Effects of Including a Novel High-Anthocyanin Corn Cob Meal in a High-Roughage Diet on Performance and Gas Flux of Beef Cattle

Abstract Methane (CH4) is a greenhouse gas emitted by cattle that is produced as a byproduct of ruminal fermentation. Dietary inclusion of anthocyanins has previously decreased in vitro CH4 production from both high- and low-roughage diets. Anthocyanins potentially sequester hydrogen in the rumen which may limit CH4 production from methanogenic bacteria. As such, feeding anthocyanins represents a promising CH4 mitigation strategy. Thus, the objective of this preliminary experiment was to determine the effects of replacing conventional [CONV; 0.04 mg anthocyanin×g-1 of dry matter (DM)] corn cob meal (CCM) with a novel high-anthocyanin (Hi-A) CCM [TAMZ101 corn hybrid (4.99 mg anthocyanin×g-1 DM; Texas A&M AgriLife Research; Lubbock, TX)] in a high-roughage (40% DM) diet on growth performance and gas flux of beef cattle. Steers (n =14; average initial body weight = 286 kg ± 17 kg) were trained to individual Calan bunks and randomly assigned to dietary treatments on d 0 using a completely randomized design, where 20% of total diet DM was either Hi-A or CONV CCM. The trial consisted of a 63-d feeding period in which carbon dioxide (CO2) emission, CH4 emission, and oxygen (O2) consumption (g×animal×d-1) were measured using a GreenFeed system (C-Lock Inc.; Rapid City, SD). Statistical analyses were conducted using JMP Pro v.16 (SAS Institute Inc.; Cary, NC) where individual animal served as the experimental unit and treatment was a fixed effect. Cook’s distance values were used to identify and remove outliers for each individual response variable. Statistical significance was set at P ≤ 0.05 with a tendency toward significance defined as 0.05 < P ≤ 0.10. Due to insufficient statistical power, 10.2% and 5.7% numeric increases were statistically undetectable in total dry matter intake (DMI; P = 0.13; 1-ß = 0.31) and average daily gain (ADG; P = 0.19; 1-ß = 0.25) when CONV CCM was replaced with Hi-A CCM. Similarly, marginal numeric differences in feed efficiency, CO2 emission, daily CH4 emission, and O2 consumption were statistically undetectable across treatments (P ≥ 0.18; 1-ß ≤ 0.22). Numeric differences in DMI of steers fed Hi-A CCM contributed to a 7.5% decrease (P = 0.05; 1-ß = 0.51) in CH4 yield (g CH4×kg DMI-1) when compared with steers fed CONV CCM. Treatment did not affect CH4 emission intensity (g CH4×kg ADG-1; P = 0.26; 1-ß = 0.19). Results from this preliminary experiment and a previous in vitro experiment indicate that anthocyanins from Hi-A CCM have CH4 mitigation potential in high-roughage diets. Further research is warranted to determine if anthocyanins are effective at reducing CH4 yield across a range of diet compositions and if anthocyanins from Hi-A CCM can be extracted, condensed, and repackaged into a delivery system that is both economically and logistically feasible.