Many of the cited works report improvements in metabolic, immune, and oxidative stress markers following supplementation with rumen-protected methionine, choline, glutamine, or fatty acids. Yet, the variation in dosage, timing (e.g., prepartum vs. postpartum), duration, and even delivery methods (e.g., abomasal infusion, dietary inclusion, bolus form) raises the question: How do the authors reconcile these inconsistencies when comparing outcomes or making practical recommendations for field application? Moreover, while improvements in markers like NEFA, βHBA, cytokines, or GSH are repeatedly highlighted, did any of the studies include long-term monitoring post-transition or evaluate potential carry-over effects on fertility, lactation persistency, or longevity? Without this, how can we be certain that short-term physiological improvements translate into meaningful welfare or economic benefits at the farm level?
