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The objective was to determine the effect of stockpiled forage type and protein supplementation on VFA production, serum metabolites, and heifer BW. Over 2 yr, spring-born, crossbred heifers (n = 45) were stratified by BW at weaning and randomly assigned to 1 of 3 forage treatments: 1) endophyte-infected tall fescue (TF; Festuca arundinacea), 2) big bluestem (Andropogon gerardi Vitman) and indiangrass (Sorghastrum nutans L.) combination (BI), or 3) switchgrass (SG; Panicum virgatum L.). Forage treatments were then randomly assigned to receive 1 of 2 supplement types: 1) 0.68 kg·heifer-1·d-1 of dried distiller's grains with solubles (DDGS; 28% CP, 74% RUP, and 88% TDN) or 2) 0.22 kg·heifer-1·d-1 of blood meal and fish meal (BF; 72.5% CP, 67.5% RUP, and 69.5% TDN), resulting in a 3 × 2 factorial arrangement of treatments. Treatments were initiated every year in January and terminated in April at the onset of a 60-d breeding season. Body weights and serum samples were collected approximately every 28 d from initiation of grazing until breeding. Serum glucose concentrations were greater (P = 0.05) for heifers grazing SG. Circulating NEFA concentrations were greater (P = 0.04) in TF heifers. Serum urea N (SUN) was not influenced (P = 0.37) by forage type. Ruminal acetate concentration and acetate:propionate ratio were greater (P = 0.04) in heifers grazing SG pastures. Heifer BW change from January to February and overall BW change were greater (P < 0.01) for TF heifers. However, BW change from March to April was not different (P = 0.84) among forage types. Serum glucose and SUN concentrations exhibited (P < 0.05) supplement type × sampling time interactions. Ruminal acetate tended to be greater (P = 0.09) and butyrate concentrations were greater (P < 0.01) for BF-supplemented heifers. The acetate:propionate ratio was not influenced (P = 0.15) by supplement type. Supplement type did not influence (P > 0.13) BW or BW change from January to February and January to April; however, heifers fed DDGS gained (P = 0.03) more BW from March to April. Heifer BW change from February to March exhibited (P < 0.05) a forage type × supplement interaction with BF heifers gaining more BW on BI pastures than DDGS heifers. Overall, developing heifers on low-quality native forages initially delayed BW gain; however, heifers seemed to quickly adapt to the lower-quality forage, resulting in similar BW gains in March and April. [ABSTRACT FROM AUTHOR]