serum metabolites of beef cows

Measurement	Milk production1			SEM
	Low	Mod	High
NEFA, µmol/L
Prebreeding	609ax	710bx	762bx	25
Breeding	436ay	439ay	455ay	21
BHB2, µmol/L
Prebreeding	227ax	233ax	225ax	11
Breeding	237ax	256ax	253ay	11
Insulin, ng/mL
Prebreeding	0.27ax	0.24ax	0.24ax	0.03
Breeding	0.39ay	0.30bx	0.36aby	0.03

^a,bMeans with different superscripts differ among milk production groups (P ≤ 0.05).

^x,yMeans with different superscripts differ between physiological periods (P ≤ 0.05).

¹Milk production groups: Low (6.57 ± 1.21 kg), Mod (9.02 ± 0.60 kg), or High (11.97 ± 1.46 kg).

²Beta-hydroxybutyrate.