Color Measurement as potential Tool for Determination of Colostrum Quality in primiparous and multiparous Dairy Cows

Abstract Text: Instruments for on-farm determination of colostrum quality like refractometers and densimeters are increasingly used in dairy farms. The colostrum color is also supposed to reflect its quality. A pale or mature milk like color is associated with a lower colostrum value compared to a more yellowish and darker color. The objective of this study was to elucidate the relationships between color measurements (CIE L*=from white to black, a*=from red to green, b*=from yellow to blue) and colostrum quality as assessed by two common on-farm instruments and composition in colostrum in cows and heifers. Thirteen primiparous and twelve multiparous cows were milked for the first time exactly 4 h post-calving. Colostrum was analyzed for total IgG by ELISA and for fat, protein and lactose by a FTS Infrared Milk Analyzer (Bentley Instruments Inc., Chaska, MN, USA) (previously validated for use with colostrum). A Brix sugar refractometer (BRIX) and a Kruuse colostrum densimeter (DENS) were used to assess colostrum quality at 20°C. For color measurements of colostrum samples, a calibrated spectrophotometer (Microflash 200d, Data-color International) was used. In primiparous cows, the total IgG concentration was poorly correlated with L*, a*, and b* (r=-0.13, 0.02, and 0.12; P>0.05), while in multiparous cows correlations were higher (-0.40, 0.32, and 0.06, resp., P>0.05). While DENS did not correlate with color measurements, BRIX was closely correlated with L* (r=-0.68, P<0.01), and b* (r=0.55, P<0.0001) in primiparous and for b* in multiparous cows (r=0.52, P<0.001). Milk fat concentration was correlated with a* (r=0.42, P<0.001, and r=0.44, P<0.001, for primi- and multiparous cows) and b* (r=0.27, P<0.05, and r=0.43, P<0.01), while milk protein concentration was more correlated to b* (r=0.53, P<0.0001, and r=0.30, P<0.05). Highest correlations were found between milk lactose percentage and b* in primiparous (r=-0.59, P<0.0001) and multiparous cows (r=0.56, P<0.0001). In conclusion, the color measurements via spectrophotometer were closest correlated with milk fat, protein and lactose concentrations in colostrum but only to a lesser extent with total IgG concentration colostrum of primiparous cows. An implementation of color measuring devices in automatic milking systems might be a potential instrument also to access colostrum quality besides detecting abnormal milk.

Keywords: Colostrum, color, quality