Abstract
Crossbred heifers (n = 64; animal was the experimental unit) were assigned to 1 of 8 treatments in a 4 × 2 factorial arrangement, with 4 treatment days-on-feed (DOF; 79, 100, 121, 142) and 2 levels of ractopamine hydrochloride (RAC) supplementation (0 or 300 mg × hd–1 × d–1). At 24 h postmortem, carcass traits were determined by trained personnel and longissimus samples were removed for muscle fiber type analyses. Boneless strip loins (IMPS #180) were fabricated and vacuum-packaged at 24 h postmortem and aged for 21 d, cut into 2.54 cm thick steaks, then frozen for no longer than 6 mo. After thawing for 24 h, Warner-Bratzler shear force (WBSF) and trained sensory panel analyses were conducted. Marbling was greater (P < 0.05) for control (CON; 0 mg x hd-1 x d-1 ractopamine hydrochloride) heifers than RAC heifers fed for either 79 or 100 d, but lower (P < 0.05) for CON heifers than RAC heifers fed for either 121 or 142 DOF. Feeding RAC had no effect (P > 0.05) on carcass traits, muscle fiber histology, or meat quality. The addition of RAC had no effect (P > 0.05) on Warner-Bratzler shear force. Feeding RAC had no negative impacts on carcass traits or meat quality and actually improved marbling scores in longer-fed heifers.
Highlights
IntroductionBeef lean appearance (i.e., color, shape, presentation) is a driving factor in beef retail acceptance, which influences both consumers and purveyors purchasing decisions (Carpenter et al, 2001)
Beef lean appearance is a driving factor in beef retail acceptance, which influences both consumers and purveyors purchasing decisions (Carpenter et al, 2001)
Previous research states that when beef pH exceeds 6.0 within 24 h after harvest meat quality can deteriorate, the eating experience is undesirable for the consumer, and economic losses begin to increase (Viljoen et al, 2002; Wulf et al, 2002; Pipek et al, 2003)
Summary
Beef lean appearance (i.e., color, shape, presentation) is a driving factor in beef retail acceptance, which influences both consumers and purveyors purchasing decisions (Carpenter et al, 2001). As it relates to the beef industry, dark, firm, and dry (DFD) lean otherwise known as “dark cutting” meat is characterized by an apparent dark purplish-red color, as a result of a pH great-. Past literature has shown that dark cutting beef has little to no acceptance among consumers and food service chefs when purchasing retail cuts from the rib or loin, compared to a normal beef carcass that exhibits a bright cherry-red colored lean with a pH ranging from 5.4 to 5.6 (Lawrie and Ledward, 2006; Aalhus et al, 2009). With a loss of over $36 per cwt according to current discounts (USDA-AMS, 2017), the estimated loss to the industry is $5.90/head per yr.
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