Journal of Animal Science, Vol 74, Issue 6 1194-1201, Copyright © 1996 by American Society of Animal Science

JOURNAL ARTICLE

Effects of forage level on the comparative feeding value of supplemental fat in growing-finishing diets for feedlot cattle

R. A. Zinn and A. Plascencia
Department of Animal Science, Imperial Valley Agricultural Center, University of California, El Centro 92243, USA.

Ninety-six crossbred steers (316 kg) were used in a 135-d growth-performance trial to evaluate the comparative feeding value of yellow rease (0 vs 6%) in 10% forage vs 30% forage rowing-finishing diets. There were interactions between forage level and supplemental fat on ADG (P < 10), DM conversion (P < .05), diet NE (P < .10), longissimus muscle area (P < .01), fat thickness (P < 10), and percentage of retail yield (P < .01). Supplemental fat increased (8.5%; P < .10) marbling score, sufficient to move the average carcass grade from high Select to low Choice. With the low-forage diet supplemental fat did not affect (P > .10) ADG, but decreased (P < .01) retail yield (2.3%) and longissimus muscle area (5.6%). With the high-forage diet supplemental fat increased ADG (13.3%; P < .05) and longissimus muscle area (7.1%; P < .01) but did not affect (P > .10) retail yield. Differences in carcass fat were small and not affected by treatment (P > .10). The NEm and NEg values of yellow grease were 3.55 and 2.65 Mcal/kg, respectively, for the low-forage diet and 5.71 and 4.65 Mcal/kg, respectively, for the high-forage diet. Treatment effects on characteristics of ruminal and total tract digestion were evaluated using four Holstein steers (233 kg) with cannulas in the rumen and proximal duodenum. There were no interactions (P > .10) between forage level and supplemental fat on ruminal and total tract digestibility of OM, ADF, starch, lipid, and gross energy. Postruminal lipid digestibility averaged 65.5% and was not affected (P > .10) by forage level. The ME value of yellow grease was the same (6.94 Mcal/kg) for both the low- and high-forage diets. There was an interaction between supplemental fat and forage level on nonammonia N flow to the small intestine (P < .10), percentage of ruminal escape feed N (P < .05), postruminal N digestion (P < .05), and methane production (P < .10). With the low-forage diet, fat supplementation did not affect (P > .10) ruminal degradation for feed N and methane production. With the high-forage diet fat supplementation decreased ruminal degradation of feed N (19.0%; P < .05) and methane production (14.8%; P < .05). We concluded that supplementation of a 30% forage (alfalfa hay) finishing diet with 6% yellow grease will permit growth-performance similar to that of steers fed a 10% forage diet without supplemental fat. The improved performance may be attributed to increased diet energy density and positive associative effects on protein flow to the small intestine and decreased ruminal methane production.

This article has been cited by other articles:

				D. A. Chabot, C. D. Chabot, L. K. Conway, and S. A. Soto-Navarro Effect of fat supplementation and wheat pasture maturity on forage intake and digestion characteristics of steers grazing wheat pasture J Anim Sci, May 1, 2008; 86(5): 1263 - 1270. [Abstract] [Full Text] [PDF]

				B. W. Hess, G. E. Moss, and D. C. Rule A decade of developments in the area of fat supplementation research with beef cattle and sheep J Anim Sci, April 1, 2008; 86(14_suppl): E188 - E204. [Abstract] [Full Text] [PDF]

				S. P. Montgomery, J. S. Drouillard, T. G. Nagaraja, E. C. Titgemeyer, and J. J. Sindt Effects of supplemental fat source on nutrient digestion and ruminal fermentation in steers J Anim Sci, March 1, 2008; 86(3): 640 - 650. [Abstract] [Full Text] [PDF]

				Z. Yu, R. Garcia-Gonzalez, F. L. Schanbacher, and M. Morrison Evaluations of Different Hypervariable Regions of Archaeal 16S rRNA Genes in Profiling of Methanogens by Archaea-Specific PCR and Denaturing Gradient Gel Electrophoresis Appl. Envir. Microbiol., February 1, 2008; 74(3): 889 - 893. [Abstract] [Full Text] [PDF]

				E. Pavan, S. K. Duckett, and J. G. Andrae Corn oil supplementation to steers grazing endophyte-free tall fescue. I. Effects on in vivo digestibility, performance, and carcass traits J Anim Sci, May 1, 2007; 85(5): 1330 - 1339. [Abstract] [Full Text] [PDF]

				S. Hutchison, E. B. Kegley, J. K. Apple, T. J. Wistuba, M. E. Dikeman, and D. C. Rule Effects of adding poultry fat in the finishing diet of steers on performance, carcass characteristics, sensory traits, and fatty acid profiles J Anim Sci, September 1, 2006; 84(9): 2426 - 2435. [Abstract] [Full Text] [PDF]

				T. D. Maddock, M. L. Bauer, K. B. Koch, V. L. Anderson, R. J. Maddock, G. Barcelo-Coblijn, E. J. Murphy, and G. P. Lardy Effect of processing flax in beef feedlot diets on performance, carcass characteristics, and trained sensory panel ratings J Anim Sci, June 1, 2006; 84(6): 1544 - 1551. [Abstract] [Full Text] [PDF]

				C. R. Krehbiel, J. J. Cranston, and M. P. McCurdy An upper limit for caloric density of finishing diets J Anim Sci, April 1, 2006; 84(13_suppl): E34 - E. [Abstract] [Full Text] [PDF]

				D. J. Gibb, F. N. Owens, P. S. Mir, Z. Mir, M. Ivan, and T. A. McAllister Value of sunflower seed in finishing diets of feedlot cattle J Anim Sci, September 1, 2004; 82(9): 2679 - 2692. [Abstract] [Full Text] [PDF]

				E. E. D. Felton and M. S. Kerley Performance and carcass quality of steers fed different sources of dietary fat J Anim Sci, June 1, 2004; 82(6): 1794 - 1805. [Abstract] [Full Text] [PDF]