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Effect of grazing legumes or grass forages with or without corn supplementation on animal performance and meat quality of forage-finished beef

EFFECT OF GRAZING LEGUMES OR GRASS FORAGES WITH OR WITHOUT CORN SUPPLEMENATION ON ANIMAL PERFORMANCE AND MEAT QUALITY OF FORAGE-FINISHED BEEF. A. Wright, J. Andrae, M. Miller, P. Gunter, C. Fernandez Rosso, E. Pavan and 1Clemson University, Clemson, SC 29634 Angus x Hereford steers (n = 32) were used in a 2-yr study (2011 and 2012) to examine forage type (legume species, alfalfa and soybeans LG vs. grass species, tall fescue and sudangrass, GR) and daily corn supplementation (0%, NS, vs. 0.75% BW, CS) on animal performance and carcass quality. Steers grazed (May-August) for a total of 105 d when finished to an equal time endpoint. Upon completion of the finishing period, steers were slaughtered and carcass data were collected. Steaks (2.5 cm thick) from the longissimus dorsi muscle (LM) were collected for measurement of proximate analysis and tenderness after different postmortem aging times (2, 4, 7, 14, 28 d). Data were analyzed in a mixed model using a 2x2 factorial arrangement of treatments. Steer was the experimental unit and year included as a random effect. Corn supplementation (CS) increased (P < 0.05) average daily gain (ADG), hot carcass weight (HCW), dressing percentage (DP) and tended (P < 0.06) to increase fat thickness at the 12th rib (FT). CS also increased (P < 0.05) yield grade (YG) and tended to increase (P < 0.07) quality grade (QG). In terms of forage, LG increased (P < 0.05) DP and HCW, with a tendency to increase ADG (P < 0.06). CS resulted in lower (P < 0.05) concentrations of CLA c9t11 and n-3 FA. Steers receiving CS had a higher (P < 0.05) n-6:n-3 ratio (3.1 vs. 2.4), but both are lower than the 4:1 ratio recommend by health officials. Grazing GR increased (P < 0.05) saturated FA due to greater (P < 0.05) concentrations of stearic (C18:0) acid. LG forage increased calcium content of the LM. Tenderness was only affected (P < 0.05) by postmortem aging. Grazing legumes during finishing improves HCW and DP, and tends to improve ADG. Corn grain supplementation to grazing steers improved animal performance while not negatively impacting the nutritional qualities of the meat. Introduction: Forage-finished beef remains a niche market in the U.S., but it continues to grow each year in terms of consumer demand. This is related to perceived human health and environmental benefits (low-input production systems). There are also studies (Franzluebbers, 2007 and Russelle et al., 2007) suggesting economic and environmental benefits when crops are integrated with forage based livestock systems. Forage finishing beef with our without corn supplementation, provides an opportunity for producers to integrate livestock and crops. The primary human health benefits associated with finished beef when compared to feedlot-finished beef are less saturated fat, improved n-6:n-3 fatty acid ratio, and a higher percentage of conjugated linoleic acids (CLA) (French et al., 2000; Pavan et al., 2008; Fincham et al., 2009.) Duckett et al. (2009) reported that meat from forage compared to concentrate diets had higher concentrations of ß-carotene, vitamin E, B-vitamins, and some minerals. Based on the current research, it can be concluded that forage-finished beef has apparent health benefits; however, much of the research existing on this topic primarily compares beef from concentrate diets to all forage diets. Few research studies have been conducted on the effects of forage species on animal performance and meat quality. The majority of studies that do exist used mixed species (legume and grass) pastures and indicated that pastures with legumes result in a higher ADG and at times higher finish weights (Dierking et al., 2010; Golding et al., 2011). Similarly there is limited information that exists on whether or not a moderate amount of corn supplementation (≤1% of BW/hd/d) affects animal performance and meat quality. In general the studies (Del Campo et al., 2008; Latimori et al., 2007; Roberts et al., 2009) that evaluated corn supplementation have all shown an increase in ADG and improvements in carcass quality. The objective of this study was to examine the effect of forage type and corn supplementation on animal performance and meat quality. We hypothesized that legume would improve animal performance and carcass characteristics when compared to grass. We also hypothesized that corn supplementation would improve animal performance and carcass characteristics compared to steers receiving no supplementation. Materials and Methods: All procedures involving animals were approved by the Clemson Animal Care and Use Committee. Angus x