Featured Hexagons Claims-01-01

Hotel Crowne Plaza Copenhagen Towers in Denmark hosted the ZeroZincSummit2022, which focused on discussing means to feed and manage piglets without the dietary inclusion of high doses of ZnO. The event was organized by the Danish Pig Research Centre SEGES and Danish Veterinary and Food Administration, and it attracted more than 450 delegates from the European and international swine industry members.

R&D Manager Hannele Kettunen from Hankkija FFI presented a summary of three studies proving that the resin acid -based Progres® is a highly suitable feed material for piglet feeds in ZnO-free feeding systems.

Resin acids (RAs) are antimicrobial and anti-inflammatory metabolites of coniferous trees. Dietary RAs reduce the inflammation-associated breakdown of collagen in the gut wall, thus supporting gut barrier functions. Piglet gut faces many challenges during weaning. Without specific dietary support, post-weaning diarrhoea (PWD) often occurs. We hypothesized that in-feed RAs improve the performance of sows and piglets, reduce PWD risk, and act as an immunomodulator in piglets. We conducted three studies to test the hypothesis (1-3).

Resin acids originate from coniferous trees

Materials, methods, and key results:

  • In Study 1, a total of 121 sows in 3 herds were randomized into 2 diet groups with RAs at 0 (Control) or 0.45 g/sow/day, one week before parturition. Sow and piglet performance, colostrum yield and concentrations of IgG and serum amyloid A (SAA) were measured, and sow fecal microbiota was analysed. In this study, RAs significantly increased colostrum yield, and IgG and SAA concentrations in colostrum. Dietary RAs also significantly increased the weight of piglets and improved the microbiota in sow feces.
Figure 1. In the 1st study, resin acids increased the levels of Immunoglobulin G and Serum Amyloid A in the colostrum
  • In Study 2, 40 sows were randomized into two diet groups with RAs at 0 or 135 g/ton 6 weeks before parturition and for the nursing period. From both groups, piglets were divided into pre-starter treatments with RAs at 0 or 90 g/ton. From all pre-starter groups, the piglets were further allocated at weaning (4 weeks) into dietary treatments with RAs at 0 or 90 g/ton, up to 7 weeks of age. Sow and piglet performance and fecal myeloperoxidase (MPO; a biomarker of intestinal inflammation) activity of weaned piglets were measured. The results showed that dietary RAs significantly increased the total number of piglets born and piglet weight at 7 weeks while reducing piglet mortality, PWD incidence, and fecal MPO. The best-performing piglets were those which were born to RA-fed sows and constantly fed with RAs.
Figure 2. Piglet weight at 7 wk was significantly improved by Progres®-amendment to the diet. C=Control, P=Resin acids=Progres®
  • Study 3 compared the effects of dietary RAs (90 g/ton), high dose of zinc (2500 g/ton) or control (non-supplemented) treatments in lipopolysaccharide (LPS)-challenged piglets. Blood serum was sampled at 1.5 and 3.0 hours after each challenge of intramuscular LPS-injection on days 7 and 21, and also on day 14 (between challenges). The serum samples were analysed for pro- and anti-inflammatory cytokines. In this study, performance was equal in all treatments. Compared with control, zinc and RAs increased serum levels of IL-6, IL-8, IL-10, and TNF-α post-LPS-challenge, but did not affect these cytokines between challenges. The levels of the anti-inflammatory cytokine interleukin-10 were highest in the RA-fed group.
Figure 3. The level of anti-inflammatory cytokine IL-10 was significantly increased by dietary resin acids, compared to other treatment, under 1.5 – 3 hours after and intramuscular LPS-injection (Days 7 and 21), but not when the challenge was not given (Day 14).

Discussion: Dietary RAs improved sow and piglet performance in two studies (1, 2). Reduced PWD incidence, compared to control, was seen in RA-group in Study 2. The increased colostrum yield, the concentration of IgG and SAA concentration in colostrum (1), and lower fecal MPO (2) suggest improved immune functions of piglets of RA-fed sows. It has been suggested that SAA in colostrum positively affects the gut development of neonate piglets. In Study 3, quite a similar modulation of cytokine profiles after LPS challenge by dietary RAs and a high dose of zinc suggest positive immunomodulation by dietary RAs in piglets. In conclusion, the results of these three studies support the hypothesis that dietary RA amendment improves sow and piglet performance, reduces the risk of PWD, and acts as a positive immunomodulator in piglets.


In these studies, dietary resin acids

  • Improved sow colostrum quality
  • Balanced the gut microbiota of sows and piglets
  • Improved piglet performance and reduced the PWD risk  
  • Acted as a positive immunomodulator in piglets

Overall, the results suggest that dietary resin acids can be a successful concept in piglet production without high dose of zinc.

Reference to the presentetaton:

H. Kettunen, S. Hasan, K. Uddin, C. Oliviero, F. Molist, X. Guan, R. Santos, J. Vuorenmaa. 2022. Dietary resin acids improved performance of sows and piglets and acted as an immune modulator for piglets. Abstract in: ZeroZincSummit2022. Copenhagen, Denmark, 22–23 June, 2022.

References to original articles:

  • Study 1. Hasan et al. (2018) Animal 13: 1599–1606
  • Study 2. Uddin et al. (2021) Animals 11:2511
  • Study 3. Guan et al. (2021) Front. Vet. Sci. 8:761742