TY - JOUR AU - Gonzáles Blanco, Jose Pablo AU - Rodolfo WingChing-Jones, Rodolfo PY - 2016/10/12 Y2 - 2024/03/29 TI - Milk Urea Nitrogen relationship with reproductive and productive parameters in Holstein, Jersey and their crosses JF - UNED Research Journal JA - URJ VL - 8 IS - 2 SE - Articles DO - 10.22458/urj.v8i2.1558 UR - https://revistas.uned.ac.cr/index.php/cuadernos/article/view/1558 SP - 175-183 AB - <span>Milk Urea Nitrogen</span><span class="char-style-override-3"> (</span><span>MUN) concentration of 554 Holstein cows, 474 Jersey cows and 454 HxJ crossed cows were determined and related to the days of lactation, daily milk production, days open and calving interval. A milk sample of 100 ml was taken and analyzed by an enzyme urease kit. The Jersey breed exceeded Holstein in 2.49 and HxJ in 3.82 mg/dl. No differences in the MUN content were determined as the days of milk production. Animals with daily production below 40 liters of milk had a MUN 1.84 mg/dl lower than animals with production over 40 liters (18.17 mg/dl). MUN value did not vary according to open days, however, animals with over 360 days in interval calving showed a MUN average of 16.91 mg/dl, which exceeds 1 mg/dl animals presenting values below 360 days interval calving. Holstein and Jersey cows are more likely to have a higher MUN than HxJ crosses. It is necessary to increase the analysis of data from production systems with different management and feeding methods to generate a diagnostic tool that can be applied in dairy production systems in Costa Rica.</span> ER -