References
Metabolic programming and monitoring tools in pre-weaned dairy calves
Abstract
The current knowledge on the effects of nutritional and environmental factors in the late embryonic and neonatal phase of dairy calves on performance later in life is summarised. The importance of epigenetic factors is increasingly recognised in this context.
Prolonged colostrum feeding, discouraged on most farms to prevent the spread of Johne's disease, can have beneficial effects on the calf's immune system and has been shown to give protection against rotavirus. The importance of colostrum hygiene for uptake of antibodies is explained. Intensive milk or milk replacer feeding leads to a more productive animal while reducing the rearing costs.
Iron deficiency anaemia is a common condition in whole milk fed dairy calves, and monitoring haemoglobin and supplementing iron where necessary leads to higher growth rates in calves. Other monitoring tools like lung ultrasound scanning, and beta-hydroxy-butyrate testing at weaning are briefly introduced. In conclusion, the benefits of many early intervention measures are likely to be underestimated.
On UK dairy farms youngstock rearing is the second biggest cost factor aft er feed costs, and on many farms there are many opportunities to improve welfare and profitability. This article summarises some of the relevant recent research on factors that influence early development with long lasting effects, and gives an overview about available calf health monitoring tools.
Epigenetics describes influences on and effects of differences in gene expression. DNA contains a code made out of genes which encode proteins/enzymes. Proteins are produced in the processes of transcription (production of RNA out of DNA) and translation (production of chains of amino acids based on the RNA sequence in the ribosomes). The DNA sequence is fixed and identical in every cell. However, transcription can occur at variable efficiency, and many steps from the DNA to the protein are dependent on environmental factors. For example, methylation can silence areas of the DNA, and other mechanisms affecting gene expression are known (e.g. histone modification, non-coding RNA) (Chavatte-Palmer et al, 2018) but are beyond the scope of this article. Epigenetic effects are mostly relevant in the embryonic and neonatal stage, and they can be passed on over more than one generation via the maternal or paternal side, with the latter having been over-looked for many years.
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