The Supplementation with a Flavonoid Extract from Citrus Aurantium Reduces Concentrate Intake and Improves Rumen Health Parameters in Holstein Bulls Fed High-Concentrate Diets When Fed in a Single-Space Feeder.

This study evaluated the effects of a flavonoid extract from Citrus aurantium (Bioflavex® CA, 24% naringin) on eating pattern, performance, carcass quality, and rumen wall health of Holstein bulls fed with a single feeder. Ninety-nine bulls (195.2 ± 0.64 kg BW and 149 ± 0.22 d of age) were randomly allocated to one of 6 pens and assigned to control (C) or Bioflavex® CA (BF, 0.4 kg of Bioflavex® CA per ton of concentrate), study was repeated twice. Each pen had one drinker, one separate straw feeder, and one single-space feeder with lateral protections where concentrate (45% corn, 21% corn gluten feed, 11% barley, 11% wheat, 14% CP, 3.32 Mcal of ME/kg; DM basis) was offered. Concentrate intake was recorded daily and BW every 14 d. Animals were slaughtered after 168 d of study (12 periods of 14 d), HCW and carcass quality were recorded, and rumen wall was examined. Data were analyzed using a mixed-effects model with repeated measures and categorical data with a Chi-Square. Concentrate intake was greater (P < 0.05) in C (6.85 ± 0.065 kg/d) than in BF (6.65 ± 0.065 kg/d) bulls; however, ADG (1.64 ± 0.032 kg/d), and concentrate efficiency (0.24 ± 0.022 kg/kg) were not affected by treatments. Final BW tended to be greater (P = 0.06) in C (489.7 ± 3.98 kg) than in BF (479.3 ± 3.98 kg) bulls, but this tendency was not detected for carcass weight (256.1 ± 2.31 kg). No differences between treatments in mean eating pattern parameters were observed; this may be attributed to the great animal variability. During finishing phase (periods 9 to 12), the percentage of meal size data above 750 g was greater (P < 0.05) in C (57.3%) compared with BF bulls (49.3%). Thus, BF reduced large meal sizes and the number of feeder visits numerically increased (in BF meal size explained 74% of the feeder visit variation, P < 0.01). Color of rumen wall tended (P = 0.06) to be lighter for BF bulls (1.27% were “5”, scale from “1” to “5”, with “5” being the darkest) compared with C (9.76% were “5”). In the rumen, baldness areas were lesser (P < 0.01) in BF (48.1%) than in C (67.1%). In conclusion, bulls fed with a single-space feeder supplemented with Bioflavex® CA have a reduced feed intake and large meal sizes, these results may be related with an improvement in rumen health.