Dietary resin acids for better performance and intestinal immunomodulation – a study with broiler chickens

Results of a follow-up study, conducted Alimetrics Research Ltd in Finland, were presented at the 72nd annual meeting of the European Federation of Animal Science (EAAP2021) by Dr. Hannele Kettunen. The study was co-authored by S. Vartiainen, K. Vienola, J. Apajalahti and J. Vuorenmaa, and it was titled as “Immunomodulatory and performance-enhancing effects of dietary resin acids in broiler chickens”.

For the experiment, the hypothesis was that dietary resin acid concentrate (RAC) would affect the expression of genes related to collagen degradation  and inflammation in ileal epithelium. A protocol to study the effect of dietary a resin acid concentrate (RAC) on the growth performance of broiler chickens and on the expression of ten immune response -related genes in their intestine was designed.

On the first day of the experiment, male Ross 308 hatchlings were allocated into 20 pens, 14 chicks/pen. The two dietary treatments, both with ten replicates, included a wheat-soy -based control diet (CON) and the same diet amended with 175 g/ton of Resin acid concentrate with 40% resin acids (Hankkija Oy).

The birds were weighed on days 1, 21 and 35, and the feed intake and FCR were determined for the respective periods. Compared with the control treatments, RAC significantly increased bird weight on days 21 and 35, also improving FCR between days 1-21. Mortality was similar in all treatments.  

Two birds per pen were sampled on day 21 for gut mucosal tissue, and the samples were  analyzed by qPCR for the expression of ten inflammation-associated genes: nuclear factor (NF)-κB subunits 1 and 2, NF-κB inhibitor α, matrix metalloprotein (MMP)-2, MMP-7, MMP-9, interleukin (IL)-6, IL-10, tumor necrosis factor (TNF)-α and peroxisome proliferator activated receptor-ϒ.

The study did not show many significant effects for the ileal gene expression pattern: only the immune modulator NF-κB subunit 2 was affected (increased) by the dietary resin acids.

Thus, the study enforced the existing data suggesting improved performance of broiler chickens with dietary resin acid amendment. However, the data did not allow to draw strong conclusions on the effects of dietary resin acids and ileal gene expression on day 21. The study will be continued by a full-genome mRNA sequencing of the ileal samples.