THE VISUAL APPEARANCE AND SOMATIC-CELL COUNT OF MAMMARY SECRETIONS COLLECTED FROM PRIMIGRAVID HEIFERS DURING GESTATION AND EARLY POSTPARTUM

Mammary secretions, obtained before and after calving, were examined f or visual appearance, SCC, and bacteriology as part of a larger study determining the prevalence of IMI in 1588 primigravid heifers. Appeara nce of secretions was categorized into five groups: thin and watery, h oney-like, serumy, milky, or thickened colostrum. Precalving secretion s were further characterized as low viscosity (thin and watery, serumy , or milky) or high viscosity (honey-like and thickened colostrum). Po stcalving secretions were further characterized as normal (milky, thic kened colostrum) or abnormal (thin and watery, serumy, or honey-like). Infected precalving quarters (81%) had low viscosity secretions. Quar ters that were uninfected precalving (75%) had high viscosity secretio ns. Greater than 90% of all postcalving milk samples appeared to be no rmal, regardless of geographic location, season, or bacterial infectio n status. Only 77% of the samples from quarters infected with contagio us and noncontagious mastitis pathogens had normal appearance. Precalv ing SCC from bacteriologically negative quarters were lower than SCC f rom infected quarters. Similarly, postcalving SCC were lower from the bacteriologically negative quarters than from the infected quarters. I nfected quarters had higher mean SCC than the uninfected quarters duri ng both pre- and postcalving periods.