Effect of Oxytocin Administration or Natural Early Uterine Involution on Reproductive Traits, Progesterone Profile, and Milk Production of Friesian Cows

The present study aimed to compare reproductive performance, milk yield, and progesterone profile of Friesian cows diagnosed with late uterine involution (UI), natural early-UI, and those induced to early-UI by oxytocin (OXY). At calving, total of 30 normal multiparous lactating Friesian cows the experimental animals (n=30) were divided into two groups, one group (control, n=20) which were left normally without treatment up to complete UI, and another group (n=10) were i.m injected with 50 IU of OXY within 6-12 hours after parturition. Results showed that mean duration of UI was earlier (P<0.05) in early UI and OXY groups by 22.2 and 18.8% as compared to late UI. Estrus/service rate (ER) increased (P<0.05) in OXY as compared to late-UI, but did not differ significantly in early-UI. Postpartum 1 st estrus PPFEI and service (PPFSI) intervals were shorter (P<0.05) in early-UI than in late-UI and OXY groups. Service period was lower (P≥0.05) in early-UI and OXY than in late-UI groups. Days open was lower (P<0.05) in early-UI than in late-UI. Pregnancy rate (PR) was higher (P<0.05) in early-UI and OXY than in late-UI. Reproductive index was higher in OXY than in late-UI (63.39 vs. 42.33%, P<0.05), and in early-UI than in late-UI (46.99 vs. 42.33%, P≥0.05). Milk production (weekly, daily, and total) was not affected. Early uterine involution naturally in lactating cows or inducing early uterine involution by oxytocin within 24 h of calving have a beneficial effect on the reproductive performance of lactating cows without adverse effect on milk production.