Cows in metabolic stress have calves with lower body weights at birth and the calves’ immunity is negatively affected.
A recent article has shown that cows with higher fat mobilisation in late pregnancy or greater oxidative stress (an indicator of immune stress) produce lower body weight calves. Also, immune cells taken from these calves in early life show less ability to react to microbial attack.
How was this discovered?
In this experiment by a group from Australia & Michigan State, 12 multiparous Holstein-Friesian cows were chosen with either normal, or stress-indicated markers in blood (non-esterified fatty acids, haptoglobin or oxidative stress indicators – OSi). Their calves were weighed at birth and at 4 weeks old and blood was taken from the calves at 7, 14, 20 and 29 days of age. The blood was measured for signs of how the immune cells responded to lipopolysaccharide (LPS) stimulation by the production of tumour necrosis factor alpha (TNFalpha). LPS is a molecule found in the outer coat of Gram negative bacteria, such as E. coli and TNFalpha is a substance produced by the immune system when it is under attack from microbes (an acute phase protein).
Cows with high NEFA and OSi had calves which were avg. 2 to 3kg LESS from calving to 4 weeks of age.
Calves from cows with high NEFA and OSi had cells with less ability to react to TNFalpha when stimulated by LPS.
What does this mean for Dairy Health?
This research implies that cows that are managed to have less metabolic and immune stress (less disease and less energy deficits) in their dry period can not only better protect themselves in early lactation but also have beneficial effects on the health of their calves.