Effect of dietary magnolia bark extract supplementation in finishing pigs on the oxidative stability of meat.

BACKGROUND: Magnolia bark extract (MBE) is a natural supplement with antioxidant, anti-inflammatory, and antimicrobial activities. Its properties suggest that the dietary supplementation in livestock could improve the quality of products. Therefore, the aim of this study was to investigate, for the first time, the effect of dietary MBE supplementation (0.33 mg/kg) in finishing pigs on the oxidative stability of meat. Oxidative stability is of paramount importance for pork, as it affects storage, retail, and consumer acceptance. For the purpose, the fatty acid profile, cholesterol, fat-soluble vitamins, antioxidant enzymes (catalase, glutathione peroxidase, and superoxide dismutase), non-enzymatic antioxidant capacity (TEAC, FRAP, and Folin-Ciocalteu assays), color stability, and lipid stability of pork were assessed. RESULTS: Concerning carcass characteristics, dietary MBE did not affect cold carcass yield, but reduced (P = 0.040) the chilling weight loss. The meat from pigs fed MBE had a lower (P = 0.031) lightness index than the control meat. No effect on intramuscular fat, cholesterol, and fatty acid profile was observed. Dietary MBE did not affect the content of vitamin E (α-tocopherol and γ-tocopherol) in pork, whereas it reduced (P = 0.021) the retinol content. The catalase activity was 18% higher (P = 0.008) in the meat from pigs fed MBE compared with the control group. The MBE supplementation reduced (P = 0.039) by 30% the thiobarbituric acid reactive substances (TBARS) in raw pork over 6 d of aerobic refrigerated storage. Instead, no effect on lipid oxidation was observed in cooked pork. Last, the meat from pigs fed MBE reduced Fe3+-ascorbate catalyzed lipid oxidation in muscle homogenates, with a lower (P = 0.034) TBARS value than the control group after 60 min of incubation. CONCLUSIONS: Dietary MBE supplementation in finishing pigs delayed the lipid oxidation in raw meat. This effect was combined with an increased catalase concentration. These results suggest that dietary MBE could have implications for improving the shelf-life of pork.

Effect of different levels of organic zinc supplementation on pork quality.

This study investigated the effect of two supplementation levels of zinc glycinate (ZnGly) on performance, carcass characteristics, and meat quality of growing-finishing pigs. Thirty pigs (bodyweight: 61 ± 4.0 kg) were assigned to three treatments and fed ad libitum for 56 days a diet supplemented with 0 (control), 45 (Zn45), or 100 mg/kg (Zn100) of ZnGly. The highest ZnGly supplementation lowered the average daily gain (P = 0.031); while, cold carcass weight did not differ between treatments. Both ZnGly levels reduced carcass chill loss (P < 0.001). Micromineral content, color stability, and fatty acid profile of meat were not altered by ZnGly. Superoxide dismutase activity was lowered by Zn45 compared to control (P = 0.007); while, catalase activity was enhanced by Zn100 (P = 0.003). Although ZnGly supplementation did not influence lipid oxidation in raw meat and in meat homogenates incubated with pro-oxidant catalysts, Zn45 limited lipid oxidation in cooked meat (P = 0.037). Our results demonstrated that supplementing pigs with 45 mg/kg of ZnGly could improve the oxidative stability of pork subjected to strong pro-oxidant conditions, but this effect needs to be further elucidated.

Dietary Supplementation of Tannin-Extracts to Lambs: Effects on Meat Fatty Acids Composition and Stability and on Microbial Characteristics.

Two extracts derived from plant material rich in hydrolysable (Tara, T; Caesalpinia spinosa) or condensed (Mimosa, M; Acacia mearnsii) tannins were added to lamb's diet and their effects on meat quality and on microbial population were evaluated; a diet without tannins represented the Control (C). Meat pH, vitamin E, intramuscular fat content and muscle fatty acid composition were determined. Oxidative stability and microbiological analyses were performed on meat samples after 0, 4 and 7 days of refrigerated storage. Psychrotrophic bacteria were identified through MALDI-TOF MS analysis. Regarding meat fatty acids, Tara treatment decreased the percentage of monounsaturated fatty acids. The counts of all microbial groups were similar among dietary treatments at day 0, while a significant reduction of microbial loads was observed in T-group at day 7. Pseudomonas fluorescens group count was significantly affected by T extract supplementation. The MALDI-TOF MS identification revealed the dominance of Pseudomonas fragi species in all samples while Pseudomonas lundensis, Brochothrix thermosphacta and Candida famata were revealed only in control ones. In conclusions, the tannin extract supplementation is a promising dietary strategy to preserve lamb meat quality.

