title: Effects of molasses and crude glycerol combined in a liquid supplement on ruminal fermentation in beef steers consuming bermudagrass hay.
abstract: Two experiments were performed to evaluate the effects of 1) increasing supplementation doses of a 50:50 (as-fed) liquid supplement of molasses and crude glycerol (M:G) on ruminal fermentation parameters and blood urea nitrogen (BUN) in beef steers consuming Tifton 85 bermudagrass ( spp.) hay and 2) different proportions of molasses and crude glycerol in a liquid supplement on in vitro fermentation and gas production kinetics. For Exp. 1, 8 ruminally cannulated, Angus-crossbred steers were used in a duplicated 4 × 4 Latin square design, had ad libitum access to Tifton 85 bermudagrass hay, and were randomly assigned to 1 of 4 treatments: 1) CTRL, no supplementation; 2) SUP1, 0.45 kg/d (as fed) of 50:50 M:G; 3) SUP3, 1.36 kg/d (as fed) of 50:50 M:G; and 4) SUP5, 2.27 kg/d (as fed) of a 50:50 M:G. For Exp. 2 in vitro batch cultures were conducted to test the same treatments from Exp. 1 and effects of different proportions of a M:G mixture (100:0, 75:25, 50:50, 25:75, and 0:100) when added to a hay substrate simulating the proportions of hay and liquid supplement used in SUP5. In Exp. 1, increasing doses of liquid supplement linearly decreased ( < 0.001) concentrations of NH-N, BUN, and acetate molar proportions, whereas propionate ( = 0.002) and butyrate ( < 0.001) molar proportions increased linearly. Treatment × time interactions were observed for ruminal pH ( < 0.001), where the greatest decrease was observed at 3 h postfeeding for animals consuming SUP5 (from 6.82 at 0 h to 6.32 at 3 h). In Exp. 2, decreases in acetate molar proportions ( < 0.001) and increases ( < 0.001) in propionate and butyrate molar proportions were also observed for either increasing doses of a 50:50 mixture or increasing proportions of glycerol in the mixture. Total VFA and in vitro organic matter digestibility were increased linearly ( < 0.001) as doses of a 50:50 mixture increased. Increasing doses of 50:50 M:G to growing beef heifers consuming bermudagrass hay caused a shift in VFA profile toward increases in propionate and decreases in acetate molar proportions. This was also confirmed in vitro, as the proportions of crude glycerol increased in a molasses:crude glycerol mix. Thus, molasses and crude glycerol combined seem to be useful to enhance performance in growing cattle consuming forage-based diets.
authors.forename: F M
authors.initials: FM
authors.lastname: Ciriaco
authors.forename: D D
authors.initials: DD
authors.lastname: Henry
authors.forename: V R G
authors.initials: VR
authors.lastname: Mercadante
authors.forename: T M
authors.initials: TM
authors.lastname: Schulmeister
authors.forename: M
authors.initials: M
authors.lastname: Ruiz-Moreno
authors.forename: G C
authors.initials: GC
authors.lastname: Lamb
authors.forename: N
authors.initials: N
authors.lastname: DiLorenzo
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002417:Cattle / Q000502:physiology*; D031744:Cynodon; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004063:Digestion / Q000187:drug effects; D005260:Female; D005285:Fermentation / Q000187:drug effects; D005990:Glycerol / Q000494:pharmacology*; D008297:Male; D008965:Molasses; D018515:Plant Leaves; D011897:Random Allocation; D012417:Rumen / Q000378:metabolism
chemical_list: D005990:Glycerol