Intake of non-contaminated and high immunoglobulin content colostrum by neonatal calves is an important factor in successful calf programs. The objectives of this study were to determine the risk factors for the occurrence of diarrhea and pneumonia by evaluating colostrum quality (Ig content determined with colostrometer and refractometry) and bacterial contamination in 300 Holstein calves born in June 2014. A second objective was to describe the effect of feeding colostrum of different quality on growth and physiological parameters in neonatal calves. Calves were removed from their dams shortly after parturition and fed 2.8 L of colostrum by bottle; calves were placed in individual portable roofed pens. Colostrum variables were total bacterial counts, coliform bacteria counts, refractometry values, and Ig content. Multivariable logistic-regression analyses were performed. None of the variables included in the model affected the occurrence of diarrhea. The calves with highest odds of pneumonia were those receiving colostrum with total standard plate counts >15,000/mL (odds ratio = 1.8). Calves fed colostrum with < 15,000 counts/mL (n = 145) had greater weaning weights (66.3 kg ± 6.7 vs. 63.4 kg ± 6.7; P < 0.01) and preweaning daily weight gain (0.515 kg/d ± 116 vs. 0.477 kg/d ± 123; P < 0.01) than calves fed colostrum with >15,000 counts/mL (n = 155). Calves fed colostrum with the highest bacterial counts presented higher (P < 0.01) values for fecal consistency (1.5 ± 0.8) than calves receiving colostrum with low bacterial counts (1.2 ± 0.5; scale 1 to 4, with 1 being normal feces to 4 being severe diarrhea; P < 0.01). Calves receiving colostrum with higher Ig content (>85 mg/mL, measured with colostrometer) presented feces more solid (P < 0.01) than calves receiving colostrum with Ig < 85 mg/mL (1.2 ± 0.6 vs 1.5 ± 0.9). There was no difference between groups when examining the effect of different characteristics of colostrum on height to withers, respiration condition and rectal temperature. Given the conditions of this trial, feeding colostrum with <15,000 total bacterial counts/ml reduced the odds of pneumonia and enhanced growth rate of Holstein calves in a hot environment.