By Zhong-Xing Rao, Mike Tokach, Jason Woodworth, Joel DeRouchey, Robert Goodband, Jordan Gebhardt and Katelyn Gaffield, Kansas State University

During stressful periods, such as weaning, the need for antioxidants increases. Antioxidants neutralize free radicals by electron donation, complex formation between oxidizing elements, or the regeneration of other antioxidants. Besides endogenous enzymatic antioxidants [e. g., superoxide dismutase, catalase, glutathione peroxidase], natural non-enzymatic antioxidants (e. g., vitamins E and C, carotenoids, polyphenols) are also involved in protecting the cells from free radicals.

The natural polyphenol-based product, Cabanin CSD, contains selected extracts from grapes, citrus, blackcurrant and chestnuts, all with high concentrations of polyphenols that can provide high antioxidative activity. Previous European university trials observed that Cabanin CSD improved growth performance and reduced feed costs when partly replacing vitamin E. Polyphenols have also shown positive effects on immune system.

We hypothesized that Cabanin CSD could potentially be used as an effective antioxidant replacer in diets where the minimum NRC (2012) vitamin E requirement was being met. Therefore, the objectives of this experiment were to evaluate the effects of vitamin E equivalence levels (15, 75 and 575 IU/kg), and vitamin E replacement strategies of replacing 60 IU/kg of vitamin E with Cabanin CSD in diets above the minimum vitamin E requirement on growth performance, antioxidant status (TBARS and SOD), complete blood count, and cytokine panels of nursery pigs from weaning to 42 d post-weaning.

Animals, diets and procedures

A total of 300 pigs (241 × 600; DNA, Columbus, Nebraska; initially 13.1 lb and 21 d of age) were placed in pens of five pigs each based on initial BW and gender. Pens of pigs were randomly allotted to the five treatments in a completely randomized design with 12 replicate pens per treatment. Treatment diets were fed in three phases (phase 1: d 0 to 10; phase 2: d 10 to 21; and phase 3: d 21 to 42) in meal form. The vitamin E form (20,000 IU/lb, DSM, Parsippany, New Jersey) used in this trial was DL-α-tocopherol acetate with 1 mg providing 1 IU of vitamin E equivalence. The natural polyphenol-based product (Cabanin CSD, R2 Argo, Denmark contained selected extracts from grapes, citrus, blackcurrant and chestnuts. These ingredients contained high concentrations of polyphenols in the form of phenolic acids, flavonoids and tannins, which have shown great antioxidative activity.

The Cabanin CSD was assumed to have a 50% equivalency to vitamin E (DL-α-tocopherol acetate) based on a previous university trial conducted at Freie Universität Berlin (Germany) for weaned pigs. Thus, 1 mg of Cabanin CSD provided 0.5 IU of vitamin E equivalence. The total polyphenol content was 9.2 % for this specific lot of Cabanin CSD product used in this trial.

A control treatment was formulated to provide 15 IU/kg of vitamin E equivalence from vitamin E to meet the requirement estimate for vitamin E. This control diet with 15 IU/kg of vitamin E was then used as the basal diet for three replacement strategy diets (Table 1). First, an additional 60 IU/kg of vitamin E was added for a total of 75 IU/kg of vitamin E equivalence. Second, 50% of the additional vitamin E (30 IU/kg) was replaced with the vitamin E equivalence from Cabanin CSD. Third, all 60 IU/kg of supplemental vitamin E was replaced with the equivalency of Cabanin CSD. These three replacement strategies allowed us to determine the effects of replacing vitamin E with Cabanin CSD at different ratios for the additional 60 IU/kg of vitamin E equivalence added to diets containing a minimum vitamin E requirement estimate (15 IU/kg). The fifth treatment was formulated to provide a total of 575 IU/kg of vitamin E equivalence with 75 IU/kg from vitamin E and 500 IU/kg from Cabanin CSD to evaluate whether there are negative effects of feeding nursery pigs a high level of Cabanin CSD.

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Pen weights and feed disappearance were measured on d 0, 10, 21, 31, 38 and 42 to determine average daily gain, average daily feed intake and feed: gain. The pigs were healthy as there were few medical treatments and no mortality throughout the 42-d trial. Whole blood and serum samples were collected from one median-weight pig of each pen on d 10 and 42 of the experiment for CBC, serum cytokine panel, serum SOD, and serum thiobarbituric acid reactive substances (TBARS).

Results

Growth performance
There was no evidence of differences (P > 0.10) in ADG and ADFI as vitamin E equivalence increased or between replacement strategies throughout the entire 42-d experimental period (Table 2). There was a tendency of improvement in F/G as vitamin E equivalence increased in overall (d 0 to 42) F/G (linear, P = 0.075).

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Antioxidant status (TBARS and SOD)

For serum TBARS, there was no evidence of vitamin E equivalence × day interaction, treatment × day interaction, vitamin E equivalence effect, treatment effect, or day effect (P > 0.10). However, there was a vitamin E equivalence × day interaction (P = 0.050) on serum SOD activity (Figure 1). Increasing vitamin E equivalence increased (linear, P = 0.036) serum SOD activity on d 42 but not on d 10 (linear, P = 0.616). Moreover, there was no treatment effect, day effect, or treatment × day interaction (P > 0.10) in serum SOD activity between the five dietary treatments on d 10 and 42.

KSU. Figure 1. Serum SOD activity on d 10 and 42. Total E equivalence is the combination of vitamin E equivalence provided by vitamin E and Cabanin CSD (R2 Argo, Denmark). Increasing total vitamin E equivalence increased SOD on d 42 (linear, P = 0.036) but not on d 10 (linear, P = 0.616) with no difference between methods of increasing total E equivalence.

Complete blood count and cytokines

There was no evidence (P > 0.10) of vitamin E equivalence × day interaction and treatment × day interaction for all CBC criteria or serum cytokine levels. Increasing vitamin E equivalence tended to increase (quadratic, P = 0.070) leukocyte concentration and increased (quadratic, P = 0.045) eosinophil concentration from 15 to 75 IU/kg of vitamin E equivalence then reduced at 575 IU/kg.

In summary, increasing vitamin E equivalence by the addition of vitamin E or Cabanin CSD improve feed efficiency, which may be related to the improved serum SOD activity. Moreover, we found no evidence of difference between the three vitamin E replacement strategies in all response criteria. Thus, this suggests that Cabanin CSD can be used as an effective replacement for the 60 IU/kg of additional vitamin E added to diets that met the basal vitamin E requirement (15 IU/kg) for nursery pigs.