Nutrient digetibility and production responses of lactating dairy cows when saturated free fatty acid supplements are included in diets: A meta-analysis

Our objective was to perform a series of meta-analyses evaluate the effects diets supplemented with saturated free fatty acid (FA) supplements (SFAA) compared nonfat control (CON) on nutrient digestibility and production responses lactating dairy cows determine whether experimental design affects SFFA. We divided SFFA into C16:0-enriched (PALM, FA ≥80% C16:0) C16:0+C18:0-enriched (MIX, C16:0+C18:0). The database formed from 32 peer-reviewed publications at ≤3% diet dry matter (DM). completed 3 different meet our objectives. analyzed interaction between (continuous vs. change-over) treatments (CON SFFA; Meta.1). Regardless design, we evaluated effect treatment PALM MIX; Meta.2) 1-percentage-unit increase MIX in DM (Meta.3). In Meta.1, there no for any variable. Meta.2, CON, had NDF digestibility, milk protein yield energy corrected (ECM), increased yields (1.20 kg/d) fat (0.04 kg/d), decreased (5.20 percentage units). Compared (4.50 units), (1.60 (0.10 ECM (2.00 digestibility. MIX, tended (3.20 (3.50 (0.06 kg/d). Meta.3, each supplemental DM, fat, yield, content, content. For milk, results indicate reason restrictive use change-over designs supplementation studies meta-analyses. Lactating responded better supplement enriched C16:0 one containing C18:0.