Received: 18 August 2016; Revised: 22 September 2016. Accepted: 2 November 2016. Published online 3 November 2016.
Hypocalcemia is an important metabolic disease of dairy cows during the transition period, although the effect of hypocalcemia on biological function in dairy cows remains unknown. In this study, proteomic, mass spectrum, bioinformatics and western blotting were employed to identify differentially expressed proteins related to serum Ca concentration. Serum samples from dairy cows were collected at three time points: 3rd days before calving (day -3), the day of calving (day 0), and 3rd days after calving (day +3). According to the Ca concentration on day 0, a total of 27 dairy cows were assigned to one of three groups (clinical, subclinical, and healthy). Samples collected on day -3 were used for discovery of differentially expressed proteins, which were separated and identified via proteomic analysis and mass spectrometry. Bioinformatic analysis was performed to determine the function of the identified proteins (Gene Ontology and Pathway analysis). The differentially expressed proteins were verified by western blot analysis. There were 57 differential spots separated and eight different proteins were identified. Vitamin D-binding protein precursor (GC), alpha-2-macroglobulin (A2M) protein, and apolipoprotein A-IV were related to hypocalcemia by bioinformatic analysis. Due to its specific expression (up-regulated in clinical hypocalcemia and down-regulated in subclinical hypocalcemia), A2M was selected for validation. The results were consistent with those of proteomic analysis. The down-regulated expression of GC was a probable cause of the decrease in calcium concentration.
Asian-Australasian Association of Animal Production Societies(AAAP)
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