Fat supplement for dairy cows during early lactation – potentials, challenges, and risks – a meta-analysis

The most critical challenge in early lactation is to meet the increasing energy demand for milkproduction, which results in a negative energy balance (EB). The objective of this study was toevaluate the productive performance and plasma metabolite responses of early lactating dairy cowsfed diets supplemented with increasing levels of different fat sources. Diets were categorized as dietssupplemented with saturated fatty acid rich fat sources (SFAR), with Ca-soaps of fatty acids (CaFA),and with polyunsaturated fatty acid rich fat sources (PUFAR). There was an interaction between crudefat level and source for dry matter intake (DMI); each percentage-unit increase reduced DMI by 0.38and 0.77 kg/d in CaFA and PUFAR, respectively, and increased DMI by 0.55 kg/d in SFAR. Correctedmilk yield increased by 0.44 kg/d for each percentage-unit increase in crude fat level. Plasma non-esterified fatty acid (NEFA) concentration increased with 0.04 mmol/L per percentage-unit increase. Inconclusion, the increased crude fat level increased corrected milk yield. Fat supplementation in earlylactation does not seem to cause negative effects on productive performance or metabolism, anddespite a small increase, both plasma NEFA and β-hydroxybutyrate (BHB) concentrations stayed belowthe threshold for incidence of subclinical ketosis.