Abstract / Summary
Abstract Although telomere length (TL) is increasingly associated with physiological resilience and stress exposure in cattle, it remains unclear whether TL in early life affects later performance, or it is just a marker affected by cumulative genetic, environmental, and physiological factors. Therefore, we investigated in Holstein male calves: (i) the effects of maternal factors on calf TL at parturition; ( ii ) effect of housing on TL dynamics; (iii) associations among TL, endocrine biomarkers, and feed-efficiency across developmental stages; and (iv) whether early-life TL predicts later physiological and production traits. For these aims, relative TL was repeatedly measured in 118 dam-calf pairs, alongside endocrine and feed-efficiency. Dam and calf TL were positively associated at birth (R 2 = 0.29; P ≤ 0.001), while housing was associated with TL dynamics. Early-life feed efficiency (gain-to-feed; G:F) was primarily associated with housing (P = 0.0035). In group-housed calves, G:F was associated with endocrine measures (testosterone, P = 0.0007; cortisol, P = 0.006). In both rearing systems birth TL was positively associated with testosterone at later ages (P ≤ 0.05). TL at 12 months best predicted residual feed intake (P = 0.004). These findings indicate that TL is a dynamic, age-dependent trait, associated with maternal, environmental, and endocrine factors, and may serve as an integrative biomarker of physiological status and metabolic efficiency.