Plasma proteins δ15N vs plasma urea as candidate biomarkers of between-animal variations of feed efficiency in beef cattle: Phenotypic and genetic evaluation

Identifying cattle with superior growth feed efficiency through their natural 15 N abundance and plasma urea concentration: a meta-analysis.

“…However, our results were obtained from more diverse cattle production systems across Europe, using different diets and breeds, which reinforces its potential to be applied in commercial farms. In addition, because our 15 N natural abundance in animal proteins were corrected by the isotopic signatures of the corresponding diets, unlike in our previous study (Guarnido-Lopez et al, 2021), we proved that Δ 15 Nanimal-diet may also reflect the FCE changes promoted by diets and thus serving to compare farms with different production conditions or to rank different dietary strategies in terms of FCE.…”

“…In this regard, a new biomarker of NUE in ruminants has been confirmed by metaanalysis (Cantalapiedra-Hijar et al, 2018a) with the potential to identify differences betweenanimals in feed efficiency (Guarnido-Lopez et al, 2021). This biomarker is based on the N isotopic discrimination naturally occurring between the animal and its diet (Δ 15 Nanimal-diet, for details see Cantalapiedra-Hijar et al, 2016) and can reveal changes in N partitioning in many different animal species (Gaye-Siessegger et al, 2004;Sears et al, 2009), as well as in humans (Fuller et al, 2004).…”

“…The superior ability of Δ 15 Nanimal-diet vs plasma urea concentration to identify betweenanimal variability in feed efficiency (FCE and RFI) has been extensively discussed by Guarnido-Lopez et al (2021). Advantages of Δ 15 Nanimal-diet vs plasma urea would include the stability in daily values irrespective of the sampling time (i.e.…”

“…nitrogen retention/N intake) are biologically linked in growing ruminants considering feed sorting is negligible with most fattening diets and that body weight gain and protein accretion are traits highly correlated (Geay, 1984). Indeed, recent studies highlighted that plasma biomarkers of N partitioning and NUE may also serve to track between-animal variability in feed efficiency in fattening young bulls fed contrasting diets (Cantalapiedra-Hijar et al, 2020;Jorge-Smeding et al, 2021;Guarnido-Lopez et al, 2021). This means that biomarkers predicting differences in NUE could equally work for discriminating individuals in terms of feed efficiency.…”

“…However, the few studies attempting to correlate Δ 15 Nanimal-diet to residual feed intake failed to prove significant relationships (Wheadon et al, 2014;Meale et al, 2017). Although we have recently validated the 15 N natural abundance in plasma as a biomarker of feed efficiency variation in Charolais young bulls from the same contemporary group (Guarnido-Lopez et al, 2021), the generalization of the relationship between Δ 15 Nanimal-diet and feed efficiency across different experimental conditions (diets and breeds) has not yet been explored.…”