In two commercial dairy farms outside Tehran, researchers found that the blood of a cow in the weeks surrounding birth carries a legible record of her reproductive future. A study of 366 Holstein cows revealed that measurable metabolic imbalances — in fatty acids, ketones, minerals, and proteins — reliably predict dystocia, ovarian failure, uterine infection, and early culling. The transition from pregnancy to lactation emerges not merely as a biological passage, but as a narrow window of vulnerability in which the chemistry of survival and the chemistry of fertility are deeply, dangerously in