Impact of Protected Fat Supplementation on Dairy Performance, Energy Balance, and Blood Metabolites in Early Lactation: A Meta-analysis

Dietary fat provides an efficient energy supply due to its high energy density and low heat increment. This strategy is particularly effective during early lactation, when negative energy balance (NEB) commonly occurs, but the results regarding improvements in dairy performance have been inconsistent. Therefore, this study aimed to evaluate the effect of dietary protected fat in early lactation dairy cows on dairy performance, energy balance, and blood metabolites. A total of 14 articles were selected for the meta-analysis, integrating 31 data points into the database. The data were analyzed using the random effects meta-analysis method, with effect size calculated based on Hedges’d. The parameters were analyzed, including dry matter intake, nutrient digestibility, body weight (BW) and body condition score (BCS) changes, milk yield and composition, energy balance, and blood metabolites. The results showed that dietary protected fat significantly enhanced dry matter (DM) digestibility (65.90% vs. 67.66%, p<0.01), organic matter (OM) digestibility (70.96% vs 72.33%, p<0.01), BW changes (60.47 vs 153.17 g/day, p<0.01), and milk yield (27.79 vs. 29.20 kg/day, p<0.01), while reducing milk fat content (4.04% vs. 3.80%, p<0.05). Dietary protected fat reduced NEFA concentrations (-1.024 vs. -1.527 mmol/L, p<0.01), but it did not significantly affect overall energy balance. In conclusion, protected fat supplementation improved dairy performance and body reserves during early lactation without altering energy balance.