Dry-cow nutrition plays key role in rapid post-calving return of positive energy status
Take Home Message: A modest reduction in body condition of 0.2 units during the dry-period results a similar milk yield but less body fat mobilisation in early lactation which may reduce metabolic problems.
A restricted low energy pre-calving diet significantly reduces body reserve mobilisation post calving and results in a more rapid return to positive energy status. This vital information for dairy producers looking to improve their dry cow management was the conclusion of a study headed by Ryan Law of the UK’s Agri-Food and Biosciences Institute.
His team’s findings concur with previous work that suggested that loss of body condition during the dry period reduced body reserve mobilisation post-calving and, therefore, maintained good liver function. Dr Law’s study also revealed that a restricted low-energy pre-calving diet significantly increased plasma glucose levels post-calving, which may also be indicative of improved liver function.
Prolonged negative energy balance during early lactation predisposes the cow to an increased risk of metabolic disorders, poor fertility and subsequently increased culling rates. “Historically, much emphasis has been placed on post partum nutrition in an attempt to suppress these ill effects. But contemporary theories advocate improved dry cow nutrition to properly prepare the cow for energy demands of early lactation,” Dr Law told delegates attending this year’s British Society of Animal Science annual conference.
“Priming the liver during the dry period would allow the cow to better deal with metabolic processes in the post partum period. In our experiment, dairy cows were offered different dietary energy levels pre- and post-calving in an attempt to quantify the effects on energy parameters during the same time periods,” he added.
The study involved 40 Holstein heifers and 40 Holstein cows that were allocated to one of four treatments: high or low energy density diet pre- and post-calving.
All cows were housed and high and low energy diets were offered ad lib. From day 42 pre-calving, cows receiving the low energy diet were restricted to 6kg DM complete diet/ day, while the high energy pre-calving diet continued to be fed ad lib. Post calving, treatments were balanced for parity, body weight and date of calving. The concentrate:forage DM ratios of the high and low energy density diets post calving were 70:30 and 30:70 respectively, providing 12.5 and 11.7 MJ ME/kg DM.
“Pre-calving dietary treatment had a significant effect on body condition score at calving; on average animals receiving an ad lib high energy diet and a restricted low energy diet had a body condition score at calving of 2.70 and 2.49 respectively.”
Presented to the British Society of Animal Science, Annual Conference, 30 March - 1 April 2009, UK Full details: Law RA, Young FJ, Patterson DC, Kilpatrick DJ, Wylie ARG, Mayne CS: “Effect of dietary energy content pre-and post-calving on production and blood metabolites of dairy cows during early lactation.”
Summary (pdf) Presentation_011law (pdf)
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