# Effects of a Dietary Blend of Essential Oils, Capsaicin, and Yeast Metabolites on Performance, Physiological, Metabolism, and Immune Response of Heat-Stressed Pigs

## TL;DR

This study tested a natural feed additive on heat-stressed pigs and found it may reduce fat deposition without improving overall performance.

## Contribution

The study evaluates a specific blend of essential oils, capsaicin, and yeast metabolites in mitigating heat stress effects in pigs.

## Key findings

- The additive did not improve overall performance or immune response in heat-stressed pigs.
- Pigs fed the blend showed a tendency to reduce fat deposition compared to the control group.
- The additive increased creatinine levels and showed a tendency to elevate LDH in blood markers.

## Abstract

High environmental temperatures can negatively impact pig health, growth, and metabolism. Heat-stressed pigs often reduce their feed intake and experience impaired nutrient absorption, increased fat deposition, and inflammation, all of which compromise growth performance. Natural feed additives, such as compounds derived from essential oils, yeast metabolites, and capsaicin (a compound from chili peppers), have shown potential to support gut health, modulate immune responses, and improve animal performance under stressful conditions. This study investigated the effects of a dietary blend containing essential oils, capsaicin, and yeast metabolites on pigs raised under chronic heat stress. Pigs were monitored for growth, body composition, blood markers, and metabolism over 56 days at a constant high temperature (35 °C). While the additive did not improve overall performance, pigs fed the blend tended to have reduced fat deposition and showed changes in some biochemical indicators related to metabolism. These findings suggest that although this specific blend did not fully mitigate the effects of heat stress, it may influence fat metabolism and deserves further investigation. Understanding how natural additives affect pigs under heat stress can help develop nutritional strategies to support animal health and productivity in increasingly warm climates.

This study investigated the effects of a dietary additive composed of compounds derived from essential oils (carvacrol, eugenol, cinnamaldehyde), capsaicin, and yeast metabolites on the performance, body composition, metabolism, and immune status of pigs under chronic heat stress (HS). A total of 24 crossbred gilts (50 ± 3.98 kg) were assigned to one of two diets: a control diet (CON) or the same diet supplemented with the additive blend (2.5 g/kg; BLEND). Animals were housed collectively, with individual feed intake recorded using automatic precision feeders over a 56-day period at a constant ambient temperature of 35 °C. Heat stress increased rectal temperature initially (p < 0.01), which gradually declined over time. No significant differences were found in overall performance or tissue deposition between treatments (p > 0.05), though pigs fed the BLEND diet tended to have an 18% lower fat deposition compared with the CON group (148.3 vs. 121.3 g/d, p = 0.094). The additive had no effect on inflammatory or most biochemical parameters, except for increased creatinine compared with the CON group (1.76 vs. 1.63 mg/dL; p = 0.032) and a tendency for elevated LDH (1064.87 vs. 939.17 U/L; p = 0.075). In conclusion, chronic HS impaired metabolic and immune parameters and altered body composition. The dietary blend did not enhance performance but showed a tendency to reduce lipid deposition under thermal stress conditions. Further studies are needed to elucidate the individual and combined actions of this feed additive in mitigating the impacts of HS on pigs.