Abstract
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.
Highlights
At parturition the cow experiences significant challenges to calcium homeostasis, brought about by a rapid increase in demand for calcium to support colostrum and milk production
Milk Beta Hydroxy Butyrate (BHBA) Milk BHBA analysis demonstrated that the Cow Start Calcium (CSC) group had significantly lower milk BHBA levels compared to CON at day 14 and day 28 (P < 0.05) and that the CSC group showed a statistical trend for lower milk BHBA levels at day 14 and day 28 compared to ABC (P < 0.10) (Figure 1)
The results of our study demonstrate that cows that received the Cow Start Calcium bolus had improved early lactation metabolic status based on lower milk BHBA and less body condition loss in early lactation, when compared to control and calcium-only bolus treatment groups
Summary
At parturition the cow experiences significant challenges to calcium homeostasis, brought about by a rapid increase in demand for calcium to support colostrum and milk production. Hypocalcaemia reduces rumen and abomasal motility increasing the risk of displaced abomasum [1] This reduction in DMI coincides with a dramatic rise in energy demand as the cow enters milk production, which results in an unavoidable period of negative energy balance. In order to address this energy shortfall, the cow must mobilise body fat reserves from adipose tissue Ketones, such as nonesterified fatty acids (NEFA) and β-hydroxybuytric acid (BHBA) are byproducts of this process and are routinely monitored as markers for the energy status of the cow, with higher levels of NEFA or BHBA reflecting higher degrees of lipid mobilisation and more critical states of ketosis. Numerous studies have found a correlation between low blood calcium status and elevated levels of circulating ketones (NEFA and BHBA), indicating that compromised calcium status in early lactation may lead to greater energy deficit in the critical transition period [2, 7, 8]. Prevalence of sub-clinical ketosis is reported at rates of between 10% and 40%, and associated with production and profitability losses of US$289 per cow [9, 11,12,13,14]
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