Abstract
BACKGROUND: Although it has been demonstrated that gastrointestinal microorganisms greatly influence livestock performance, the effect of gastrointestinal microorganisms on the growth performance of crossbred cattle remains unclear. Due to their superior production characteristics, understanding the impact of gastrointestinal microorganisms on the growth performance of crossbred beef cattle is of significant importance for improving farming efficiency. RESULT: In this study, healthy Simmental with similar birth date and weight were selected as dams, Simmental (Combination I), Belgian Blue (Combination II) and Red Angus (Combination III) were used as parents for crossbreeding. The progeny of the three combination crosses were measured for growth performance under identical conditions from birth rearing to 18 months of age (n = 30). Rumen fluid and plasma were collected for macro-genomic and non-targeted metabolomic analysis (n = 8). The results showed that Combination II was superior to Combination I and Combination III in body weight (BW) and body height (BH) (P < 0.05). Mycoplasma, Succinivibrio, Anaerostipes, Methanosphaera, Aspergillus, and Acidomyces were significantly increased in the rumen of Combination II (P < 0.05), whereas differentially expressed metabolites (DEMs) 9,10,13-Trihome (11), 9,12,13-Trihome and 9(10)-Epome, and 9(S)-Hpode were reduced in abundance. In addition, plasma DEM PC (14:0/P-18:1(11Z)), PC (16:0/0:0), and PC (17:0/0:0) were down-regulated in combination II. Correlation analysis revealed that Anaerostipes, Methanosphaera, and Succinivibrio were associated with PC (14:0/P-18:1(11Z)), 9(10)-Epome, 9,10,13-Trihome (11), 9(S)-Hpode, 9,10,13-Trihome, PC (17:0/0:0), and PC (16:0/0:0). Growth traits were significantly positively correlated with the three dominant genera, Anaerostipes, Methanosphaera, and Succinivibrio, while significantly negatively correlated with key rumen metabolites and plasma metabolites (P < 0.05). CONCLUSIONS: Our study reveals the role of rumen microorganisms and its metabolites with host metabolism in the regulation of growth performance of crossbred cattle, which will contribute to the development of modern cattle breeding.