Marshall, CJBeck, MRGarrett, KBarrell, GKAl-Marashdeh, OmarGregorini, Pablo2021-09-082021-08-222021-082021-08-202076-2615UF7BK (isidoc)34438921 (pubmed)https://hdl.handle.net/10182/14190Inefficient nitrogen (N) use from pastoral dairy production systems has resulted in environmental degradation, as a result of excessive concentrations of urinary N excretion leaching into waterways and N₂O emissions from urination events into the atmosphere. The objectives of this study were to measure and evaluate the total N balance of lactating dairy cows selected for milk urea N concentration breeding values (MUNBVs) consuming either a 100% perennial ryegrass (Lolium perenne L.) or 100% plantain (Plantago lanceolata L.) diet. Sixteen multiparous lactating HolsteinFriesian × Jersey cows divergent for MUNBV were housed in metabolism crates for 72 h, where intake and excretions were collected and measured. No effect of MUNBV was detected for total N excretion; however, different excretion characteristics were detected, per urination event. Low MUNBV cows had a 28% reduction in the concentration of urinary urea nitrogen (g/event) compared to high MUNBV cows when consuming a ryegrass diet. Cows consuming plantain regardless of their MUNBV value had a 62% and 48% reduction in urinary urea nitrogen (g/event) compared to high and low MUNBV cows consuming ryegrass, respectively. Cows consuming plantain also partitioned more N into faeces. These results suggest that breeding for low MUNBV cows on ryegrass diets and the use of a plantain diet will reduce urinary urea nitrogen loading rates and therefore estimated nitrate leaching values, thus reducing the environmental impact of pastoral dairy production systems.18 pagesElectronicen© 2021 by the authors. Licensee MDPI, Basel, Switzerland.dairy cowsenvironmental impactN excretionplantainryegrassJournal Article10.3390/ani110824642076-2615ANZSRC::300302 Animal managementANZSRC::300303 Animal nutritionANZSRC::300307 Environmental studies in animal productionANZSRC::300204 Agricultural management of nutrientsANZSRC::300210 Sustainable agricultural developmentANZSRC::3003 Animal productionANZSRC::3009 Veterinary sciencesANZSRC::3109 Zoologyhttps://creativecommons.org/licenses/by/4.0/Attribution