Abstract
The objective of this study was to evaluate both the safety, and efficacy of supplementation at calving with a combined oral calcium and anti-oxidant bolus on post-partum metabolic status, fresh cow energy status, vaginal mucous score and early lactation milk production performance. Multiparous (n=103) cows from 3 dairy herds in Ireland were enrolled in this study and randomly assigned to either a control (CON, n=51) group or an oral bolus supplemented (BOL, n=52) group. CON cows received no oral boluses. BOL cows received 2 oral boluses, at 0 and 18 hours (hrs) after calving. Cows were fed a standard dry cow diet of second cut grass silage with supplemental pre-calving minerals, and fewer than 2.3% of all fresh cows (n=899) in these herds were treated for clinical milk fever (below target incidence level). Trial-eligible cows treated with IV calcium at calving were excluded from the trial. No adverse events associated with bolus safety were observed. The bolus was adminstered with ease and was well-tolerated by all animals. Calving and early lactation disease events were recorded. Metabolic status was evaluated by using milk ketone (beta hydroxybutyrate (BHBA)) testing at day 14 and day 21 post-partum. Cows in the BOL group recorded significantly lower milk BHBA levels (0.46mg/dl) compared to CON cows (0.67mg/dl), (p<0.0001). Milk yield, Milk Fat % and kg, Milk Protein % and kg, combined milk components (milk fat and milk protein kg) and somatic cell counts (SCC) were recorded but no significant differences were observed. Results of this study indicate that the bolus is safe to use in post-partum dairy cows. Furthermore, cows responded favourably to treatment with the bolus with regard to improved metabolic status in the critical post-partum period. Results of this study suggest that supplementing dairy cows with oral boluses can have beneficial effects, even in dairy herds with a below-average incidence of hypocalcaemia.
Highlights
Hypocalcaemia, characterised by a decrease in blood calcium of the cow, is a common and costly metabolic disease of dairy cattle in the peri-partum period
The cow experiences a rapid increase in calcium demand for colostrum and milk production, the ability of the cow to match this increase in demand can be delayed by 24 – 48 hours
Overall herd performance for the 2018 spring calving season showed that these herds were under excellent management and were not subject to higher than average levels of hypocalcaemia, and all 3 herds were well below threshold incidence levels for the major transition cow disorders [22] (Table 1)
Summary
Hypocalcaemia (milk fever), characterised by a decrease in blood calcium of the cow, is a common and costly metabolic disease of dairy cattle in the peri-partum period. The cow experiences a rapid increase in calcium demand for colostrum and milk production, the ability of the cow to match this increase in demand can be delayed by 24 – 48 hours. The excess calcium required is sourced from her digestive and skeletal systems through an upregulated calcium metabolism but the time delay between the sudden increase in demand and an increase in supply, results in a failure of the cow to maintain calcium homeostasis. Typical levels of clinical hypocalcaemia in dairy herds from various management systems are reported to be between 5 – 7% [1, 3, 4].
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