Effect of Cow Start Calcium Bolus on Metabolic Status and Milk Production in Early Lactation

The objective of this study was to quantify the effect of a combined calcium, magnesium and anti-oxidant bolus on early lactation energy status and milk production performance of multiparous dairy cows compared to control, and calcium only bolus intervention. Multiparous (n=91) cows from a large Irish dairy herd, with a below-average incidence of hypocalcaemia, were enrolled in this study and randomly assigned to either a control (CON, n=30), a calcium only bolus (ABC, n=30) or a combined calcium, magnesium and anti-oxidant (Cow Start calcium) bolus (CSC, n=31). CON cows received no bolus and ABC and CSC cows received two boluses at 0- and 12-hours post-partum. Early lactation energy status was studied by recording milk ketone (beta hydroxybutyrate (BHBA)) levels at day 14 and day 28 post-partum, body condition scoring (BCS) of cows at week 0, 2, 4, 6, 8 and 12 post-partum and by weighing cows at week 0, 2, 4, 6 and 8 post-partum. Cows in the CSC group recorded significantly (P < 0.05) lower milk BHBA levels (0.43 mg/dL) when compared to CON (0.98 mg/dL) and a trend (P < 0.10) towards lower milk BHBA when compared to ABC (0.74 mg/dL). The CSC group also showed a trend (P < 0.07) towards reduced body condition loss between calving and nadir (- 0.39 BCS units) when compared to ABC (- 0.53 BCS units). Milk production volumes were significantly increased (P < 0.05) by 1.3kg per day from day 5 of lactation until day 90 for the CSC group (30.7kg/day) when compared to CON (29.4kg/day), with a trend (P < 0.10) of 0.8 kg per day toward higher milk production when compared to the ABC group (29.9 kg/day). Body weight change (kg), Milk Fat % and kg, Milk Protein % and kg, fat:protein ratio, combined milk components (milk fat and milk protein kg), and energy corrected milk were recorded and analysed, with no significant differences observed. Results of this study indicate that cows supplemented with the CSC bolus responded favourably to treatment with regard to improved metabolic status in the critical early lactation post-partum period when compared to control and a calcium only bolus intervention. Results of this study suggest that supplementing dairy cows with a combined calcium, magnesium and antioxidant oral boluses will have beneficial effects for early lactation dairy cows.