Leptin Concentrations and Their Relationship with Body Reserves and Reproductive Performance in Sahiwal Crossbred Cows in Edo State

Leptin, an adipokine secreted by adipose tissue in proportion to fat mass, plays a pivotal role in regulating energy balance, reproductive function, and immune competence in dairy cattle. In Sahiwal crossbred cows maintained on peri-urban dairy farms in Edo State, South South Nigeria, the relationship between leptin concentrations, body condition reserves, and key reproductive outcomes has not been studied. This study measured plasma leptin concentrations longitudinally across three physiological stages including dry period, early lactation, and mid lactation in 60 Sahiwal crossbred cows at farms in Benin City and Uromi. Concurrent measurements included body condition score, dry matter intake, and daily milk yield. Reproductive performance parameters including days to first oestrus post-partum, days to conception, and pregnancy rate per service were recorded. Leptin concentrations were highest during the dry period and declined significantly in early lactation, coinciding with peak negative energy balance. Cows with leptin concentrations above 4.5 ng/mL during the dry period showed earlier resumption of oestrous cyclicity post-partum, with a mean interval to first oestrus of 38.2 days compared with 57.4 days in cows with lower leptin. Pregnancy rate per service was significantly higher in high-leptin cows at 62.5 percent versus 41.2 percent. Body condition score at calving correlated positively with leptin. These findings confirm the relevance of leptin as a nutritional and reproductive biomarker in Sahiwal crossbreds under South South Nigerian conditions and support strategic pre-calving nutritional management to optimise post-partum reproductive performance. Keywords: leptin, body condition, reproductive performance, Sahiwal cattle, Edo State.