Do dietary condensed tannins affect the growth performance, fatty acid composition and lamb meat colour?

This meta-analysis evaluated the effect of condensed tannins (TC) (polyphenols formed from flavan-3-ol monomers) on the growth performance, fatty acid composition and lamb meat colour, based on the results of 41 publications (years 1998-2019) that allowed making up to 67 comparisons between batches of experimental lambs compared with a control lot within the same trial. These lots were divided into two groups, according to the dietary TC content difference between the control and experimental batch (medium level, 16 g/kg DM or high, 25 g/kg DM). The mean difference between each experimental group and its control lot was calculated for average daily gain, average feed intake, feed conversion rate, intramuscular fat, fatty acid profile and chromatic meat colour attributes. No significant differences were observed in the growth performance due to dietary TC inclusion, being much important the effect of other nutrients, such as crude protein and crude fat. A consistent reduction in the ratio of saturated fatty acids/polyunsaturated fatty acids and rumenic acid content in meat was observed. However, dietary inclusion of TC did not improve meat colour attributes compared to control groups.