Effect of Cow Start Bolus Supplementation on Early Lactation Health and Performance Indicators in a Group of Older, At-Risk Dairy Cows

Whilst older cows can be some of the most profitable producers on the farm, as well as helping to reduce the environmental impact of dairy production and improving consumer perception of dairy farming, they can also be more prone to early lactation metabolic challenges and at higher risk of culling or death in early lactation. Research into nutritional supplementation strategies specifically to support older, at-risk herd members has not, to the author’s knowledge, been carried out and leaves a dearth of knowledge as to how best to support the successful transition of this valuable cohort of cows from gestation into peak lactation. The objective of this study was to evaluate the effect of supplementation with a combined calcium, magnesium and antioxidant bolus (Cow Start) on key early lactation health and performance indicators in a cohort of older, higher yielding dairy cows that may be expected to be at greater risk of developing key post-partum metabolic disorders. High yielding multiparous (n=38) cows averaging 4.7 lactations at calving were enrolled in this study and randomly assigned to either a control (CON, n=19) group or a Cow Start oral bolus supplemented (CSC, n=19) group. The CON group experienced a clinical milk fever (Blood Ca < 1.5 mM) incidence rate of 15.7% compared to 0% for the CSC group. Cows in the CSC group recorded a treatment effect of a significantly (P < 0.01) higher blood calcium status compared to CON. Energy Corrected Milk volumes showed a statistical trend of an increase (P < 0.10) from day 5 until day 60 of lactation for the CSC group (+1.8 kg/day) when compared to CON, also milk fat kg (P < 0.05) and combined fat and protein kg yields (P < 0.10) were increased in the CSC group when compared to the CON group. Results of this study suggest that supplementation of older at-risk cows with a combined calcium, magnesium and antioxidant (Cow Start) oral bolus can reduce the incidence rate of clinical milk fever and exposure to sub-clinical milk fever, whilst also improving blood calcium status and increasing milk production parameters in early lactation when compared to CON.