This experiment was performed to eva‎luate the effects of feeding calcium bolus immediately after calving on blood elements and metabolites, metabolic diseases, and reproductive performance of fresh multiparous cows that had metabolic diseases in the previous calving. For this purpose, 60 Holstein cows, experiencing at least a metabolic disorder in the previous lactation, were selected and divided into two treatments; cows receiving no calcium bolus (control; average milk yield of 42 kg) and cows received calcium bolus (average milk yield of 42.7 kg). Each bolus containing 43 g of calcium was fed immediately after calving and 12 h post-calving. The results showed that feeding calcium bolus increased serum calcium concentration 24 h after calving (6.72 vs. 5.83 mg/dL; P <0.005). This experiment showed that feeding calcium bolus had no significant effect on blood phosphorus (4.13 vs. 4/13) and magnesium (2/25 vs. 2.068) concentrations at 24 h post-calving. There was no difference in the incidence of milk fever, retained placenta, and mastitis between treatments, but bolus feeding decreased the incidence of metritis (2.8 vs. 12) and displaced abomasum (1.1 vs. 5.2). Serum BHBA concentration was lower in cows received calcium bolus compared to control cows (0.633 vs 0.869 mmol/d; P < 0.005). Pregnancy per artificial insemination was not affected by calcium bolus feeding (2.13 vs. 2.4). Cows that received calcium bolus had lower days to first service than control treatment (71.04 vs. 75.44 d; P < 0.05). Cows that received calcium bolus produced more milk compared to control treatment (49.4 vs. 43.5 kg; P < 0.005) during the first 40 days of lactation; however, milk production was not different between treatments from day 40 to 60 of lactation (55.7 vs. 58.9 kg). The culling rate was lower in cows that received calcium bolus during the first 21 days of lactation, but it did not differ between treatments during the first 180 days of lactation (24.14 vs. 13.79). The present study showed that calcium bolus feeding to cows experiencing at least a metabolic disorder in the previous lactation improved blood calcium concentration and decreased blood BHBA concentration, decreased culling rate, and enhanced milk production and some reproduction outcomes.

غلامرضا قرباني، ابراهيم قاسمي

احمد رياسي، فرزاد هاشم زاده

مسعود عليخاني، رسول كوثر