This study was conducted on 47 pluriparous pregnant Egyptian buffalo. Body condition score (BCS) was classified and blood samples were collected pre-partum and post-partum for estimation of IGF-1, hormonal, metabolic and antioxidants values. There was palpation per rectum and ultrasonography in addition to quantitation of progesterone (P4) and estradiol-17β (E-17β) for monitoring post-partum ovarian resumption. Reproductive indices were calculated 60, 90, 120 and 150 days post-partum. Based on the concentrations of P4 and E-17β, buffalo were divided into ovulatory and non-ovulatory groups. The P4 and E-17β were greater (P < 0.001) in ovulatory compared to non-ovulatory buffalo. The BCS and IGF-1 post-partum were greater (P = 0.024; 0.001, respectively) in ovulatory than non-ovulatory buffalo. Glucose and albumin were greater during pre- (P < 0.001; 0.013) and post-partum (P = 0.005; 0.003) periods in ovulatory than non-ovulatory buffalo. Post-partum, NEFA and BHBA concentrations were greater (P < 0.001) in non-ovulatory than ovulatory buffalo. The BUN concentrations were greater (P = 0.002) in non-ovulatory buffalo during pre- and post-partum periods. There were differences in GSH and SOD concentrations between groups (P < 0.001; 0.002, respectively). The BCS, albumin, IGF-1, GSH and SOD concentrations post-partum were negatively correlated with the delay of post-partum ovulation. The post-partum NEFA and BHBA concentrations, however, were positively correlated with delayed post-partum ovulation. Ovulatory buffalo had fewer (P < 0.01) days non-pregnant and for calving intervals as well as greater pregnancy rates than non-ovulatory buffalo. In conclusion, buffalo with delayed post-partum ovarian resumption were prone to have negative energy balance.