Faba beans (Vicia faba) in dairy cow diet: effect on milk production and quality

The use of alternative plant proteins in place of the soybean meal protein in diets for farmed animals aims to reduce the extra-EU soybean import and partially substitute the GMO in the food chain. Among the possible alternatives, the heat-processed (flaked) faba beans appears interesting for dairy cow diet. Two consecutive experiments were carried out to test flaked faba beans as a partial substitute for soybean meal in the diet of Reggiana breed dairy cows producing milk for Parmigiano-Reggiano cheese-making. In both experiments a "Control" concentrate (12% soybean meal, no faba beans) was compared with a "Faba" concentrate (7.5% soybean meal and 10% flaked faba beans). Forages fed to animals were hay (mixed grass and alfalfa) plus mixed grass in experiment 1, hay only in experiment 2. Milk yield and quality and the characteristics of grab faecal samples as empirical indicators of digestibility, were similar between feeding groups. The milk urea content was slightly lower in the "Faba" group, particularly in experiment 2 ("Control" vs "Faba": 34.6 vs 32.9 mg/dL in experiment 1, P<0.1; 27.4 vs 23.4 mg/dL in experiment 2, P<0.01); the plasma urea content in experiment 2 confirmed the trend observed in milk (3.9 vs 3.0 mmol/L, P<0.01).