Quantitative relationships between ingested and intestinal flows of linoleic and alpha-linolenic acids, body weight and milk performance in mid-lactation dairy cows.

Linoleic acid (LA) and alpha-linolenic acid (ALA) are essential fatty acids found in variable quantities in ruminant feedstuffs. Revision of French feed unit systems in 2018 has proposed the reassessment of energy requirements through a between-experiment approach expressing metabolisable energy supply as a function of the energy expenditures for maintenance and production, with these expenditures that reflect homeorhetic regulations. Based on the same approach, LA and ALA intake can be related to animal characteristics (i.e., BW) reflecting maintenance expenditures and secretion characteristics (i.e., milk yield, milk fat content and contents of LA and ALA in milk fat). Therefore, the objective of this work was to analyse the between-experiment relationships between ingested, duodenal, or absorbed flows of LA and ALA, BW and milk LA and ALA secretion by meta-analysis in mid-lactation dairy cows. These relationships were analysed using LA and ALA subsets of 96 and 99 experiments, respectively. Between-experiment regressions of...