The objective of this study was to determine total immunoglobulin (Ig) concentration in colostrum produced by dairy cows and establish the effect that breed and parity can have on Ig concentration. The data presented correspond to determinations of total Ig concentration determined by a colostrometer in 537 colostrum samples obtained in 50 dairy farms in the provinces of San José, Alajuela, Heredia, and Cartago. Cow breeds were classified into Holstein, Jersey, Holstein × Jersey, and other. Farm size ranged from 10 to 300 milking cows. To determine breed and parity number effect on colostrum Ig concentration, MIXED procedure was used, where dam was considered as a random effect. For the purposes of this study, good quality colostrum was considered when Ig concentration was ≥50 mg/mL. Immunoglobulin concentration ranged from 10 to 140 mg/mL with an average of 85 mg/mL. Of all the samples analyzed, 13.2% had an inadequate concentration of Ig. When considering breed effect on Ig concentration, no significant differences were found (P > 0.05). Parity number significantly (P < 0.05) influenced Ig concentration and it was found that Ig concentration increased with parity number. Based on the current study, Ig concentration was adequate for calf feeding in 87% of colostrum samples. Table 1. Effect of dam breed on total Ig concentration in 537 colostrum samples from 50 dairy farms in Costa Rica

Dam breed	Number	Ig (mg/mL)	SEM
Holstein	270	88.8	1.9
Holstein × Jersey	64	85.9	2.5
Jersey	146	85.5	2.6
Other	57	85.6	4.2