Muscle quality traits and oxidative status of Iberian pigs supplemented with zinc and betaine under heat stress

The study analyzed the effect of supplemental zinc and betaine on meat quality and redox status of muscles (longissimus lumborum and gluteus medius) from heat- stressed pigs. Twenty-four pure Iberian pigs were assigned to one of three treatments (n = 8): control diet, Zn supplemented diet (120 mg/kg) and betaine supplemented diet (5 g/kg) that were all exposed to 30 °C during 28 days. No significant differences were observed in chemical composition and fatty acid profile of the muscles. The Zn diet improved the water retention capacity of longissimus, increased the antioxidant properties (ABTS and FRAP) and the glutathione peroxidase activity, and reduced the level of MDA. No significant effects associated to the betaine diet were observed in quality traits and antioxidant markers of muscles. These findings suggest that Zn supplementation may be used as a nutritional strategy to improve the antioxidant properties of meat of Iberian pigs subjected to heat stress conditions.

Effects of Dietary Zinc on Carcass Traits, Meat Quality, Antioxidant Status, and Tissue Zinc Accumulation of Pekin Ducks

This study investigated the effects of dietary zinc on carcass traits, meat quality, antioxidant capacity, and tissue zinc accumulation of Pekin ducks. A total of 768 1-day-old Pekin ducks were randomly allocated to six dietary treatments and penned in groups of 16 with 8 pens per treatment. Ducks were fed a basal corn-soybean meal diet supplemented with graded levels of zinc sulfate (0, 15, 30, 60, 120, 240 mg zinc/kg) for 35 days. The slaughter weight, carcass weight, eviscerated weight, and breast and leg muscle weight of Pekin ducks were increased with increasing dietary zinc levels (P < 0.05). Zinc supplementation increased the pH value at 24-h postmortem and the intramuscular fat (IMF) (P < 0.05), but decreased the lightness value, drip loss, and shear force in breast meat of ducks (P < 0.05). Increasing dietary zinc increased the activity of superoxide dismutase (SOD), glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), and the content of glutathione (GSH), as well as decreased the malondialdehyde (MDA) level in breast muscle (P < 0.05). RT-qPCR analysis demonstrated that supplemental zinc notably enhanced the transcription of SOD, GPX, GR, CAT, and nuclear factor erythroid 2-related factor 2 (Nrf2) (P < 0.05). Meanwhile, zinc accumulation in plasma, breast muscle, liver, and tibia were linearly increased with increasing zinc supplementation (P < 0.05). These results indicated that zinc supplementation could improve carcass traits and meat quality and increase the activities and mRNA levels of antioxidant enzymes in breast muscle of Pekin duck. Base on broken-line regression analysis that 91.32 mg/kg of dietary zinc was suggested for optimal carcass traits, meat quality, antioxidant capacity, and zinc deposition of Pekin duck.