Abstract

Background:
The transition period in dairy cows, covering approximately 3 weeks before and after calving, represents a physiologically demanding phase characterized by profound metabolic and endocrine adjustments that strongly influence subsequent health and fertility.

Aim:
This study aimed to evaluate the effects of oral calcium propionate (CP) and/or intramuscular 1,25-dihydroxyvitamin D3 (VitD3) supplementation on calving-related disorders, blood metabolites, and reproductive performance in Friesian dairy cows during this critical period.

Methods:
Forty multiparous cows were randomly assigned to four groups (n = 10 each): control (no supplementation), CP (125 g twice weekly, orally), VitD3 (10,000 IU once weekly, intramuscularly), and a combined CP + VitD3 group. Supplements were administered for 4 weeks before and after parturition.

Results:
Compared with the control group, cows supplemented with CP and/or VitD3 exhibited a significant improvement in uterine involution rate, time of placental expulsion, and duration of lochial discharge. The combined CP + VitD3 treatment resulted in earlier placental separation, a shorter duration of uterine involution, and a lower incidence of postpartum disorders, such as dystocia, retained placenta, uterine prolapse, abnormal lochia, endometritis, hypocalcemia, and repeat breeding. Moreover, treated cows showed higher serum glucose, calcium, total protein, and IgG concentrations, alongside lower cortisol, NEFA, and AST activities, indicating improved metabolic adaptation and hepatic function. Reproductive performance was markedly enhanced, as reflected by a shorter interval to first estrus, reduced days open, fewer services per conception, and a higher conception rate, particularly in cows receiving the combined treatment.

Conclusion:
In conclusion, concurrent supplementation with CP and VitD3 during the transition period effectively enhances metabolic stability, mitigates periparturient complications, and substantially improves reproductive efficiency in Friesian dairy cows.

Key words: 1,25-dihydroxyvitamin D3; Calcium propionate; Friesian cows; Metabolic profile; Reproductive performance.