Effect of supplementation of a commercial mix of plant extract rich in flavonoids on rumen fermentation and meat quality in young Friesian bulls consuming high levels of concentrate

The assay was designed to study the effect of a commercial blend of plant extracts rich in flavonoids (Bioflavex® (g/kg) 200 Naringine and 400 Citrus aurantium extract) supplementation on rumen fermentation (experiment 1) and on meat quality (experiment 2) in Friesian bulls fed high concentrate diets. Experiment 1: 8 cannulated Friesian bulls fed high concentrate diets were used. The animals were randomly assigned to two dietary treatments (4 animals/treatment), a basal concentrate (CTR) or the basal concentrate supplemented with the blend in a 2×4 cross-over design. The experiment, (24 days), was divided into 2 sub-periods (12 days), 10 for dietary changeover followed by 2 days of measurements. Animals supplemented with flavonoids showed a high rumen pH and a low NH3, although no significant differences were observed nor in the concentration neither the proportion of VFA. Experiment 2: 32 young Friesian bulls, 10 months old at the beginning of the trial were used in a complete randomized design to study the effects of Bioflavex® supplementation on performance, carcass characteristics and meat quality of bulls fed high concentrate diets. The experimental diets consisted in the basal concentrate, without (CTR) or supplemented with three levels of a commercial mixture of flavonoids. Pen concentrate and straw consumptions were recorded weekly. All animals were individually weighed, -7d, 0d and 21d of the experimental period and after 21 days when they reached the target slaughter weight the trial was ended. Carcass characteristics, pHu, and subcutaneous fat colour were measured after slaughtering. Different samples were taken then from m. longissimus thoracis, placed in a polystyrene tray and wrapped with an oxygen permeable film to measure the effect of Bioflavex® on the colour stability of meat over 14 days of refrigerated storage in a fridge. Additional meat samples were X taken from m. longissimus thoracis and packed in a high oxygen modified atmosphere or overwrapped with an oxygen permeable film, and subjected to simulated retail display conditions at constant temperature (4ºC), under light for 12 hours per day to measure lipid oxidation, colour and willingness of purchasing the meat over 14 days of display. No differences in any of the productive parameters such as average daily gain, slaughter weight, dressing percentage, carcass weight and classification scores were detected. pHu and subcutaneous fat colour were placed in the normal range for this type of animals and sex and they were not altered by the presence of flavonoids. Nevertheless, the anti-oxidative effect of flavonoids particularly in steaks which had the highest level of antioxidants (FL3), was evidenced in the colour of meat packed in film and kept in dark or under retail display conditions, improving the red index stability and inhibiting the increase in Hue that took place on the steaks after fourteen days of display in the control lot. No significant differences were observed in the steaks stored in MAP due to the higher oxygen content of the atmosphere which was able to maintain the bright red colour. Lipid stability was not significantly improved as a result of supplementation with Bioflavex®. However, meat from FL3 stored in film showed the lowest TBARS values and were lower than the limit value of perception of rancidity. The consumer acceptability of meat stored in film was not affected by the inclusion of Bioflavex® during retail display. FL3 had the highest values of consumer acceptability; however, the values of willingness to purchase were too low to be considered acceptable at retail levels. In the meat stored in MAP, there were not differences between treatments at short-term of display time. However, the FL3 had the highest acceptability compared with CTR at long-term of display.