Effect of an algae feed additive on reducing enteric methane emissions from cattle.

Alga 1.0, a product containing bromoform, was fed to cattle to evaluate its effects on methane ( CH 4 ) and carbon dioxide ( CO 2 ) emissions and diet digestibility. Twelve nonlactating, nonpregnant Jersey cows (490 ± 19 kg body weight) were used in four replicated 3 × 3 Latin squares with three periods, each consisting of 21 d. Cows were blocked by feed intake (averaged intakes over 4 wk prior to trial) and assigned randomly to one of three treatments. Treatments included Alga 1.0 fed at 0, 69, and 103 g/d in a 0.454 kg/d dry matter ( DM ) top-dress daily in a modified distillers grains plus solubles ( MDGS ) carrier. Diet consisted of 60% dry-rolled corn, 20% corn silage, 15% modified distillers grains, and 5% supplement (DM basis). Headbox-style indirect calorimeters were utilized to evaluate gas production from individual cows with two nonconsecutive 23-h collections in each period. Data were analyzed using the GLIMMIX procedure of SAS with cow within square as experimental unit and as a random effect, and treatment and period as fixed effects. Linear and quadratic contrasts were used to compare treatments. Feeding Alga 1.0 linearly reduced dry matter intake ( DMI , P  < 0.01) by 10.1% for 69 g/d inclusion and 13.3% for 103 g/d inclusion compared to the control. Nutrient intakes decreased linearly ( P  < 0.01) due to lower DMI, but nutrient digestibility was not impacted ( P  ≥ 0.28). Inclusion of Alga 1.0 did not impact gross energy or digestible energy concentration of the diets expressed as Mcal/kg DM ( P  ≥ 0.22) but did linearly reduce energy intake (Mcal/d; P  < 0.01). Feeding Alga 1.0 linearly reduced enteric CH 4 emissions measured as g/kg DMI ( P  < 0.01) by 39 and 64% for 69 g/d and 103 g/d inclusion, respectively. Linear reductions ( P  < 0.01) of 64% to 65% were also observed in enteric CH 4 emissions when expressed per kilogram of DM or organic matter digested. Respired CO 2 as g/d linearly decreased ( P  = 0.03) for cattle fed Alga 1.0 but did not differ when expressed as g/kg of DMI ( P  ≥ 0.23). Oxygen consumption did not differ between treatments for g/d and g/kg DMI ( P  ≥ 0.19). In conclusion, feeding Alga 1.0 reduced DMI up to 13.3%, did not impact digestibility, and significantly reduced CH 4 emissions up to 63%.