Evaluation of a Brix refractometer to estimate serum immunoglobulin G concentration in neonatal dairy calves.
The objective of this study was to evaluate the utility of a digital Brix refractometer for the assessment of success of passive transfer of maternal immunoglobulin compared with the measurement of serum total protein (STP) by refractometry. Blood samples (n = 400) were collected from calves at 3 to 6d of age. Serum IgG concentration was determined by radial immunodiffusion (RID), and STP and percentage Brix (%Brix) were determined using a digital refractometer. The mean IgG concentration was 24.1g/L [standard deviation (SD) ± 10.0] with a range from 2.1 to 59.1g/L. The mean STP concentration was 6.0 g/dL (SD ± 0.8) with a range from 4.4 to 8.8 g/dL. The mean %Brix concentration was 9.2% (SD ± 0.9) with a range of 7.3 to 12.4%. Brix percentage was highly correlated with IgG (r = 0.93). Test characteristics were calculated to assess failure of passive transfer (FPT; serum IgG <10 g/L). The sensitivity and specificity of STP at 5.5 g/dL were 76.3 and 94.4%, respectively. A receiver operating characteristic curve was created to plot the true positive rate against the false positive rate for consecutive %Brix values. The optimal combination of sensitivity (88.9%) and specificity (88.9%) was at 8.4% Brix. Serum total protein was also positively correlated with %Brix (r = 1.00) and IgG (r = 0.93). Dairy producers can successfully monitor their colostrum management and the overall success of passive transfer using a digital Brix refractometer to estimate IgG concentration of colostrum and calf serum.
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1. Electronic address: sdeelen@uoguelph.ca.
S M
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Deelen
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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Ollivett
Department of Veterinary Microbiology, Western College of Veterinary Medicine, University of Saskatchewan, Saskatoon, Saskatchewan, Canada S7N 5B4; The Saskatoon Colostrum Co. Ltd., Saskatoon, Saskatchewan, Canada S7K 6A2.
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DM
Haines
Department of Population Medicine, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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Leslie
D000818:Animals; D000831:Animals, Newborn; D002417:Cattle; D003126:Colostrum / Q000737:chemistry; D005779:Immunodiffusion / Q000379:methods / Q000662:veterinary; D007074:Immunoglobulin G / Q000097:blood*; D012031:Refractometry / Q000295:instrumentation* / Q000662:veterinary*; D012680:Sensitivity and Specificity
D007074:Immunoglobulin G
calf; immunoglobulin; passive transfer; refractometer