Effects of feeding cattle calcium hydroxide treated corn stover during backgrounding on carcass characteristics and beef quality

Abstract

Sixty-seven purebred Angus steers (initial mean BW 197 kg.) were used to evaluate the effects of calcium hydroxide treated corn stover in backgrounding diets and a common finishing phase. Steers were randomly assigned to 1 of 4 dietary treatments: untreated corn stover (CON), corn stover treated with 50% DM water (H2O); 50% DM, water and calcium hydroxide treated corn stover (Ca(OH)2); grazing on a turnip cover crop (CC) for 29 days before adapted to ad libitum alfalfa haylage diet fed in feed bunks for remaining 20 d of backgrounding. Steers were fed individually using a Calan system for 49 days. All diets were formulated on a dry matter (DM) basis to contain 30% corn stover, 15% alfalfa haylage, 25% dried distillers grains with solubles, 25% dry rolled corn, and 5% supplement containing monensin. Upon completion of dietary treatments, steers were fed a common feedlot diet for 240 days. Steers were then harvested at a commercial abattoir, and carcass characteristics were recorded 48 hours postmortem. Strip loins and shoulder clods (IMPS #180 and #114) from the right side of the carcass were collected. All primals were transported to the University of Minnesota Meat Laboratory for further evaluation. Strip loins were fabricated into 2.54 cm steaks at 96 hours postmortem. Strip loin steaks were used to evaluate vacuum purge, cook loss, and Warner-Bratzler shear force (WBSF), color scores, as well as consumer acceptability. Shoulder clods were processed to ground beef for evaluation of subjective and objective color scores as well as Thiobarbituric Acid Reactive Substances (TBARS). Portions of ground beef were then processed into bologna to be evaluated for objective and subjective color as well as consumer acceptability. Dietary treatment had no effect on carcass characteristics including hot carcass weight (HCW) (P = 0.694), ribeye area (REA) (P = 0.259), 12th rib backfat (P = 0.780), marbling score (P = 0.845), USDA Yield Grade (P = 0.890), and USDA Quality Grade (P = 0.877). Although purge loss (P = 0.884) and cook loss (P = 0.149) were not affected by treatment, WBSF values were lower for CC than CON (1.6 v 2.23kg respectively; P = 0.001). Lean color scores for fresh steaks were affected by dietary treatment (P = .004). On day 5, CC (5.34) was less bright cherry red than CON (5.66; P = .017) and H2O (5.76; P = .001). On day 7, CC (4.92) was less bright cherry red than CON (5.22; P = .032) and H2O (5.29; P = .007). Overall desirability scores for fresh steaks differed (P = .011) among dietary treatments with H2O being more desirable than CC on day 5 (5.35 v 4.93; P = .023) and Ca(OH)2 was more desirable than CC on day 6 (5.36 v 4.98; P = .047). Discoloration scores for fresh steaks varied among treatments (P = .003). On day 5, CC (10.02) was more discolored than H2O (10.30; P = .019) and Ca(OH)2 (10.32; P = .016). On day 6, steaks from CC were more discolored than H2O steaks (9.27 v 9.57; P = .013). Day 7 fresh steak discoloration scores shows that CC (9.13) was more discolored than CON (9.42; P = .027), H2O (9.5; P = .003), and Ca(OH)2 (9.42; P = .024). Yellowness (b*) color values for ground beef varied among treatments (P = .025). Ground beef lean color as assed by a trained panel was affected by dietary treatment (P < .001). On day 0, H2O (6.77) was less bright cherry red than CON (7.06; P = .022) and Ca(OH)2 (7.13 P = .006). On day 1, CON (6.91) was more bright cherry red than H2O (6.51; P = .012) and CC (6.52; P = .017). On day 2, CON (6.12) was more bright cherry red than H2O (5.7; P = .006) and CC (5.7; P = .007). On day 3, CON (5.32) was brighter than CC (4.72; P < .001) and Ca(OH)2 (4.98; P = .029), and H2O was brighter than CC (5.1 v 4.72; P = .005). On day 4, CC (3.47) was less bright red than H2O (3.90; P < .001) and CON (3.84; P = .006). Desirability scores were affected by dietary treatment (P < .001). On Day 0, H2O (7.16) ground beef samples were less desirable than CON (7.39; P = .032) and Ca(OH)2 (7.44; P = .016). On day 1, CON (7.21 was more desirable than H2O (6.74; P = .005) and CC (6.77; P = .009). On day 2, CON (6.32) was more desirable than H2O (5.80; P < .001) and CC (5.68; P < .001), and CC was less desirable than Ca(OH)2 (5.68 v 6.04; P = .031). On day 3, CON (5.36) was more desirable than H2O (4.93; P = .004), CC (4.54; P < .001) and Ca(OH)2 (4.71; P < .001); H2O was more desirable than CC (4.93 vs 4.54; P = .006). On day 4, CC (3.00) was less desirable than CON (3.46; P = .001) and H2O (3.44; P = .016). On day 5, Ca(OH)2 (2.14) was less desirable than CON (2.44; P = .039) and H2O (2.43; P = .016). Discoloration scores for ground beef was affected by dietary treatment (P < .001). On day 2, H2O was more discolored than Ca(OH)2 (8.55 v 9.29; P = .039). On day 3, CON (8.83) was less discolored than H2O (8.09; P = .028), CC (7.39; P < .001) and Ca(OH)2 (7.59; P < .001); H2O was less discolored than CC (8.09 v 7.39; P = .028). On day 4, H2O was less discolored than CC (6.3 v 5.68; P = .034). In regards to steak sensory, no differences were found in flavor liking (P = 0.102), juiciness (P = 0.375), or off-flavor (P = 0.313). Differences were found in overall liking (P = 0.008) with CC being more liked than CON (P = 0.013) and Ca(OH)2 (P = 0.019). Texture liking was affected by dietary treatment (P < 0.001), with CC higher than CON (P < 0.001), H2O (P = 0.021), and Ca(OH)2 (P < 0.001). Toughness scores were also affected by dietary treatment (P < 0.001) with CC having the lowest values compared to CON (P < 0.001), H2O (P = 0.015), and Ca(OH)2 (P < 0.001). For bologna sensory, no differences among dietary treatments were found for overall liking (P = 0.610), flavor liking (P = 0.707), texture liking (P = 0.828), juiciness (P = 0.371), and off-flavor (P = 0.716). A difference in toughness was found (P = 0.011) with H2O being more tough than Ca(OH)2 (P = 0.008). It was concluded that the use of calcium hydroxide treatment of corn stover in backgrounding diets of beef calves does not affect carcass characteristics or moisture loss, but does affect fresh and further processed beef characteristics. Although there were differences found among dietary treatments for meat characteristics, these differences do not appear to be large enough from a practical stand point to make a recommendation against the feeding of alkali-treated corn stover during calf backgrounding.