HomePhilippine Journal of Veterinary Medicinevol. 40 no. 2 (2003)

Effect of Intramuscular Injection of Long-Acting Penicillin on the Reproductive Performance of Postpartum Dairy Cows

Antonio A. Rayos | Conrado A. Valdez | Barry V. Alvarez | Demetrio B. Marcial Jr.

Discipline: Veterinary Medicine



A total of 24 postpartum cows were used to determine the effect of intramuscular injection of long-acting penicillin on their reproductive performance. They were grouped into treatment and control according to parity and age. Ten of the 12 (83.3%) antibiotic-treated cows had complete uterine involution 30 days postpartum compared to 75% for the control. Mean calving to first estrus and mean calving to first service intervals were shorter for the treatment group at 57.1 and 66.6 days, respectively compared to the control group at 66.9 and 68.6 days, respectively. Moreover, 50% of the treated cows conceived at first service compared to 33.3% for the control. The results showed that cows injected with penicillin postpartum may have better reproductive performance.