Hereford steers were used in a 2 year study (year 1: n=16, year 2: n=16) to evaluate the effects of forage type (legume species, alfalfa and soybeans, LG vs. grass species, tall fescue and sudangrass, GR) and daily corn supplementation (0%, NS, vs. 0.75% BW, CS) on animal performance and meat quality. Each year steers were blocked by weight, and randomly assigned to 1 of 4 treatments. The four treatments were LG:CS, LG:NS, GR:CS, and GR:NS. Steers grazed for 105 d (May-August) and were finished to an equal time endpoint. Steers were moved based on forage quality and availability and had no competition for feed due to a very low stocking density (2head/ha). All steers grazed perennial forages prior to grazing annuals (i.e. alfalfa to soybean and tall fescue to sudangrass). The daily CS supplement consisted of cracked corn + 150mg of monensin. Steers were weighed every 28 days, and CS amounts were recalculated. Prior to the trial all steers grazed winter rye pasture followed by non-toxic tall fescue. During this period, steers were trained to Calan gate feeders (American Calan Inc., Northwood, NH). Each forage species had two replicate pastures with CS and NS steers contained in all pasture replicates. The Calan gates were used to prevent the NS steers from having access to CS while allowing both groups to graze the same paddock. Animals were transported (130km) to Brown Packing Co. in Gaffney, South Carolina fasted overnight, and slaughtered the next morning at which point HCW was taken for each animal. Within 24h after slaughter carcass characteristics including maturity, fat thickness at the 12th rib, 12th-rib longissimus muscle (LM) area, kidney pelvic heartfat (KPH), marbling score, and USDA quality grade and yield grade (calculated) were evaluated by a trained professional. The 6-12 rib section was removed from the left side and transported to Clemson, SC for fabrication. At 48 h postmortem the entire LM was removed from the rib. All external fat and connective tissue was removed from the LM. Steaks (2.5 cm thick) from LM were obtained for proximate analysis and tenderness after different postmortem aging times (2, 4, 7, 14, 28 d). Proximate analysis from freeze-dried steaks consisted of minerals and CP analysis at the Clemson Ag. Service Laboratory, lipid profile and cholesterol using Gas Chromatography (GC), and fat-soluble vitamins using High Pressure Liquid Chromatography (HPLC) (Duckett et al., 2009). All tissue values were reported on a wet basis. Data were analyzed in a mixed model using SAS. Least square means were compared when a significant F-value (P < 0.05) was found. Data were analyzed using a 2x2 factorial arrangement of treatments with forage (LG or GR), grain (CS or NS), and forage x grain interaction in the model. Year was included as a random effect, and steer was the experimental unit. Results and Discussion: There were no forage-type by corn supplementation interactions so the main effects are presented. Steers grazing LG had a (P < 0.05) greater hot carcass weight (HCW) and higher dressing percentage (DP) compared to steers grazing GR (Table 1). LG tended (P < 0.06) to improve ADG compared to GR (0.8kg vs 0.7kg). Steers on CS had higher (P < 0.05) rates of gain, which may be attributed to the differences in energy density between the diets. One other benefit of corn supplementation to steers grazing forage is the potential to increase stocking rates due to the associative effects and/or decreased forage intake (Horn et al., 2005). Steers receiving corn supplementation also had greater (P < 0.05) DP, HCW, and fat thickness at the 12th rib (FT). There was a trend (P < 0.07) for steers supplemented with corn to have an improved QG. Sixty-nine percent of the supplemented steers graded USDA Choice compared to fifty-three percent of non-supplemented. The proximate analysis of the longissimus dorsi (LM) muscle indicates that there was no major forage effect on fatty acid composition; however, steers grazing GR had a slightly larger (P < 0.05) concentration of saturated fat due to higher (P < 0.05) levels of stearic acid (C18:0). CS reduced (P < 0.05) the concentration of polyunsaturated n-3 FA within the LM. This lead to an increase (P < 0.05) in the n-6:n-3 FA ratio for steers supplemented with corn; however, this increased ratio for CS compared to NS (3.1 vs. 2.4) is still within the ideal ratio (≤4:1) for human health (Okuyama, 2001). CS also decreased (P < 0.05) LM concentrations of the c9t11 isomer of conjugated linoleic acid (CLA), the FA reported to possess anti-carcinogenic properties (Bhattacharya et al., 2006). It is important to note that when c9t11 CLA was adjusted by the total lipid, there was no difference in concentration. There was also no CS effect detected for saturated, monounsaturated, or