1491 Associations between residual feed intake and metabolite profiles and feeding behavior traits in feedlot cattle

Abstract

Objectives of this study were to evaluate the effects of residual feed intake (RFI) classification on performance and feed efficiency in steers fed a high-grain diet and to examine associations between RFI and blood metabolite profiles and feeding behavior traits to identify RFI biomarkers. Performance, DMI, and feeding behavior traits were measured for 70 d in Angus crossbred steers (N = 168) using a GrowSafe system. Steers were classified into low- (n = 52), medium- (n = 64), and high- (n = 52) RFI groups based on ±0.5 SD from the mean RFI of 0.00 (SD = 0.82). Low-RFI steers consumed 17% less (P < 0.0001) DMI (9.05 vs. 10.89 ± 0.14 kg/d), had 18% lesser (P < 0.0001) feed:gain ratio (5.05 vs. 6.11 ± 0.10), and generated $95 per head more (P < 0.001) profit compared with high-RFI steers, even though ADG and carcass value were not affected by RFI classification. Blood samples were collected from steers with lowest RFI (n = 25) and highest RFI (n = 24) on Day 70 of the trial, and serum metabolite concentrations were analyzed using 1H-NMR spectroscopy. Partial least squares (PLS; MetaboAnalyst) were used to examine associations between RFI and metabolites and feeding behavior traits. Of the 12 feeding behavior traits evaluated, 4 traits had variable of importance in projection (VIP) scores > 1.0, which included head-down (HD) duration, bunk visit (BV) duration, nonfeeding interval (NFI) duration, and head-down–to–meal duration ratio (HD:MD). The first 2 components of PLS accounted for 54% of between-animal variance in RFI. Steers with low RFI had longer (P < 0.001) NFI duration (less time at the bunk), 45% lower HD duration, 35% lower BV duration, and 32% lower HD:MD than high-RFI steers. Of the 44 metabolites detected by 1H-NMR, 5 metabolites had VIP scores > 2, which included glycine, betaine, tyrosine, valine, and leucine. The first 2 components of PLS accounted for 34% of between-animal variance in RFI. Steers with low RFI had higher (P < 0.001) concentrations of glycine and lower (P < 0.06) concentrations of betaine, tyrosine, valine, and leucine than high-RFI steers. These preliminary results reveal that metabolomic profiling and feeding behavior traits may provide opportunities to identify biomarkers that are predictive of RFI in beef cattle.