Ingestion of high-quality colostrum has historically been recognized as a critical management factor to transfer passive immunity (TPI). Evidence suggests that colostrum production shows high individual and seasonal variability. Nonetheless, knowledge of individual factors as well as prepartum nutritional and management strategies associated with colostrum production remain limited to date. Thus, the first two objectives of this dissertation were to 1) describe the variability in colostrum production and 2) identify individual cow, herd management, environmental, and nutritional factors associated with colostrum production. Colostrum records from Holstein cows (n = 18,343) on 18 commercial dairy farms were collected in an observational study. Median (quartile 1, quartile 3) colostrum yield and mean (SD) Brix % was 4.0 (2.3, 6.2) kg and 24.6 (3.9)% for primiparous cows and 4.6 (2.7, 7.7) kg and 25.7 (4.4)% for multiparous cows, respectively. Factors such as parity, calf sex, dry period length, and gestation length as well as environmental and nutritional factors were identified as associated with colostrum production. In a second study, the effect of close-up metabolizable protein (MP) supply (1,175 vs. 1,603 g of MP/d) on colostrum production was investigated. Feeding an elevated supply of MP tended to increase colostrum yield in cows entering parity 2 but did not affect the yield from cows entering parity ≥3 or colostral concentrations of IgG, fat, or protein. Further, this dissertation evaluated the agreement of methods used to determine colostrum quality. Objective 3 of this dissertation was to compare turbidimetric immunoassay (TIA) and a Brix refractometer with the gold standard measurement radial immunodiffusion (RID) for the evaluation of colostrum quality. Results showed TIA and Brix % had a strong correlation with RID, but a systematic and proportional bias was observed for TIA compared to RID. Lastly, objective 4 aimed to describe the variability of hemoconcentration in calves during the time of TPI assessment as well as describe the effect of adjusting total protein (TP) for the individual degree of hemoconcentration. The findings identified a sample mean (range) plasma proportion of 68.8 (50.5 to 86.0)% in 696 1 to 9-d of age Holstein calves. Adjustment of TP increased the proportion of calves with poor TPI by 4.4 percentage points. Collectively, this work described variability in colostrum production and hemoconcentration during the time of TPI assessment. Individual, environmental, nutritional, and managerial factors identified in this dissertation provide foundational knowledge to our understanding of variables associated with colostrum production and TPI.