Effect of Dietary Inclusion of Fertilized and Unfertilized Sericea Lespedeza Hay on Performance and Plasma Metabolome of Naturally Infected Goats

Abstract This study was conducted to evaluate the effect of the dietary inclusion of unfertilized (AS) and fertilized (AR) sericea lespedeza (Lespedeza cuneata) hay on body weight (BW), average daily gain, and plasma metabolome of goats. Thirty-six naturally parasite-infected (>5000 eggs/gram) 9-month-old intact male Spanish goats (23.9 ± 0.15 kg) were randomly allocated (12 goats per treatment) into three dietary treatments: a) Control (bermudagrass hay), b) AS (unfertilized lespedeza), and c) AR (fertilized lespedeza) for a 60-day pen feeding trial. All treatments were supplemented with a commercial concentrate following a 70:30 forage:concentrate ratio. Feed samples, blood samples, and BW were collected and recorded weekly to estimate chemical composition, initial and final BW, and average daily gain (ADG). Metabolome analysis of the plasma samples was performed using a chemical isotope labelling/liquid chromatography-mass spectrometry-based technique. Pathway enrichment analysis and analysis of the differentially abundant metabolites were performed using MetaboAnalyst 5.0 software. All other data were analyzed following the GLIMMIX procedure (repeated measures) of SAS, with the fixed effect of treatment, week, and the random effect of animals. Chemical composition revealed greater (P ≤ 0.05) CP (15.6 vs. 12%) and NDF (50 vs. 40.8%) in AR hay compared with AS hay. Compared with the control, dietary AR increased (P < 0.05) final BW (30.1 vs. 27.3 kg) and ADG (130.2 vs. 84.5 g/d) in parasite-infected goats. Compared with the control, nitrogen metabolism was enriched (P ≤ 0.05) in AR and AS goats. Compared with AR, the lysine degradation pathway was enriched in AS (P = 7.51 x 10-6) animals. Moreover, the relative concentration of β-leucine was greater (P < 0.05) in goats on the AR diet compared with the control. Results from this research suggest that both AS and AR sericea lespedeza increased nitrogen metabolism in parasite-infected goats. However, dietary AR hay reduced lysine degradation or increased plasma β-leucine concentration compared with AS and the control, respectively. In conclusion, dietary AR lespedeza hay improved the growth performance of parasite-infected meat goats by preventing amino acid degradation and increasing leucine availability, which may help promote muscle regeneration.