n-6 fatty acids. Forage type had no effect on cholesterol or mineral content. CS also had no impact on LM cholesterol, but CS did reduce (P < 0.05) the LM concentration of calcium, which is consistent with the research of Duckett et al. (2009). Both studies found a 25% reduction in calcium, suggesting that even a limited amount of CS can have the same impact on calcium as CONC. Though differences in calcium were detected, it is important to note that beef is not generally regarded as a good source of calcium. Based on the results of the Warner-Bratzler shear force test, tenderness was only impacted (P < 0.05) by postmortem aging and not by dietary treatment. This is agreement with other research (Roberts et al., 2009 and Kerth et al., 2007) that concluded corn supplementation had no impact on tenderness. This two-year study suggests that steers grazing legumes will finish with a larger HCW and a higher DP. Steers grazing legumes have a tendency to gain weight faster. Steers receiving corn supplementation at 0.75% BW per day, will have more rapid BW gains, larger HCW, FT and a better DP. Forage type has little impact on meat composition. Corn supplementation to grazing steers improves animal performance without having major impacts on meat composition. Literature Cited: Bhattacharya, A., J. Banu, M. Rahman, J. Causey, and G. Fernandes. 2006 Biological effects of conjugate linoleic acids in health and disease. J. Nutr. Biochem. 17(12): 789-810. Del Campo, M., G. Brito, J.M.S. de Lima, D.V. Martins, C. Sañudo, R.S. Julián, P. Hernández, and F. Montossi. 2008. Effects of feeding strategies including different proportion of pasture and concentrate, on carcass and meat quality traits in uruguayan steers. Meat Sci. 80(3): 753-760. Dierking, R.M., R.L. Kallenbach, and I.U. Grun. 2010. Effect of forage species on fatty acid content and performance of pasture-finished steers. Meat Sci. 85(4): 597-605. Duckett, S.K., Neel, J.P., Fontenot, J.P., and W.M. Clapham 2009. Effects of winter. stocker growth rate and finishing system on: III. tissue proximate, fatty acid, vitamin, and cholesterol content. J. Animal Science. 87(9): 2961-2970. Fincham, J.R., J.P. Fontenot, W.S. Swecker, J.H. Herbein, J.P. Neel, G. Scaglia, W.M. Clapham, and D.R. Notter 2009. Fatty acid metabolism and deposition in subcutaneous adipose tissue of pasture and feedlot-finished cattle. J. Anim. Sci. 87(10): 3259-3277. Franzluebbers, A.J. 2007. Integrated crop-livestock systems in the southeastern USA. Agron. J. 99(2): 361-372. French, P., C. Santon, F. Lawless, E.G. O'Riordan, F.J. Monahan, P.J. Caffrey, and A.P. Moloney. 2000. Fatty acid composition, including conjugated linoleic acid, of intramuscular fat from steers offered grazed grass, grass silage, or concentrate based diets. J. Anim. Sci. 78(11): 2849-2855. Golding, K.P., E.D. Wilson, P.D. Kemp, S.J. Pain, P.R. Kenyon, S.T. Morris, and P.G. Hutton. 2011. Mixed herb and legume pasture improves the growth of lambs post-weaning. Anim. Prod. Sci. 51(8): 717-723. Horn, G.W., P.A. Beck, J.G. Andrae, and S.I. Paisley. 2005. Designing supplements for stocker cattle grazing wheat pasture. J. Anim. Sci. 83(13)E69-E78. Kerth, C.R., K.W. Braden, R. Cox, L.K. Kerth, and D.L. Rankins Jr. 2007. Carcass, sensory, fat color, and consumer acceptance characteristics of Angus-cross steers finished on ryegrass (Lolim multiflorum) forage or on a high-concentrate diet. Meat Sci. 75:334-341. Latimori, N.J., A.M. Kloster, P.T. Garcia, F.J. Carduza, G. Grigioni, and N.A. Pensel. 2008.Diet and genotype effects on the quality index of beef produced in the Argentina Pampeana region. J. Meat Sci. 79(3): 463-469. Okuyama, H. 2001. High n-6 to n-3 ratio of dietary fatty acids rather than serum cholesterol as a major risk factor for coronary heart disease. Eur. J. Lipid Sci. 103: 418-422. Pavan, E., and S.K. Duckett. 2008. Corn oil or corn grain supplementation to steers Grazing endophyte-free tall fescue. I. effects on in vivo digestibility, performance, and carcass quality. J. Anim. Sci 86(11): 3215-3223. Roberts,  S.D.,  C.R.  Kerth,  K.W.  Braden,  D.L.  Rankins  Jr.,  L.  Kriese-­‐Anderson,  and  J.   W.   Prevatt.   2009.   Finishing   steers   on   winter   annual   ryegrass   (lolium  multiflorum   lam.)   with   varied   levels   of   corn   supplementation   I:   Effects   on   animal   performance,   carcass   traits,   and   forage   quality.   J.   Anim.   Sci.   87(8):  2690-­‐2699.     Russelle, M.P., H.M. Entz, A.J. Franzluebbers. 2007. Reconsidering integrated crop-livestock systems in North America. Agron. J. 99: 325-334. Table 1. Carcass Characteristics 1Kidney, Pelvic, Heartfat (KPH). 2USDA quality grade scale 3 = Low Select, 4 = High Select, 5 = Low Choice

Source: http://www.afgc.org/proceedings/2013/20.pdf