Twenty-one lactating Egyptian buffalo cows weighing 550-600 kg, aged 4-6 years and between 2-4 parities were divided into three experimental groups. All animals were fed basal diets containing corn silage; berseem hay, rice straw and concentrate feed mixture. The 1st group (control) was fed the basal diet without any supplementation, while the 2nd (G1) and third (G3) were daily supplemented with 20 g yeast culture (Gustor nature) and 20 g Gustor nature plus 35 g premix, respectively. The supplementation started one-month pre-partum and continued 6 months post-partum. Period elapsed from calving until each of placental drop and uterine involution. Also, reproductive measurements were recorded. Results revealed that mean period elapsed from calving until placenta drop significantly (P<0.05) decreased in G1 and G2 (5.07 and 4.64 h) than control group (8.14 h). The interval required for each of pregnant uterus to return intra-pelvic, postpartum cervical closure and uterine horns symmetry were earlier (P<0.05) in G1 (16.7, 24.0 and 25.7 d) and G2 (15.4, 24.4 and 22.7 d) than control group (29.5, 37.7 and 38.0 d), respectively. Buffalo cows in G1 and G2 showed higher intensity of oesrous activity (62.5 and 62.9%) than control group (44.5%). First postpartum ovulation interval was earlier (P<0.05) in G2 (20.3 d) than in G1 (29.0 d) or control group (30.0 d). First postpartum oestrus interval was insignificantly detected earlier in G1 (34.5 d) than in control (41.3 d) or G2 (44.6 d). Postpartum first service interval was insignificantly lower in the control group (41.3 d) than in G1 (42.6 d) or G2 (47.8 d). Average values of service period were 0, 3.5 and 12.3 d; number of services/conception was 1.0, 1.17 and 1.33; days open were 42.6, 51.3 and 54.2 d, and calving interval was 358, 364.7 and 373.2 d in G1, G2 and the control group, respectively, but the differences were not significant. Within the first 50 days postpartum, conception rate was 83.3, 66.7 and 50% in G1, G2 and the control group, respectively. Overall mean of ovarian cycle length was 22.2, 21.1 and 19.7 d; and number of ovarian cycles was 0.66, 1.5 and 0.83/buffalo cows in G1, G2 and the control group, respectively.
It could be seen that diet supplemented with 20 g Gustor nature/head/day (G1) during a month pre-partum and continued 6 months post-partum improved reproductive performance of Egyptian buffalo cows in terms of low number of services/conception, short service period length, less number of days open and short calving interval.