PSI-5 - Relationships of color and viscosity with colostrum yield and quality in beef cattle

Abstract: We hypothesized that color and viscosity are indicative of colostrum yield and quality in beef cattle. Colostrum data from 150 beef females over 6 experiments were combined. In each experiment, single rear quarter colostrum yield was obtained post-calving but pre-suckling. Colostrum IgG was determined by ELISA, and colostrum lactose, triglycerides (as a measure of total fat), and protein were determined by colorimetric analyses. Objective color measurements L*, a*, and b* were determined using a Hunter MiniScan EZ colorimeter on thawed colostrum samples in whirlpak bags. Viscosity score (1 = watery, 5 = thick) was determined visually by 2 trained technicians. Pearson correlation coefficients were determined between color values and colostrum parameters. Mixed models were used to determine the effect of viscosity score on colostrum yield and quality, with experiment as a random effect. L* was moderately positively correlated (r = 0.48, P < 0.001) with lactose concentration, but moderately negatively correlated (r = -0.40, P < 0.001) with protein concentration and weakly negatively correlated (r = -0.34, P < 0.001) with IgG concentration. Both IgG (r = 0.42) and protein (r = 0.50) concentrations had a moderate positive relationship (P < 0.001) with a*. Colostrum a* also had a moderate negative relationship (r = -0.49, P < 0.001) with lactose concentration and weak negative relationship (r = -0.27, P < 0.001) with quarter yield. Protein concentration had a strong positive correlation (r = 0.62, P < 0.001) with b*. Colostrum b* had a moderate positive relationship (r = 0.53, P < 0.001) with IgG concentration but was moderately negatively correlated (r = -0.48, P < 0.001) with lactose concentration. A weak negative correlation (r = -0.35, P < 0.001) existed between b* and quarter yield. Viscosity score affected (P < 0.001) quarter yield and IgG, protein, lactose, and triglyceride concentrations. Colostrum with viscosity score 1 had the greatest (P < 0.001) quarter yield, and colostrum with viscosity score 2 had a greater (P £ 0.04) yield than that with viscosity score 4 or 5. Colostrum IgG and protein concentrations were greater (P £ 0.005) with increasing viscosity score, but lactose concentrations were less (P £ 0.04) with increasing viscosity score. Triglyceride concentration was greater (P £ 0.02) for viscosity score 4 than for 2 and 3, as well as greater (P < 0.001) for 2 and 3 compared with 1. Overall, colostrum yield and lactose concentration decreased, but IgG and protein concentrations increased, with greater redness (high a*), and yellowness (high b*). Thicker, more viscous colostrum had lower yield and lactose concentration, but greater IgG, protein, and triglyceride concentrations. These data support our hypothesis, suggesting that objective color and subjective viscosity scores are useful in evaluating beef colostrum.