PSX-B-9 A Nanotechnology Base Immunity Measurement (D2Dx) Compared with Total Serum Protein Concentration Using Neonatal Holstein Bull Calves

Abstract

Abstract The D2Dx immunity test (Nano Discovery Inc.) is a nanotechnology-based assay for quantifying the immune responses to foreign pathogens. In contrast, the measurement of total serum protein (TSP) concentration is used to determine the passive immunity status of neonatal calves. Inadequate colostrum feeding increases the risk of calves having increase disease challenges thereby reducing growth performance and possibly death. Our operation routinely sources 2- to 5-day old Holstein bull calves from numerous Wisconsin sale barns for evaluating nutritional programs and feed additives. The study objective was to compare the D2Dx immunity test with TSP concentration for evaluating the immunity and status of passive immunity of calves. Two 2021 calf studies conducted during summer and fall consisting of 160 total calves (80 calves per study) had 8-10 mL blood samples collected via jugular puncture within 1 day of arrival. Blood serum was immediately analyzed for TSP concentrations using a digital refractometer. Samples were then frozen and later thawed to room temperature for collecting D2Dx measurements. Pearson correlation coefficients were calculated using SAS version 9.4. The D2Dx test was highly correlated with TSP concentrations (r = 0.61, P < 0.01) across both studies indicating the D2Dx test can be used to assess status of passive immunity. The correlation coefficient did vary by study ranging from r = 0.54 (P < 0.01) for summer sourced calves to r = 0.65 (P < 0.01) for fall sourced calves. Average daily gains (ADG) were less (P < 0.01) for summer compared with fall sourced calves (0.692 and 0.853 kg/d for summer and fall, respectively). There was little correlation between passive immunity measurements (D2Dx and TSP) with ADG (r = < -0.04, P > 0.10). The D2Dx test can be used to assess transfer success or failure of passive immunity in neonatal Holstein bull calves.