Natural 15N abundances in plasma and urea-N concentration in milk as biomarkers of urinary N excretion in dairy cows: a meta-analysis

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Nasrollahi, Sayyed Mahmoud | Noziere, Pierre | Dewhurst, Richard J. | Chantelauze, Céline | Cheng, Long | Froidmont, Eric | Martin, Cécile | Cantalapiedra-Hijar, Gonzalo

Edité par CCSD -

Knowledge on the flux of nitrogen (N) excreted through urines is essential in animal nutritionsince it may provide information on animal N metabolism and the extent of environmental Npollution. Both the 15N natural enrichment of animal proteins over the diet (Δ15Nanimal-diet) and themilk urea N (MUN) concentration have been previously linked to N partitioning. The objective ofthis meta-analysis was to test the effect of combination of Δ15Nanimal-diet in plasma and MUN forpredicting the urinary N excretion (UNE) in dairy cows. Individual data on Δ15Nanimal-diet in plasma,MUN, and UNE of 177 cow/period observations were evaluated by meta-analysis. Data wereanalyzed by mixed-model regression analysis. When model was fitted with either Δ15Nanimal-diet orMUN, both biomarkers were capable to independently predict UNE. However, when Δ15Nanimal-dietand MUN were combined in one model, both biomarkers remained significant and the error ofthe model decreased. In conclusion, both Δ15Nanimal-diet and MUN can predict UNE and theircombination can strengthen the prediction capacity of the model.

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