Effect of Calcium bolus at calving on postpartum performance and milk composition in dairy cows

Abstract

During the late stages of gestation, calcium requirements increase to support the development of the calf and the production of colostrum. Low blood calcium after calving can result in various issues such as reduced feed intake, decreased milk production, muscle weakness, and in severe cases, recumbency. The study aimed to investigate the effect of calcium supplementation after calving on performance and milk composition of dairy cows during the first 28 days of lactation and lactational performance (days open, lactation length, cumulative lactation milk yield, and 305-d mature equivalent milk). Holstein cows (parity number: 2.6 ± 0.46) were randomly allocated into 2 groups: (1) oral supplement of Calcium bolus (CaB; n= 9) containing calcium formate and lithothamnion calcareum (red coral alga) immediately and 12 - 18 h post-calving and (2) Control (CON; n = 11) that did not receive oral Ca. Milk yield was recorded daily and data of body weights and milk composition were collected weekly from calving to 28 d postpartum. Blood sampling was performed between partum and 72 h from the coccygeal vein after morning milking and before feeding. Ca supplementation at calving tended to increase daily milk yield (P= 0.062) and increase total milk yield (P= 0.049) for 28 d postpartum. Also, CaB treatment significantly increased (P= 0.038) blood total Ca levels (2.15 mmol/L vs 1.87 mmol/L) in the first 72 hours after calving but did not affect magnesium and phosphorus concentrations. However, body weights and milk composition (total solids, fat, protein, fat:protein ratio, lactose, casein and urea-N), and lactational performance (energy and fat corrected milk, fat and protein yields) did not differ between treatments. Also, there was no effect of the treatments on days open, lactation length, 305-d mature equivalent milk, and lactation milk yield. In conclusion, supplementing dairy cows with oral Calcium boluses at parturition improves milk yield during early lactation, but not entire lactation.