TY - JOUR
T1 - The effects of degradable nitrogen level and slow release urea on nitrogen balance and urea kinetics in Holstein steers
AU - Holder, V. B.
AU - Tricarico, J. M.
AU - Kim, D. H.
AU - Kristensen, N. B.
AU - Harmon, D. L.
N1 - Publisher Copyright:
© 2014 Elsevier B.V.
PY - 2015
Y1 - 2015
N2 - The objective of this study was to compare nitrogen metabolism and urea kinetics between diets containing either rapidly degrading or slow degrading non-protein nitrogen (NPN) at varying levels of degradable intake protein (DIP). Treatments were slow release urea (Optigen®, Alltech, Inc.) fed at 1.01 and 1.14 and feed grade urea (UREA) fed at 0.89 and 1.00 of calculated DIP requirements. Eight Holstein steers (209 ±15kg) implanted with 28mg estradiol+200mg trenbolone acetate (Synovex Plus, Fort Dodge Animal Health, Fort Dodge, IA) were used in a replicated 4×4 Latin square. Experimental periods were 27 days, with 19 day adaptation followed by 7 day of urine and fecal collection and 1 day of blood sampling. Continuous (78h) intravenous infusion of 15N15N-urea allowed the estimation of systemic urea kinetics. Dry matter intake was not different between treatments (7.2kg/day). Increasing DIP had a tendency to increase dry matter digestibility (DMD) for both Urea and Optigen®. Urea had higher DMD than Optigen®. Increasing DIP increased urinary N output for both UREA and Optigen®, and increased N-retention at 1.14 Optigen®. Increasing DIP increased urea-N entry rate (UER) and urinary urea-N excretion (UUE) for both Optigen® and UREA. Gastrointestinal entry of urea-N, urea-N lost to feces and urea-N apparently used for anabolism were not different between treatments. Plasma urea concentration was greater in higher DIP diets and higher for Urea than Optigen® at 1.00 DIP. Therefore increasing DIP level will increase N-excretion related to higher urea production and excretion in urine but may also increase diet digestibility. Most changes in N metabolism were driven by N intake.
AB - The objective of this study was to compare nitrogen metabolism and urea kinetics between diets containing either rapidly degrading or slow degrading non-protein nitrogen (NPN) at varying levels of degradable intake protein (DIP). Treatments were slow release urea (Optigen®, Alltech, Inc.) fed at 1.01 and 1.14 and feed grade urea (UREA) fed at 0.89 and 1.00 of calculated DIP requirements. Eight Holstein steers (209 ±15kg) implanted with 28mg estradiol+200mg trenbolone acetate (Synovex Plus, Fort Dodge Animal Health, Fort Dodge, IA) were used in a replicated 4×4 Latin square. Experimental periods were 27 days, with 19 day adaptation followed by 7 day of urine and fecal collection and 1 day of blood sampling. Continuous (78h) intravenous infusion of 15N15N-urea allowed the estimation of systemic urea kinetics. Dry matter intake was not different between treatments (7.2kg/day). Increasing DIP had a tendency to increase dry matter digestibility (DMD) for both Urea and Optigen®. Urea had higher DMD than Optigen®. Increasing DIP increased urinary N output for both UREA and Optigen®, and increased N-retention at 1.14 Optigen®. Increasing DIP increased urea-N entry rate (UER) and urinary urea-N excretion (UUE) for both Optigen® and UREA. Gastrointestinal entry of urea-N, urea-N lost to feces and urea-N apparently used for anabolism were not different between treatments. Plasma urea concentration was greater in higher DIP diets and higher for Urea than Optigen® at 1.00 DIP. Therefore increasing DIP level will increase N-excretion related to higher urea production and excretion in urine but may also increase diet digestibility. Most changes in N metabolism were driven by N intake.
KW - Cattle
KW - Nitrogen metabolism
KW - Urea recycling
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U2 - 10.1016/j.anifeedsci.2014.12.009
DO - 10.1016/j.anifeedsci.2014.12.009
M3 - Article
AN - SCOPUS:84922611414
SN - 0377-8401
VL - 200
SP - 57
EP - 65
JO - Animal Feed Science and Technology
JF - Animal Feed Science and Technology
IS - 1
ER -