Table 5.

Plasma concentrations of glucose, IGF-1, insulin, urea N (PUN), and nonesterified fatty acids (NEFA) of Nellore heifers offered free choice access to warm-season grass hay and receiving trace mineral supplement (TM), sugarcane molasses cooked block (LMB), pair-fed protein supplement (PSPF), and a commercial protein supplement (PS) from day 0 to 45 (n = 100 heifers; five heifers/pen; five pens/treatment)¹

	Treatment1					P-value
Plasma2	TM	LMB	PSPF	PS	SEM	Treatment × day	Treatment
Glucose, mg/dL	83.6a	90.9b	96.1b	95.5b	3.54	0.88	0.08
IGF-1, ng/mL	33.1	35.1	34.5	37.8	2.6	0.95	0.61
Insulin, μIU/mL	7.11	6.69	7.02	6.97	0.474	0.78	0.93
PUN, mg/dL	9.6a	11.1b	11.9b	11.1b	0.40	0.12	0.005
NEFA, mEq/L	0.148	0.153	0.173	0.154	0.023	0.87	0.78

^a,bWithin a row, means without a common superscript differed (P ≤ 0.05).

¹TM = a complete vitamin/trace mineral mix supplement offered in a loose meal form (66.6% of LMB supplement DMI); LMB = free choice access to a low-moisture, cooked sugarcane molasses-based block; PSPF = protein supplement offered in a loose meal form and pair-fed to achieve similar supplement intake of DM, TDN, and CP of LMB heifers; PS = a commercial protein supplement offered in a loose meal form at 0.2% of BW (DM basis).

²Plasma concentrations of glucose, IGF-1, insulin, PUN, and NEFA were included as covariates (P ≤ 0.02). Means shown above represent the average plasma concentration of each respective parameter obtained on day 24 and 45.