The Novel Dry Cow project aims to develop an innovative feed concept for transition cows with beneficial effects on health, mainly focusing on preventing (sub)clinical hypocalcaemia.
Health problems in dairy cattle often relate to disorders in the transition phase (dry period and periparturient phase). As a result, compromised animal wellbeing, early culling and decreased dairy cow lifespan are observed at a large number of dairy farms. High-yielding dairy cows on Dutch and Northern American farms are milked on average for less than three lactations, and most cows leave the farm before the age of 6 years (CRV, 2013; Hare et al., 2006).
Recent scientific literature and insights in metabolic health improvement indicate that especially some management measures in the close-up phase offer opportunities to decrease periparturient disorders and to improve a healthy lactation phase.
A pilot study by De Heus evaluated blood calcium, NEFA and BHBA on 7 dairy farms. The outcomes revealed substantial subclinical disease incidence rates. This study was executed on large, well-managed farms with optimal transition rations. Clinically, the disease incidence was low on these selected farms, but the blood values indicated subclinical problems with hypocalcaemia. Despite all the measurements taken at the management level and ration optimisation, there still is a serious need for improvement.
Novel Dry Cow concept
To prevent the risk of (sub)clinical hypocalcaemia, lowering DCAB in the close-up phase is a widely used strategy. However, using low DCAB diets itself will reduce dry matter intake prepartum, especially when anionic salts are used in high amounts. Due to the nature of the grass silage, a large amount of anionic salts is necessary to decrease the diet DCAB to a level that induces acidity of the urine. This eventually will increase urinary calcium excretion and restore the sensitivity of tissues to parathyroid hormone. In this study a new, very palatable source of anionic salts will be used. The product however has never been assessed in Europa, nor in grass silage based dry cows diets which are typical for many Dutch dairy farms. The product will be included in a compound feed, where energy, protein as well as methionine levels are optimized to prepare transition cows for the next lactation. In this study the source of anionic salts will be evaluated at the appropriate DCAB level that induces urinary calcium excretion, as well as the DCAB level that is reached in practice nowadays. As a control a low energy prepartum diet will be used.