Farm Ireland

Wednesday 24 April 2019

Indoor calving a driver of low vitamin D levels in Irish calves

File photo
File photo
FarmIreland Team

FarmIreland Team

New research from Teagasc Grange has highlighted the dangers of Vitamin D deficiency among young calves in Ireland.

Reporting on the research Kieran Meade of Teagasc Grange said the level of calf mortality in Ireland remains high, and therefore, serious research focus has been applied to optimise the nutritional strategies for calves, particularly those raised under artificial systems.

"Optimal immunity requires fuel, and therefore it is logical that calves suffering from malnutrition are more at risk of acquiring multiple infectious and metabolic diseases.

"Interesting research is now showing that programming of the immune system begins pre birth and continues during the early neonatal period, and it is increasingly realised that nutritional or disease insults during this time could have a lifelong impact.

"During this period, as protection from maternal (colostral) antibodies begins to wane, the calf is susceptible to disease until protection via vaccination or natural immunity develops," he said.

According to Meade, Vitamin D is a nutrient that bridges the nutritional and immunological systems by providing the metabolic requirements for growth, as well as the activation and regulation of an immune response.

The two major forms of vitamin D are plant-based dietary vitamin D2 (ergocalciferol) and meat-based and ultraviolet B (sun)-induced vitamin D3 (cholecalciferol).

While the role of the active forms of vitamin D in bone and mineral health has been well established, it is only recently that the diverse mechanisms by which vitamin D influences the immune system are being appreciated.

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Teagasc research has evaluated the levels of vitamin D in Irish neonatal calves for the first time.

While optimal levels of vitamin D have not been established in cattle, values of 30ng/ml are generally thought to be required for optimal health, based on international data.

The results show that it could take four months before Irish spring-born calves reach this threshold, and therefore may have an increased risk of developing disease.

Predominantly in recognition of its benefits to animal performance, vitamin D supplementation is extensively practised in calf rations.

However, Meade says young neonatal calves are not consuming rations, and milk (or milk replacer) is usually their sole source of nutrition.

"Additionally, in spring, when sun intensity is low, and cows calve indoors, it is possible that calves may be susceptible to disease due to a vitamin D deficiency," he said.

Multiple mechanisms may provide opportunities to boost circulating vitamin D levels in calves.

Meade says future research will determine if direct supplementation of the calf, as well as increased levels in the diet of the dam, may provide opportunities to boost their innate immune systems during the important early window of disease susceptibility.

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