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Effect of calfhood nutrition on insulin kinetics and insulin signalling pathway genes in muscle
Kelly, A. K. Byrne, C. Keogh, K. McGee, M. Kenny, D. A.
Kelly, A. K.
Byrne, C.
Keogh, K.
McGee, M.
Kenny, D. A.
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Abstract
The objectives of this study were to examine systemic insulin and glucose responsiveness to a glucose tolerance test
(GTT) and transcript abundance of genes of the insulin signalling pathway in skeletal muscle in calves offered an
enhanced plane of nutrition from 3 to 21 weeks of life. Angus × Holstein-Friesian heifer calves (19±5 days of age,
BW: 51.2±7.8 kg, mean ± SD) were offered either a high (HP, n=15) or moderate plane of nutrition (MP, n=15) from
3 to 21 weeks of age. Target growth rates were 1.2 kg/d and 0.5 kg/d, for HP and MP groups, respectively. At 19 wk of
age a GTT was performed and at 21 weeks of age all calves were euthanized and skeletal muscle tissue was harvested
and RNA-Seq analysis was performed. No difference was detected between treatments for area under curve (AUC)
at 60 min for blood glucose concentrations. However, clearance rate of blood glucose was faster (P<0.05) for calves
from the HP versus those on the MP diet. Calves on HP diet had a greater AUC at 60 min for blood concentrations
of insulin compared MP diet. The change in systemic insulin from max to basal levels were greater for HP than MP
dietary treatments, and a faster clearance rate of blood insulin (P<0.05) was observed in HP compared to MP diet.
There was no evidence of insulin sensitivity differences (P>0.10) between the dietary treatments, nor an association
between insulin sensitivity index with early life calf growth. Genes of the insulin signalling pathway involved in fatty
acid synthesis were up-regulated, while genes involved in glucose metabolism were down-regulated in HP compared
to MP calves, suggesting a greater requirement of nutrients in the skeletal muscle of MP treatment calves. Taken
together, these results indicate that a high plane of nutrition up to 21 week of age does not negatively impact insulin
responsiveness in calves.