Impact of a phytogenic feed additive on growth performance, feed intake and carcass traits of beef steers


Yang, W.Z., Lima, P., Ramirez, S., Schwandt, E., McAllister, T.A. 2023.Impact of a phytogenic feed additive on growth performance, feed intake and carcass traits of beef steers. Applied Animal Science. in press.

Plain language summary

Phytogenic compounds (PFA) are a group of natural and non-antibiotic growth promoters used as feed additives, derived from herbs, spices or other plants. Supplementation of animal diets with these compounds has been reported to confer antimicrobial, antioxidant, anti-inflammatory, and anti-stress properties. The hypotheses of this study was that the inclusion of a commercial phytogenic compound in growing and finishing feedlot cattle diets would result in similar or improved overall feedlot performance and carcass characteristics when compared with monensin. The objective was to evaluate the effect of PFA on feed intake, growth performance, carcass traits, incidence of liver abscesses, and blood metabolites of growing and finishing cattle. Results from this study that growing steers fed PFA had similar dry matter intake and average daily gain, but lesser gain to feed ratio than monensin. Supplementation of a finishing diet with PFA resulted in growth performance, feed to gain ratio, carcass traits and liver abscess responses that were similar to control and monensin treatments. The results indicate that PFAs can result in some responses that are similar to current antimicrobials such as monensin and further refinement of formulations will be required.


Objective: This study examined the effects of a commercial phytogenic feed additive (PFA) on growth performance, feed efficiency, carcass traits, liver abscesses and the immune response of growing and finishing steers.

Materials and Methods: Forty-five crossbred Angus steers (initial BW; 272 ± 20.5 kg) 22 housed in individual pens (4.9 × 1.8 m) were used in a randomized complete block design in a 23 110-d growing and 120-d finishing experiment. Steers were blocked by BW and allocated to 1 24 of 3 treatments: control (without PFA and monensin), PFA at 500 mg/steer daily, or 25 monensin at 300 mg/steer daily. Steers were fed a total mixed ration ad libitum once daily, 26 and weighed on d 32, 59, 110 in growing, and at beginning and the end of finishing phase.

Results and Discussion: In growing steers, DMI did not differ, whereas final BW (415 vs. 28 403 kg) and average daily gain (ADG, 1.31 vs. 1.20 kg/d) were numerically greater with PFA than control, but did not differ from monensin (BW, 422 kg and ADG, 1.38 kg/d). Gain:feed (G:F) was greater with monensin (0.173) than PFA (0.161) and control (0.156). During finishing, ADG, G:F and carcass traits did not differ, whereas DMI and acute proteins were lesser with monensin than PFA and control.

Implications and Applications: Growing steers fed PFA had similar DMI and ADG, but lesser G:F than monensin. Carcass traits and liver abscesses of finishing steers did not differ among treatments. Feed efficiency of growing steers was not improved by PFA to the same level as monensin. Both PFA and monensin resulted in similar finishing growth performance and G:F during in finishing phase.

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