Dried tomato pomace supplementation to reduce lamb concentrate intake: Effects on growth performance and meat quality.

The effect of dried tomato pomace (DTP) was tested on lamb performances, meat fatty acids and oxidative stability. For 36 days, one group of lambs (n = 7; CON) was fed a commercial concentrate, while the other group (n = 7; DTP) received DTP in addition to CON diet. The administration of DTP reduced (P < .05) concentrate intake, with no effect on animal performances. The DTP treatment tended to increase total polyunsaturated fatty acids (PUFA; P = .075), PUFA n-6 (P = .071), α-linolenic acid (P = .096) and increased linoleic acid (P < .05), γ-tocopherol (P < .001) and retinol (P < .001) in meat. In raw meat, DTP treatment increased L* (P = .059), b* (P < .05), C* (P = .052) and H* (P < .05) values compared to CON, while lipid oxidation was not affected. In meat homogenates incubated with pro-oxidants, DTP tended to reduce 2-thiobarbituric acid reactive substances (TBARS; P = .088). Therefore, DTP supplementation decreased the consumption of commercial concentrate without detrimental effects on animal performances and meat quality traits.

Dietary quebracho tannins are not absorbed, but increase the antioxidant capacity of liver and plasma in sheep.

A total of sixteen lambs were divided into two groups and fed two different diets. Of these, eight lambs were fed a control diet (C) and eight lambs were fed the C diet supplemented with quebracho tannins (C+T). The objective of the present study was to assess whether dietary quebracho tannins can improve the antioxidant capacity of lamb liver and plasma and if such improvement is due to a direct transfer of phenolic compounds or their metabolites, to the animal tissues. Feed, liver and plasma samples were purified by solid-phase extraction (SPE) and analysed by liquid chromatography-MS for phenolic compounds. Profisitinidin compounds were identified in the C+T diet. However, no phenolic compounds were found in lamb tissues. The liver and the plasma from lambs fed the C+T diet displayed a greater antioxidant capacity than tissues from lambs fed the C diet, but only when samples were not purified with SPE. Profisetinidin tannins from quebracho seem not to be degraded or absorbed in the gastrointestinal tract. However, they induced antioxidant effects in animal tissues.

Bacterial and protozoal communities and fatty acid profile in the rumen of sheep fed a diet containing added tannins.

This study evaluated the effects of tannins on ruminal biohydrogenation (BH) due to shifts in the ruminal microbial environment in sheep. Thirteen lambs (45 days of age) were assigned to two dietary treatments: seven lambs were fed a barley-based concentrate (control group) while the other six lambs received the same concentrate with supplemental quebracho tannins (9.57% of dry matter). At 122 days of age, the lambs were slaughtered, and the ruminal contents were subjected to fatty acid analysis and sampled to quantify populations of Butyrivibrio fibrisolvens, which converts C(18:2) c9-c12 (linoleic acid [LA]) to C(18:2) c9-t11 (rumenic acid [RA]) and then RA to C(18:1) t11 (vaccenic acid [VA]); we also sampled for Butyrivibrio proteoclasticus, which converts VA to C(18:0) (stearic acid [SA]). Tannins increased (P < 0.005) VA in the rumen compared to the tannin-free diet. The concentration of SA was not affected by tannins. The SA/VA ratio was lower (P < 0.005) for the tannin-fed lambs than for the controls, suggesting that the last step of the BH process was inhibited by tannins. The B. proteoclasticus population was lower (-30.6%; P < 0.1), and B. fibrisolvens and protozoan populations were higher (+107% and +56.1%, respectively; P < 0.05) in the rumen of lambs fed the tannin-supplemented diet than in controls. These results suggest that quebracho tannins altered BH by changing ruminal microbial populations.