Impact of presence of zeolite in diets for lambs supplemented with zilpaterol hydrochloride: Growth performance and dietary energetics

Zeolite (ZEO) and zilpaterol hydrochloride (ZH) are feed additives commonly included at the same time in lamb's diets, but there is no information regarding the potential antagonism between both on growth performance and dietary energy, for this reason, 48 Pelibuey x Katahdin male intact lambs (36.2 +/- 4.4 kg initial live weight) were assigned to the following treatments: 1) Basal diet without ZEO and ZH (CON); 2) inclusion of 3% ZEO replacing cracked corn (Zea mays L.) and soybean meal (Glycine max. (L.) Merr.) in the CON diet (ZEO), 3) CON diet supplemented with 6 mg ZH kg(-1) diet (ZH), and 4) ZEO diet supplemented with 6 mg ZH kg(-1) diet (ZEO+ZH). The experimental period was 34 d. There were no treatment interactions (P >= 0.21). The ZEO inclusion diluted the diet net energy (NE) by 2.9%, but compared to CON, DM intake (DMI), average daily weight gain (ADG), and gain-to-feed ratio (GF) were not affected. Therefore, ZEO increased (P < 0.01) the observed-to-expected diet NE by 3.9%. Compared to CON and ZEO lambs, ZH lambs showed greater (P < 0.01) ADG (12.1%) GF (11.5%), and dietary NE (7.3%) values. As in the non -supplemented ZH diets, the presence of ZEO in the ZH diet increased (P < 0.05) the observed-to-expected dietary NE by 4.6% compared to the diet with ZH alone. Based on the results, ZEO similarly affects diet NE in lambs when included in the diet alone or with ZH. Further, ZEO is not an antagonist to ZH, and the energy dilution due to ZEO inclusion did not affect the benefits of ZH supplementation.