Lay Summary Growth performance and gas flux were evaluated in summer feedlot conditions for Bos indicus (BI) and Bos taurus (BT) steers managed with (TRT) and without (CON) the use of growth-promoting technology (GPT). In the first 84 d of the study, BT had greater dry matter intake (DMI), average daily gain (ADG), feed efficiency (G:F), and final body weight (FBW). Within sub-species, DMI did not differ between TRT and CON during the first 84 d, but ADG, G:F, and FBW were greater for TRT compared to CON. In the last 96 d of the study, observations were similar to the first 84 d, but DMI was greater with the use of GPT, and the magnitude of difference in DMI as a percentage of body weight, ADG, G:F, and FBW differed by sub-species between treatments. Less desirable quality grades were observed in BI compared to BT. Furthermore, BI steers emitted less methane (CH4), whether expressed as daily emissions or per kg of DMI. However, the use of GPT resulted in a decrease in methane emitted per kg of ADG and carcass gain. This study observed that BT steers exhibited greater growth performance and carcass quality, but BI steers emitted less total methane.
Schilling-Hazlett et al. (Wed,) studied this question.