Effects or roughage source and level on intake and performance by finishing heifers



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Texas Tech University


Twelve medium-framed beef heifers (average BW = 189 kg) were used in three simultaneous, 4 x 4 Latin square intake trials to evaluate the effects of dietary NDF supply from four roughage sources on NEg intake. Steam-flaked com-based diets {13% CP) containing alfahfa hay (ALF), sorghum sudan hay (SS), wheat straw (WS), or cottonseed hulls (CSH) were fed in each Latin square at 5, 10, or 15% of dietary DM. Within each roughage concentration, NDF from roughage (NDFR) accounted for the majority of variation in NEg intake per unit of metaboUc BW (NEI, kcal/kg of BW) among the roughage sources. Coefficients of determination (r ) for NEI regressed against NDFR were r^ = 0.91 (P = 0.048), r^ = 0.76 (P = 0.127), and r^ = 0.92 (P = 0.039) within the 5, 10, and 15% roughage concentrations, respectively. Across all roughage concentrations, the r was 0.68 (P = 0.001), and averaged across the three roughage concentrations, NEI was greater (P < 0.10) when heifers were fed CSH, SS, or WS than when fed ALF.