Field beans and soybean meal promote better growth and nutrient utilization compared with brewers’ spent grains when fed as the main protein source for growing beef cattle. Growing beef cattle that were fed a diet consisting solely of Italian ryegrass reduced enteric methane emissions per kg of feed consumed without affecting methane intensity but also reduced their growth rate and efficiency in using dietary energy and nitrogen, compared with beef under diets including more concentrate feeds. Feeding more pasture can reduce methane emissions on a g/d basis, but the inefficiencies in nutrient utilization could also have a negative environmental impact. While pasture feeding may lower emissions overall, poorer growth rates could lead to higher emissions per unit of production, as longer periods would be required to reach a similar endpoint. To balance the overall sustainability of this practice, the slower growth of animals in pasture-based diets should also be accounted for, especially when considering this system as an alternative to concentrate-based diets.

Read the full article in the Journal of Animal Science.