Rapeseed supplements affect propitiously fatty acid composition of cow milk fat: A meta-analysis

Abstract Milk and dairy products together with animal fats are the major sources of undesirable saturated fatty acids (SFAs) in the human diet. Altering milk fat composition replacing a part of SFAs with unsaturated fatty acids thus offers an opportunity to decrease SFAs intake. Supplementation the diet of lactating cows with oilseeds has been a feasible method to improve milk fat composition. Rapeseed is the main source of lipids for animal nutrition in countries of temperate zone. Data from 22 studies published during 2010–2019, supplementing 20–292 g per kg diet DM (dry matter) daily of various rapeseed products (grouped into three categories, i) meal or expeller with fat content >5 g/100 g in DM, ii) intact or mechanically treated seeds and iii) oil), were assessed. Meta-analysis of the dataset (83 experimental variants, of these 30 and 53 control and supplemented, respectively) revealed significant improvement in fatty acid composition of milk fat. The supplementation of rapeseed products significantly decreased the proportion of SFAs (except for stearic acid) in favour particularly of oleic acid and thus of monounsaturated fatty acids. The contents of nutritionally required linoleic and α-linolenic acids were affected in a limited extent only. The efficacy of various forms of supplemented rapeseed on the main FAs and their groups differed. It can be therefore hardly given a univocal recommendation of an optimal form of rapeseed to be supplemented. Nevertheless, supplementation with meal/expeller seems to be applicable to farmers. The meta-analysis showed insignificant effects on milk yield and composition, except for fat content.