Progesterone, Oestradiol, and Cortisol Interactions During Anoestrus in Suckling Cows in Adamawa State

Post-partum anoestrus is a major constraint on reproductive efficiency in suckling beef cows in Nigeria, particularly in Adamawa State, North East Nigeria, where the Adamawa White Fulani and Sokoto Gudali breeds are extensively managed under rangeland conditions with seasonal nutritional challenges. The suckling stimulus suppresses pulsatile GnRH and LH release, prolonging post-partum anovulation, while negative energy balance associated with lactation and dry season nutritional shortfalls further exacerbates hypothalamic suppression. This study characterised the hormonal interactions between progesterone, oestradiol-17 beta, and cortisol during post-partum anoestrus in 50 suckling cows at farms in Yola and Numan, Adamawa State. Blood samples were collected twice weekly for 16 weeks post-partum and hormones were measured by validated ELISA. Ultrasonographic follicular monitoring was performed concurrently. Interval to first ovulation post-partum was recorded as the primary outcome. Cows with body condition score of 2.5 or below at calving had significantly longer anoestrus periods of 14.3 weeks compared with 9.8 weeks in better-conditioned cows. Cortisol concentrations were significantly elevated in prolonged anoestrous cows and showed a negative correlation with oestradiol. Follicular growth was impaired in high-cortisol animals, with dominant follicles failing to reach the ovulatory threshold. Early weaning at week eight significantly shortened anoestrus duration compared with continued suckling. These findings illuminate the endocrine basis of post-partum anoestrus in suckling cows in Adamawa and provide a hormonal rationale for nutritional and management interventions to shorten the inter-calving interval. Keywords: post-partum anoestrus, progesterone, cortisol, suckling, Adamawa State.