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ARS Home » Plains Area » Miles City, Montana » Livestock and Range Research Laboratory » Research » Publications at this Location » Publication #340232
Title: Effects of fat and/or methionine hydroxy analog added to a molasses-urea-based supplement on ruminal and postruminal digestion and duodenal flow of nutrients in beef steers consuming low-quality lovegrass hay

Author
item LOPEZ, R - University Of Chapingo
item PULSIPHER, G - University Of Chapingo
item GUERRA-LIERA, J - Oklahoma State University
item SOTO-NAVARRO, S - Oklahoma State University
item BALSTAD, L - Oklahoma State University
item Petersen, Mark
item DHUYVETTER, D - Oklahoma State University
item BROWN, M - Oklahoma State University
item KREHBIEL, C - Oklahoma State University

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/8/2016
Publication Date: 6/3/2016
Publication URL: http://handle.nal.usda.gov/10113/5927808
Citation: Lopez, R., Pulsipher, G.D., Guerra-Liera, J.E., Soto-Navarro, S.A., Balstad, L.A., Petersen, M.K., Dhuyvetter, D.V., Brown, M.S., Krehbiel, C.R. 2016. Effects of fat and/or methionine hydroxy analog added to a molasses-urea-based supplement on ruminal and postruminal digestion and duodenal flow of nutrients in beef steers consuming low-quality lovegrass hay. Journal of Animal Science. 94:2485-2496. doi:10.2527/jas2015-0228.

Interpretive Summary: Energy intake of poor quality forage diets can limit grazing beef cattle gain. Fat as a concentrated energy source would be a logical addition to diets especially if it could be added to a conveniently delivered liquid molasses supplement. In addition supplemental nitrogen supplied as urea in a liquid molasses supplement maybe more efficiently utilized if amino acids were fed simultaneously. Five crossbred beef steers (initial BW = 338.6 ± 7.8 kg) fitted with ruminal and duodenal cannulas were used in an ( 5 × 5 Latin square design) experiment where every steer in a different time period received each of 5 different diets to evaluate the effects of methionine hydroxy analog (MHA) and/or yellow grease (fat) added to a molasses urea-based supplement on intake and characteristics of digestion. Steers were fed low-quality hay (long-stem lovegrass Eragrostis curvula: 3.3% CP, 76.8% NDF; DM basis) to appetite and supplemented with 0.91 kg/d (as fed) of 1 of 4 supplements treatments. Supplemental treatments were 1) control (no supplement, NC); 2) molasses urea liquid supplement (U); 3) U containing (as-fed basis) 1.65% MHA (UM); 4) U containing (as-fed basis) 12% fat (UF); and 5) U containing (as-fed basis) 1.65% MHA and 12% fat (UMF). Total and forage OM intake was increased with molasses-urea, decreased with MHA, and were not affected with fat supplementation. Total tract NDF digestibility increased with molasses-urea supplementation, and was less for fat added supplements. Total and microbial N flowing to the small intestine increased with molasses-urea supplementation. Although, total N flowing to duodenum was not affected, microbial N decreased, and nonammonia nonmicrobial N (NANMN) increased with fat supplementation. Extent of ruminal OM and NDF digestibility at 96 h increased with molasses-urea supplementation, but were not affected by either MHA or fat supplementation. Duodenal flow of total AA, essential AA, and nonessential AA increased with molasses-urea supplementation. Total and nonessential serum AA concentration decreased with molasses-urea supplementation. Total ruminal VFA concentration increased with molasses-urea supplementation, and was not affected by MHA or fat supplementation. In conclusion, adding MHA did not further improve the response to urea supplementation of cattle consuming low-quality forage and the inclusion of MHA in the supplement decreased forage intake. However, fat added to the supplement was used to increase energy intake without negatively affecting forage intake or characteristics of digestion.

Technical Abstract: Five crossbred beef steers (initial BW = 338.6 ± 7.8 kg) fitted with ruminal and duodenal cannulas were used in a 5 × 5 Latin square design experiment to evaluate the effects of methionine hydroxy analog (MHA) and/or yellow grease (fat) added to a molassesurea-based supplement on intake and characteristics of digestion. Steers were fed low-quality hay (long-stem lovegrass Eragrostis curvula: 3.3% CP, 76.8% NDF; DM basis) ad libitum and supplemented with 0.91 kg/d (as fed) of 1 of 4 supplements in a 2 × 2 + 1 factorial arrangement of treatments. Supplemental treatments were 1) control (no supplement, NC); 2) molassesurea liquid supplement (U); 3) U containing (as-fed basis) 1.65% MHA (UM); 4) U containing (as-fed basis) 12% fat (UF); and 5) U containing (as-fed basis) 1.65% MHA and 12% fat (UMF). Total and forage OM intake (kg/d and as % of BW) increased (P < 0.01) with molasses-urea, decreased (P = 0.04) with MHA, and were not affected (P = 0.61) with fat supplementation. Total tract NDF digestibility increased (P = 0.01) with molasses-urea supplementation, and was less (P = 0.01) for fat than for nonfat supplementation. Total and microbial N flowing to the duodenum increased (P = 0.01) with molasses-urea supplementation. Although, total N flowing to duodenum was not affected (P = 0.27), microbial N decreased (P = 0.01), and nonammonia nonmicrobial N (NANMN) increased (P = 0.01) with fat supplementation. Extent of in situ OM and NDF digestibility at 96 h increased (P = 0.01) with molasses-urea supplementation, but were not affected (P = 0.14) by either MHA or fat supplementation. Duodenal flow of total AA, essential AA, and nonessential AA increased (P = 0.02) with molasses-urea supplementation. Total and nonessential serum AA concentration decreased (P < 0.01) with molasses-urea supplementation. Total ruminal VFA concentration increased (P = 0.01) with molasses-urea supplementation, and was not affected (P = 0.14) by MHA or fat supplementation. Fat can be used in molasses-urea liquid supplements for cattle consuming low-quality forage to increase energy intake without negatively affecting forage intake or characteristics of digestion. However, adding MHA did not further improve the response to urea supplementation of cattle consuming low-quality forage. Conversely, the inclusion of MHA on urea supplement decreased forage intake.