Effects of flavonoids extracted from Citrus aurantium on performance, eating and animal behavior, rumen health, and carcass quality in Holstein bulls fed high-concentrate diets

Abstract

The effects of flavonoids extracted from Citrus aurantium (Bioflavex® CA) on eating pattern, performance, carcass quality, and rumen wall health of Holstein bulls fed on a single feeder were studied. One hundred ninety-eight bulls (195.3 ± 19.6 kg of body weight and 149 ± 6.8 d of age) were used in a complete block randomized design. Groups of animals with the same mean and coefficient of variation of body weight (replicates) were randomly allocated in 1 of 6 pens (20 animals per pen), and each pen was assigned to one of 6 pens and assigned to a Control (C) diet or to a diet supplemented with flavonoids (Bioflavex® CA, Interquim S.L., Spain) (BF, 0.4 kg per ton of concentrate of Bioflavex® CA) in two consecutive fattening cycles. Concentrate intake was recorded daily, and BW fortnightly. Animal behavior was monitored by visual scan procedure every fourteen days. Animals were slaughtered after 168 d of study, hot carcass weight and carcass quality were recorded, and internal rumen wall was examined. Concentrate intake was higher (P < 0.05) in C than in BF bulls; however, ADG and concentrate efficiency were not affected by treatments. The final BW tended (P = 0.06) to be higher in C than in BF bulls, but this difference disappeared for carcass weight. In the finishing phase, the proportion of meal size values above 750 g was higher (P < 0.05) in C compared with BF bulls. Throughout the study exhibited more displacements and fighting than C bulls, whilst C bulls performed more (P < 0.05) oral behaviors. During the finishing phase, sexual behaviors such as flehmen and complete mounts were higher (P < 0.01 and P < 0.05, respectively) in C bulls as well, and C bulls tended (P = 0.10) to perform more attempted mounts compared with BF bulls. In the slaughterhouse, color of rumen wall tended (P = 0.06) to be lighter for BF compared with C bulls, and presence of baldness areas in the rumen was lesser (P = 0.01) in BF animals. In conclusion, when bulls were supplemented with Bioflavex® CA, feed intake was reduced. Flavonoids supplementation increased time eating straw, reduced agonistic behaviors throughout the study and sexual interactions during the finishing phase, potentially improving animal welfare. Rumen wall parameters analyzed were indicative of a better rumen health in BF than in C bulls, which maybe due to the reduction of large meal sizes.