Effect of enhanced early life nutrition on hypothalamic arcuate nucleus miRNA transcriptome in bull calves.

The aim of this study was to measure the impact of contrasting feeding regimes in the first 12 wk of life, on the molecular control of hypothalamic arcuate nucleus tissue in bull calves. Holstein bull calves were designated to high (HI; n=15) or moderate (MOD; n=12) dietary groups, with diets designed to provoke growth rates of 1.0 and 0.5 kg/day, respectively. At 12 wk of age, all calves were euthanized, and hypothalamic arcuate nucleus tissue harvested. RNA was extracted from the hypothalamic arcuate nucleus and used for miRNAseq. In total 30 RNA samples were analysed, 15 samples were derived from bull calves fed the High plane of nutrition (HI, n=15) and 15 samples were derived from the calves fed the Moderate plane of nutrition (MOD, n=15). From 2 weeks of age calves on the High-plane of nutrition received 1.5 kg of milk replacer (10 liters) per day and ad libitum concentrates, whilst te MOD group received 0.5 kg of milk replacer (4 litres) per day and 0.5 kg of concentrates. Tissue samples were collected from all calves at 12 weeks of age.