The aim of the present work was to investigate the effects of feeding regimens (pasture vs. mixed diet) on meat quality, fatty acids, volatile compounds, and antioxidant properties in lamb meat. In total, 24 lambs were allotted into two feeding regimens at 10.23 kg live weight. Lambs were fed on pasture grass (PG group, n = 12) or mixed diet (M group, n = 12). Longissimus thoracis (LT) muscle samples from the M group had a higher intramuscular fat (IMF) (p < 0.05), pH45minvalue (p < 0.01), and ash (p < 0.05) than the PG group. In contrast, the shear force (p < 0.05), L*(p < 0.05), and b* (p < 0.001) in M group were lower than in PG group. Analyses indicated that PG group contained higher linolenic acid (C18:3n3) and docosatrienoic acid (C22:3n6) (p < 0.05) than the M group. Major volatile compounds in the muscles included hexanal, heptanal, nonanal, octanal, 1‐pentanol, 1‐hexanol, 1‐octen‐3‐ol, and 2,3‐octanedione. The levels of hexanal, nonanal, and 2,3‐octanedione were significantly lower in PG lamb muscle (p < 0.01). In contrast, 1‐pentanol and 1‐hexanol levels were higher in M lamb muscle (p < 0.01). Muscle from PG lamb exhibited higher catalase (CAT) and glutathione peroxidase (GPx) activity (p < 0.05). PG muscle also contained a higher radical‐scavenging ability (RSA; p < 0.001) and cupric‐reducing antioxidant capacity (CUPRAC; p < 0.05). Overall, the improved antioxidant status in PG muscle inhibited lipid peroxidation (aldehydes and ketones), thereby improving the meat quality.

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BACKGROUNDRumen bacteria play a critical role in feed degradation and productivity. This study evaluated the impact of feeding regimen on the rumen microbial populations and fatty acid composition of the meat of sheep. Twenty‐four Sunit sheep were raised on a grass pasture from birth to 9 months of age, at which time they were randomly divided into two feeding groups: pasture feeding (PF) and barn feeding (BF). Sheep in the PF group were allowed to graze freely on wild grassland for 3 months. Sheep in the BF group were confined for 3 months to a dry barn, in which they roamed freely with corn straw and corn.RESULTSSheep in the PF group had greater rumen bacteria diversity. The relative abundances of the genera Butyrivibrio_2, Saccharofermentans and Succiniclasticum were increased, and that of the genus RC9_gut_group was decreased, in the PF compared to the BF sheep. The n‐3 polyunsaturated fatty acid contents were greater in meat from PF sheep than from BF sheep. In addition, the α‐linolenic acid (C18:3 n‐3, ALA) and conjugated linoleic acid (CLA) contents were positively correlated with the abundance of Butyrivibrio_2.CONCLUSIONGrazing may improve the diversity of rumen bacteria and increase the proportion of ALA and CLA in sheep meat. © 2020 Society of Chemical Industry

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This study investigated the effects of probiotics on growth performance, meat quality, muscle fiber characteristics, volatile compounds, and antioxidant capacity in lambs. A total of 24 Sunit lambs were randomly allocated into two groups, each consisting of three replicates of four lambs. Throughout the experiment period, the lambs were fed with based diet (CON) and 10 g probiotics/d supplemented diet (PRO). Compared with the CON group, the number of lactic acid bacteria in fecal samples of PRO group was significantly increased ( p < .05) and the coliforms were significantly decreased ( p < .05). Dietary probiotics supplementation decreased pH 24h , L*, and shear force ( p < .05). The muscle fibers were switched from type IIB to type I, with a decrease in the mean cross‐sectional area (CSA) ( p < .05) of longissimus thoracis (LT) muscle. Also, probiotics altered the composition of meat volatile flavor compounds, such as nonanal, undecanal, 1‐pentanol, 1‐hexanol, and 2,3‐octanedione. In addition, probiotics increased the total antioxidative capacity (T‐AOC) and catalase (CAT) activity of LT muscle, while it decreased superoxide dismutase (SOD) activity ( p < .05). Overall, these results indicated that probiotics could be used as an effective feed additive by improving meat tenderness and flavor.