Supplementation of urea to a basal pasture diet fed to dairy cows to model N-partitioning relationships

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dc.citation.issue1
dc.citation.volume2
dc.contributor.authorHendriks SJ
dc.contributor.authorLopez-Villalobos N
dc.contributor.authorSheahan AJ
dc.contributor.authorDonaghy DJ
dc.contributor.authorRoche JR
dc.coverage.spatialUnited States
dc.date.accessioned2024-01-28T20:41:16Z
dc.date.accessioned2024-07-25T06:47:16Z
dc.date.available2020-12-11
dc.date.available2024-01-28T20:41:16Z
dc.date.available2024-07-25T06:47:16Z
dc.date.issued2021-01-01
dc.description.abstractThe main objective of this study was to investigate whether altering dietary crude protein (CP) through the supplementation of urea to a basal pasture diet fed to dairy cows accurately modeled N-partitioning relationships. To test this, we first needed to establish safe tolerance levels for urea in this setting. Fifteen multiparous, rumen-fistulated, mid-lactation Holstein-Friesian dairy cows were offered spring pasture (~20 kg of dry matter/cow per day) and allocated to 1 of 3 urea supplementation treatments: low N [0 g/d urea; 21% total dietary CP of dry matter (DM)], medium N (350 g/d urea; 26% total dietary CP of DM), or high N (690 g/d urea; 31% total dietary CP of DM), in a completely randomized design. The amount of urea provided daily increased gradually for all cows over a 21-d period, with target urea supplementation reached by d 21. Milk yield decreased linearly at a rate of 2.35 kg/100 g of urea intake when urea supplementation exceeded 350 g/d for 4 d (~2% of DM intake). Cows from the low- and medium-N treatments subsequently entered metabolism stalls from d 25 to 31 to collect urine, feces, and milk for total N collection. Estimated urinary N output (g/d) increased linearly with N intake (g/d), and the slope of the relationship (slope = 0.86; R2 = 0.82) was consistent with international published results. Because of the consistency of our results with previously documented relationships, our findings indicate that supplementation of urea to a basal pasture diet is a suitable technique for modeling different N intakes from pasture diets to evaluate urinary N mitigation strategies. Urea supplementation, however, should not exceed ~2% of DM intake.
dc.description.confidentialfalse
dc.format.pagination21-26
dc.identifier.author-urlhttps://www.ncbi.nlm.nih.gov/pubmed/36337291
dc.identifier.citationHendriks SJ, Lopez-Villalobos N, Sheahan AJ, Donaghy DJ, Roche JR. (2021). Supplementation of urea to a basal pasture diet fed to dairy cows to model N-partitioning relationships.. JDS Commun. 2. 1. (pp. 21-26).
dc.identifier.doi10.3168/jdsc.2020-0016
dc.identifier.eissn2666-9102
dc.identifier.elements-typejournal-article
dc.identifier.issn2666-9102
dc.identifier.piiS2666-9102(20)30042-9
dc.identifier.urihttps://mro.massey.ac.nz/handle/10179/70872
dc.languageeng
dc.publisherElsevier Inc. and Fass Inc. on behalf of the American Dairy Science Association
dc.relation.isPartOfJDS Commun
dc.rights(c) 2021 The Author/s
dc.rightsCC BY 4.0
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.titleSupplementation of urea to a basal pasture diet fed to dairy cows to model N-partitioning relationships
dc.typeJournal article
pubs.elements-id442453
pubs.organisational-groupOther
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