217 EFFECT OF FREQUENCY OF MILKING ON POSTPARTUM EVENTS IN SISTANI CATTLE

Abstract

Prolonged postpartum anestrus is a major concern in Bos indicus breeds. Sistani cattle is an Iranian Bos indicus beef breed with more than 5000 years of history in the northwest part of Iran, Sistan. This breed is well adapted to the harsh, arid environment, which includes 120 days of hot winds. Small holders in the Sistan region use Sistani cattle for both meat and milk. The purpose of this study was to investigate the effect of frequency of milking on the postpartum events in this breed. Healthy Sistani cattle (n = 41) with 3.3 ± 0.3 parity and normal parturition were randomly assigned to 3 groups after parturition and were monitored for 3 months. Cows in Groups 1 and 2 were milked once (n = 15) or twice (n = 14) per day, respectively. The control (n = 12) cows were not milked. All cows were allowed to be suckled by their calves once per day. Throughout the 3 months of monitoring after calving, blood samples were collected weekly and assayed for progesterone using RIA. Standing estrus was detected every day at 0700, 1400, and 2100 h. The first rise in progesterone after calving was considered when it was above 1.5 ng/mL. Data were analyzed using GLM procedure in SAS (SAS Institute, Cary, NC). There was no significant difference in the variables measured among groups (P > 0.05); therefore, the data were pooled (Table 1). The number of estrus, the day of the first estrus, and the first rise in progesterone after calving were 2.9 ± 1.42, 31.2 ± 1.77, and 38.8 ± 2.20, respectively (Table 1). Average number of service per conception (1.6 ± 0.12) and days open (94.4 ± 7.63) in Sistani cattle may be considered to be superior reproductive indices to those reported in the majority of Bos indicus breeds. In conclusion, once-daily or twice-daily milking did not influence postpartum reproductive indices of Sistani cattle, indicating that twice-daily milking may be advised to enhance the profitability of small holders. In Sistani cattle, ovarian activity and estrous behavior resumed fairly soon after partition, allowing for earlier conception in this breeds.

Table 1.  Postpartum reproductive indices of Sistani cattle with varying frequencies of milking

This research was funded by the Research Deputy of the University of Tehran and Animal Science Research Institute.