Kinetic activity index

metabolic

$$\frac{\sum \mathrm{PUFA}(\omega \text{-}3)}{\mathrm{C}\text{18:3}(\omega \text{-}3)}$$

Abbreviations

• KAI

Synonyms

• Activity index

Description

Represents the activity index (also referred to as the kinetic activity index, KAI), which is based on the indirect evaluation of $\beta$-oxidation activity in muscles to estimate energy expenditure. It is calculated as the ratio of total omega-3 polyunsaturated fatty acids ($\sum PUFA(\omega -3)$) to $\alpha$-linolenic acid (ALA, $C18:3(\omega -3)$).

This index is a metabolic indicator that describes the mobilization of n-3 long-chain PUFAs used for energy production (i.e., movement) and the resulting oxidative status. The ratio serves as an indicator of energy consumption ($\beta$-oxidation) and is typically higher in oxidative muscles than in glycolytic ones, reflecting higher kinetic activity in animals. Researchers use this index as an objective tool to measure the adaptability of a genetic line to extensive rearing systems (e.g., outdoor runs), because it accounts for the physical activity exerted during the animal’s life and can be used for ex post animal welfare assessment.

References

1. Failla et al., 2021
2. Dal Bosco et al., 2022
3. Kralik et al., 2025