Effects of Flavonoids Extracted from Citrus aurantium on Performance, Behavior, and Rumen Gene Expression in Holstein Bulls Fed with High-Concentrate Diets in Pellet Form

Abstract

Flavonoid supplementation may modify the behavior and rumen inflammatory response of fattening bulls, and this could be related to the concentrate presentation (mash or pellet) form. In the present study, 150 Holstein bulls (183.0 ± 7.53 kg BW and 137 ± 1.8 d of age) were randomly allocated to one of eight pens and assigned to control (C) or (BF) (Citrus aurantium, Bioflavex CA, HealthTech Bio Actives, Spain, 0.4 kg per ton of concentrate of Bioflavex CA, 20% naringin). Concentrate (pellet) intake was recorded daily, and BW and animal behavior fortnightly. Animals were slaughtered after 168 d of study, and ruminal epithelium samples were collected for gene expression analyses. Treatment did not affect animal performance; however, BF supplementation reduced agonistic interactions and oral non-nutritive behaviors and increased the time devoted to eating concentrate and ruminating activity (p < 0.05). The gene expression of some genes in the rumen epithelium was greater or tended to be greater in BF than C bulls (bitter taste receptor 16, cytokine IL-25, β-defensin; p < 0.10; pancreatic polypeptide receptor 1 and tumor necrosis factor alpha; p < 0.05). In conclusion, flavonoid supplementation modifies the expression of genes in the rumen epithelium that could be related to inflammation and animal behavior modulation.

Keywords: behavior; bitter taste receptors; bulls; flavonoids; rumen inflammation.

Figure 1

Mean of the concentrate intake during the growing and finishing phases of Holstein bulls fed high-concentrate diets with or without citrus flavonoids supplementation (* = p < 0.05).

Figure 2

Flehmen every 15 min during the growing and finishing phase of Holstein bulls fed high-concentrate diets with or without citrus flavonoids supplementation (* = p < 0.05).

Figure 3

Gene expression in rumen epithelium of Holstein bulls fed high-concentrate diets with or without citrus flavonoids supplementation (* = p < 0.05 and t = 0.05 ≤ p ≤ 0.10). TAS2R7: Bitter taste receptor 7; TAS2R16: Bitter taste receptor 16; TAS2R38: Bitter taste receptor 38; TAS2R39: Bitter taste receptor 39; FFAR2: Free fatty acid receptor 3 (gpr41); FFAR3: Free fatty acid receptor 2 (gpr43); ADRA2C: Alpha 2-adrenergic receptors subtype C; PPYR1: Pancreatic polypeptide receptor 1; CCKBR: Cholecystokinin receptor 4; IL-25: Interleukin-25; TLR4: Pattern recognition receptors, like Toll-like receptor 4; TNFa: Tumor necrosis factor alpha; B-Def: Beta-defensin. The values presented herein correspond to back-transformed means; however, SEM corresponds to the ANOVA analyses using log-transformed data.