The transition – also called periparturient – period predisposes dairy cows to metabolic stress and low-grade inflammation which increases the risk of health problems and reduced production capacity. Most of the health problems of cows originate from the transition period. Solutions for relieving the transition stress would be valuable, as they would result in a faster onset of milk production, a higher peak in milk quantity, and a better overall milk yield.

In experiments with broiler chickens, diet-derived coniferous resin acids reduced inflammation-associated breakdown of the structural proteins in the gut. Similar research has not been conducted in dairy cows or other ruminants. However, it is possible that dietary resin acids could support gastrointestinal functions also in ruminants, and help the transition cow to cope with the metabolic stress involved with calving and onset of milk production.

To study the effect of resin acids on periparturient cows, Hankkija conducted a trial at Natural Resources Institute Finland (Luke). Nordic Red Cows, 36 in total, were divided into three dietary treatments: “Control” with unamended feed, “Progres” with 7g of tall oil fatty acid (TOFA)-based Progres® Liquid/cow/day, and “RAC” with 1.7 g Resin Acid Concentrate/cow/day.  Both Progres and RAC dosing resulted in 0.63 g resin acids/cow/day. For each cow, the trial started three weeks before calving and continued for 10 weeks after calving.

The cows were sampled for rumen microbiota, blood, colostrum and milk, and feces, and the samples were analysed for a variety of parameters. The results of this experiment have now been published in the peer-reviewed scientific journal Livestock Science. 

Although the dietary treatments showed similar milk yield over the 10-week period, both resin acid treatments increased the peak of milk production during weeks 2 and 3 after calving (Figure 1). At that time, RAC-group produced on average 2.1 kg/day more milk than the Control group (P < 0.075). This interesting result suggests that dietary resin acids may indeed have positive effects to onset of lactation. More research with a higher number of animals is needed to study this phenomenon.

Fig. 1. Yield of Energy Corrected Milk (ECM) per cow per day

Another highly interesting finding of the study was that cows on resin acid diets had less infections and any other types of sickness than control cows (Figure 2) and also the number of cow-days with sickness or infection were reduced by RAC (Figure 3). Of these results, only the number and cow-days with infection were included in the publication. These results give strong support to the concept that dietary resin acids reduce inflammatory processes and support the physiology of periparturient cows. Further research is needed to reveal the mechanism-of-action behind these phenomena.

Although coniferous resin acids have antimicrobial properties, in the present study the rumen microbiota was not markedly affected by either of the resin acid -treatments. Resin acids were not found in milk samples, but they were present in the feces. This suggests that resin acids are able to bypass rumen at least partly, and may therefore have effects on intestinal epithelium. The blood samples were analysed for a biomarker of intestinal permeability: intestinal fatty acid binding protein (I-FABP). A slight reduction of I-FABP was observed in the RAC-treatment (P = 0.09) possibly suggesting towards improved gut barrier functions in that treatment (Figure 4).

The study also revealed that Progres has positive immunomodulatory effects, as suggested e.g. by the increased serum quantity of the anti-inflammatory cytokine IL-10 in the Progres treatment. The results of the experiment suggest at least partly different mechanism-of-action for the TOFA-based Progres Liquid and the resin acid concentrate RAC. Further studies are needed to reveal whether the differences are based on resin acid bioavailability from these matrices, or whether other factors are involved.

Fig 4. Biomarker of intestinal permeability I-FABP in the serum samples
Fig 5. The anti-inflammatory cytokine IL-10 in the serum samples

Reference: Kairenius, P., Qin, N., Tapio, I., Mäntysaari, P., Franco, M., Lidauer, P., Stefański, T., Lidauer, M.H., Junnikkala, S., Niku, M., Kettunen, H. and Rinne, M. (2021) The effects of dietary resin acid inclusion on productive, physiological and rumen microbiome responses of dairy cows during early lactation. Livestock Science 255: 104798.