Intake and digestibility in cattle grazing temperate grass associated with legume and/or energetic supplementation

The intercrop between grasses and legumes is an alternative to maintain and increase animal production. The study was conducted to evaluate the effect of grass-legume mixtures with or without supplementations on rumen fermentation, nutrient intake, and microbial protein synthesis. Six Holstein steers fitted with ruminal cannula were kept in a double 3 × 3 Latin square design. The treatments were: 1) oat, annual ryegrass, and supplement (GS), 2) oat, annual ryegrass, and vetch (GL), 3) oat, annual ryegrass, vetch, and supplement (GLS). Supplementation of ground maize was given daily at 11 h at 1% of body weight. Total digestible nutrient intake was higher in steers fed GS and GLS. Animals on GL ingested higher concentrations of nitrogen (N) compared to animals on GS and GLS diets. Ruminal pH and ammonia concentration were higher in GL. Grass-legume mixtures and supplements showed higher concentrations of sugar, α-amino acids, and peptides. The ruminal fermentative parameters, ruminal pH, ammonia, and sugars ranged cubically across the day. Microbial protein synthesis was similar amongst the treatments. Animals exclusively consuming temperate grass produce higher ruminal pH and ammonia concentrations. Therefore, using temperate legumes in pasture systems can be included in the cattle diet in lieu of utilizing energy supplements.