SUMMARY
  • Transportation stress can affect carcass quality and also the metabolism and immune function of pigs.
  • Feed additives with antioxidant function, such as vitamin E and oregano essential oil can help to alleviate stress associated with transportation prior to slaughter.
  • In this study (Zhang et al., 2016) Orego-Stim helped reduce transport stress in pigs whilst providing antioxidant activity similar to vitamin E, and thus could contribute towards improved meat quality whilst saving on feed costs.
BACKGROUND
  • Increased stress prior to slaughter as a result of transportation can impact meat quality, resulting in an increased drip loss and incidence of pale, soft and exudative (PSE) meat, raise welfare concerns and cause an economic impact.
  • USA field trials between 2000 and 2007 reported that of all pigs marketed, 0.25% died during transport. In Germany this figure was reported to be 0.2% (Schutte, 1994). It is estimated that in the USA alone, the number of pigs dead on arrival following transportation for slaughter costs pork producers more than $3 million per annum (Faucitano, 2013).
  • Lipid peroxidation is an indicator of oxidative stress and can be assessed based on levels of malondialdehyde (MDA). MDA is a terminal product of lipid peroxidation, therefore an increased MDA concentration indicates an increased extent of oxidative stress. Additionally, increased levels of reactive oxygen species (ROS), which are produced during oxidation, also heighten the animal’s risk to oxidative stress.
  • Serum concentrations of hormones, such as such as cortisol and norepinephrine, are hallmark indicators of stress in livestock.
  • Oregano essential oil has well-documented antioxidant properties. Orego-Stim is a high quality eubiotic containing 100% natural oregano essential oil.

 

TRIAL DESIGN

An independent study was conducted at Huazhong Agricultural University, China, to assess the effect of Orego-Stim on alleviating stress and increasing antioxidant function after the transportation of finishing pigs. 180 crossbred finishing pigs (Landrace x Yorkshire) were randomly allocated to 1 of 3 dietary groups; a basal diet (Control), a vitamin E supplemented diet (200 mg/kg feed) (positive control) or a diet supplemented with Orego-Stim at 500 g/tonne of feed (OS). Pigs were provided with ad libitum access to feed and water, and all basal diets were formulated to meet or exceed nutrient requirements for growing-finishing swine (The National Research Council, 2012) and included 60iu/kg vitamin E. Diets were fed for 28 days, following which each group was split into two subgroups and subjected to either no transportation stress or transportation stress. Blood and liver samples were collected immediately after slaughter from 12 pigs from each dietary group within each transport subgroup (total of 72 pigs), to enable analysis of serum cortisol and norepinephrine concentrations and analysis of both liver and serum ROS and MDA concentrations.

RESULTS

Figure 1. Serum cortisol (ng/ml) (A) and norepinephrine (ng/ml) (B) concentrations in pigs from different dietary groups subject to no stress or stress during transport. (Adapted from (Zhang et al., 2016)). Differing lowercase letters indicate significant difference (p<0.05).

Figure 2. Serum ROS (IU/mol) (A) and MDA (nmol/ml) (B) concentrations in pigs from different dietary groups subject to no stress or stress during transport. (Adapted from (Zhang et al., 2016)).

Figure 3. Liver ROS (IU/mol) (A) and MDA (nmol/mg protein) (B) concentrations in pigs from different dietary groups subject to no stress or stress during transport. (Adapted from (Zhang et al., 2016)).

  • Dietary supplementation with both vitamin E and Orego-Stim significantly reduced (p=0.01) serum stress-response hormone cortisol concentrations compared with the control diet in both transport groups, however only Orego-Stim significantly reduced norepinephrine concentrations in pigs subject to transport stress (p<0.05) (Figure 1).
  • Orego-Stim supplementation tended to reduce serum ROS and MDA concentrations more than vitamin E in pigs from both no stress and transportation stress groups (Figure 2).
  • Liver ROS concentrations were significantly higher in pigs subject to stress as opposed to no stress during transport (p<0.01). Supplementation with Orego-Stim tended to reduce liver ROS concentrations in both transport groups. Liver MDA concentrations were also higher in pigs subject to transport stress (p=0.02) and were significantly reduced in both transport groups following Orego-Stim and vitamin E supplementation (p<0.01) (Figure 3).
  • Results of the trial demonstrate that Orego-Stim is effective in mitigating transport stress by potentially enhancing anti-oxidative function and subsequent meat quality, with results similar to, or better than, those seen with vitamin E supplementation, in addition to meeting animal requirements according to NRC (2012).

 

 

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