Received: August 18, 2016; Revised: September 22, 2016. Accepted: November 2, 2016. Published online November 3, 2016.
Objective: 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. Method: 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. Bioinformatics 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. Results: There were 57 differential spots separated and eight different proteins were identified. Vitamin Dbinding protein precursor (groupspecific component, GC), alpha2macroglobulin (A2M) protein, and apolipoprotein AIV were related to hypocalcemia by bioinformatics analysis. Due to its specific expression (upregulated in clinical hypocalcemia and downregulated in subclinical hypocalcemia), A2M was selected for validation. The results were consistent with those of proteomic analysis. Conclusion: A2M was as an early detection index for distinguishing clinical and subclinical hypocalcemia. The possible pathogenesis of clinical hypocalcemia caused by GC and apolipoprotein AIV was speculated. The downregulated 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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