Abstract

Simple Summary In pasture-based dairy systems, supplementing the diet is crucial during periods when pasture availability is low. Field peas, which can be locally produced, offer relatively high concentrations of crude protein, along with significant energy content in the form of starch, all at a lower price. These qualities make field peas a sustainable alternative to traditional protein and energy sources such as soybean meal and corn grain. This study explored the impact of substituting traditional feeds with field peas in the concentrates of grazing dairy cows. Our findings indicate that using field peas maintains milk production and composition (protein and fat) without affecting intake or ruminal and blood parameters. This suggests that field peas are a viable alternative for feeding dairy cows, supporting consistent production under grazing conditions.Abstract This study assessed the effects of replacing soybean meal (SBM) and corn grain with field peas in the concentrate of grazing dairy cows on milk production, intake, ruminal fermentation, and blood indicators. Twelve multiparous lactating Holstein-Friesian cows were utilized in a replicated 3 x 3 Latin square design, comprising three periods and three treatments: (1) Pea-0 (Control diet): 6 kg dry matter (DM) of fresh pasture, 7.2 kg DM of grass silage, and 7 kg DM of a concentrate containing 0% pea; (2) Pea-30: Control diet with the concentrate composed of 30% pea; (3) Pea-60: Control diet with the concentrate composed of 60% pea. The effect of treatments on productive and metabolic parameters was evaluated using linear-mixed models. Pasture and total DM intake, milk production, and composition were unaffected by treatments. Despite the concentrates being isonitrogenous and isoenergetic, crude protein (CP) intake was slightly higher in Pea-30 and significantly higher in Pea-60 due to higher pasture CP content in the pasture grazed by these groups, leading to higher milk urea content, though within recommended ranges. Blood parameters showed no significant changes, except for plasma beta-hydroxybutyrate, which was lowest in the Pea-60 treatment; however, all values were within ranges not indicative of subclinical ketosis. Ruminal fermentation parameters were similar across treatments. These findings support the use of field peas as a viable alternative to replace SBM and corn grain in concentrates, enabling similar milk production and composition in grazing dairy cows.