Effects of base ingredient in cooked molasses blocks on intake and digestion of prairie hay by beef steers

Twelve steers (332 kg) were used in three simultaneous 4 x 3 incomplete Lat in squares to evaluate effects of beet molasses (BEET), cane molasses (CANE ), or concentrated separator by-product (CSB) as base ingredients in cooked molasses blocks on intake and digestion of prairie hay and ruminal charact eristics. All steers had ad libitum access to prairie hay (5.9% CP and 69.4 % NDF; DM basis). The four experimental treatments included a control (no s upplement) and three cooked molasses blocks, based on BEET, CANE, or CSB, f ed daily at .125% of BW (.42 kg/d as-fed,.13 kg/d CP). Forage OM, NDF, and N intakes; digestible OM, NDF, and N intakes; and total tract OM and N dige stibilities (percentage of intake) were greater (P < .05) for steers fed co oked molasses blocks than for control steers. Total tract OM digestibility was greater (P less than or equal to .06) for steers fed BEET blocks (54.0% ) than for those fed CSB (52.1%) or CANE blocks (52.2%). Digestion of NDF w as greatest (P < .05) for steers fed BEET blocks (51.9%) and tended to be g reater (P < .07) for steers fed CANE (49.3%) or CSB blocks (49.3%) than for control steers (46.9%). Ruminal ammonia concentrations were greater (P < . 05) for steers fed cooked molasses blocks (.89 mM) than for control steers (.21 mM); this was primarily due to increases to 4.6 mM at 2 h postfeeding for steers fed blocks. Concentrations of total VFA in ruminal fluid were gr eater (P < .05) for steers fed BEET (92.7 mM) and CSB (88.1 mM) blocks than for control steers (80.3 mM), whereas concentrations for steers fed CANE b locks were intermediate (85.4 mM). Steers supplemented with cooked molasses blocks had greater molar percentages of butyrate than did control steers, particularly shortly after feeding. In summary, supplementation with cooked molasses blocks increased forage intake and digestion. The three base ingr edients elicited similar responses, although steers fed BEET had slightly g reater OM and NDF digestibilities than those fed CANE or CSB.