Efecto del uso de extracto de levaduras o aceites esenciales en sustitución de la monensina en dietas de novillos en engorde sobre la performance a corral y a la faena

The objective of this study was to evaluate the effect of using yeast or essential oils as substitutes for sodium monensin in finishing diets on the performance, carcass characteristics, and meat quality of feedlot cattle.

Forty-eight Hereford steers, (401 ± 25 kg) were randomly assigned to 12 groups, which were then allocated to one of the three experimental diets. 1) Control (MON): fed completely mixed ration (RTM) ad libitum + 1.5 grams of sodium monensin at 20%; 2) Yeast (LEV): fed with the same RTM ad libitum + 3.0 grams of CELMANAX (company), a commercial product combining yeast culture, yeast extract, and hydrolyzed yeast; 3) Essential Oils (AE): fed with the same RTM ad libitum + 0.3 grams of a source of essential oils, XTRACT Rumiant (company); composed by a mixture of 9.4% eugenol (clove extract), 5.4% cinnamaldehyde (cinnamon extract), and 3.5% capsicum oil (chili extract). Each treatment consisted of 4 repetitions, with each repetition comprising 4 steers fed in the same pen.

The variables studied during the feeding period included dry matter intake (DMI), feed conversion efficiency (FCR), average daily gain (ADG), and behavioral activity. Subsequently, variables on carcass and meat characteristic were studied after slaughter. No statistically significant differences were found among the treatment groups in any of the animal performance variables, such as DMI (MON: 14.09, LEV: 14.43, AE: 14.93, P>0.05), FCR (MON: 6.20, LEV: 6.48, AE: 6.45, P>0.05), or ADG (MON: 2.50, LEV: 2.24, AE: 2.41, P>0.05). Regarding behavioral variables, differences were observed in feeding activity (MON: 0.11, LEV: 0.14, AE: 0.16, P<0.05) and rumination (MON: 0.04, LEV: 0.10, AE: 0.07, P<0.05). Differences were found in backfat thickness (MON: 15.25, LEV: 12.00, AE: 11.25, P<0.05) and muscle color luminosity (MON: 38.88, LEV: 39.03, AE: 41.15, P<0.05). Nonetheless, no differences were detected in marbling (MON: 203.5, LEV: 187.5, AE: 175.0, P>0.05) and pH (MON: 5.51, LEV: 5.48, AE: 5.48, P>0.05). These results suggests that both yeast and essential oils have the potential to replace sodium monensin as a nutritional additive in finishing diets without affecting the productivity, carcass, and meat quality.