Method: Assessing ewe robustness using body condition score stability and total lamb weaning weight in extensive systems

Understanding how ewes cope with environmental and physiological challenges is essential for improving flock robustness in extensive production systems. This study evaluated body condition score ( BCS ) dynamics throughout the production cycle as indicators of resilience and examined their association with productive performance at weaning. Three BCS stability metrics were calculated: variance of deviations, lag one autocorrelation, and skewness. In this sense, robustness in productive systems where body traits recording is not daily is defined as a combination of greater BCS stability (high resilience) with productivity performance above the average of the batch. These indicators were then combined with the lamb total weaning weight adjusted for sex of lamb, rearing order, age of dam, breed of dam, and breed of sire ( TWW_adj ) to classify ewes according to robustness. Spearman correlations revealed weak or non‑significant associations between BCS stability indicators and productive performance, while moderate correlations were observed among BCS traits. Despite the limited direct relationships, integrating TWW_adj with BCS stability metrics allowed the identification of distinct robustness categories, which differed in average weaning weight not adjusted and total weaning weight not adjusted, BCS at mating, and monthly BCS variation. These findings highlight the value of combining BCS stability metrics (as a resilience trait) with key productivity traits (TWW_adj) to more accurately identify superior ewes. To be classified as robust, an ewe must exhibit a more stable BCS and maintain a TWW_adj above the flock average. Such an integrated evaluation supports more balanced selection strategies, offering a reliable framework for identifying optimal replacement candidates while improving adaptation and sustainability in extensive sheep production systems.