Substituting ground woody plants for cottonseed hulls in lamb feedlot diets: carcass characteristics, adipose tissue fatty acid composition, and sensory panel traits

Abstract

Effects of using ground woody plants in Rambouillet wether lamb (n = 48) feedlot diets on carcass characteristics, adipose tissue fatty acid composition, and sensory panel traits were evaluated. In a randomized design study with two feeding periods (period 1 = fed a 70% concentrate diet from days 0 to 27; period 2 = fed an 86% concentrate diet from days 28 to 57), lambs were individually fed six diets that differed only by roughage source (n = 8 animals/treatment; initial BW = 32.9 ± 3.2 kg): cottonseed hulls (CSH; control) or ground wood consisting of either redberry (RED), blueberry (BLUE), one-seed (ONE), or eastern red cedar (ERC) Juniperus spp., or Prosopis glandulosa (MESQ). After 57 d, the lambs were humanely harvested and after chilling (2 ± 1 oC) 24 h, carcasses were evaluated for carcass traits. At 48 h postmortem, the longissimus thoracis (LT) was removed from the left side of the carcass, and after freezing for no more than 3 mo, were thawed for 24 h, cooked, and evaluated by a trained sensory panel. Additionally, volatile aroma chemicals on the LT were determined by gas chromatograph/mass spectrometer/olfactory (GC/MS/OF, respectively) analyses. Lamb HCW was greater (P = 0.01) for lambs fed CSH compared with all other diets, but lambs had similar (P > 0.08) LM area, back fat thickness, leg circumference, and body wall. Neither adipose tissue fatty acid composition (P > 0.08) nor trained sensory panel evaluation (P > 0.18) was affected by finishing diet roughage source. Of the 81 volatile aroma compounds found in the grilled lamb chops, only seven were affected (P < 0.05) by dietary roughage source and included 1-pentanol (a sweet, pleasant aroma), heptenal (a fishy aroma), pentanal (fermented, bready aroma description), 1-(1H-pyrol-2yl)-ethanone (caramel-like), 2-heptanone (cheesy, banana, fruity aromatic), 6,7-dodecanedione (unknown aroma), and butanoic acid (a sweaty, rancid aroma). The addition of any of four species of juniper or mesquite may be substituted for CSH without negatively affecting carcass fat and muscling, fatty acid, or sensory traits.

Effects of feeding juniper as a roughage on feedlot performance, carcass measurements, meat sensory attributes, and volatile aroma compounds of yearling Rambouillet wethers1,2

“…It is clear that the type and length of feeding period prior to harvest can determine lamb sensory characteristics. Sensory results from the present study agree with Kerth et al (2018) who reported that no differences in lamb loin chop-trained sensory panel scores were found when chops were taken from lambs finished on any of 4 different species of juniper. Whitney and Smith (2015) reported that substituting ground oat hay with juniper did not affect off-flavor, but enhanced juiciness, tenderness, and flavor intensity.…”

“…They attributed the greater sensory characteristics to the fact that ground juniper contains condensed tannins and terpenes (Stewart et al, 2015). Growth performance and sensory data in the current study are unique to previous investigations feeding juniper to sheep as yearlings (~18 mo at harvest) were utilized instead of lambs (~7 mo at harvest; Whitney et al, 2014;Whitney and Smith, 2015;Kerth et al, 2018). It is interesting to note, in the present study, that sensory scores in leg roasts were as much as 1.2, 7.4, and 2.1 units greater than loin chops for lamb ID, brown, and roasted sensory scores, respectively.…”

“…Whitney and Smith (2015) reported that substituting ground juniper for oat hay in lamb diets enhanced sensory panel traits and partially attributed the results to meat fatty acid composition and PSC in juniper. Kerth et al (2018) found that out of the 81 volatile aroma compounds identified in grilled loin chops, only 7 were affected by feeding 4 different species of juniper to lambs. Certainly, more information is needed to fully describe flavor components, especially of yearling mutton from animals fed alternative forages.…”

Review of Feeding Systems Affecting Production, Carcass Attributes, and Meat Quality of Ovine and Caprine Species

“…Yang et al [ 87 ] also showed that, compared with their stall-fed counterparts, pasture-grazed goat kids had superior flavor in regard to the longissimus muscle, which can be attributed to lower isoleucine and leucine contents. These outcomes could be because walking during pasture grazing promotes lipid oxidation in meat, increasing the synthesis of aldehyde and alcohol compounds [ 87 ] and resulting in different FA compositions of the meat [ 88 ]. In addition, compared with intensive feeding on concentrate diets, grazing pasture with concentrate supplementation exhibited a similar flavor effect on goat kids [ 53 ], possibly because of the similar meat IMF content between the two feeding systems [ 89 , 90 ].…”