Pea (Pisum sativum) in dairy cow diet: effect on milk production and quality

The use of alternative plant protein in place of soybean meal protein in diets for farmed animals aims to reduce the extra-EU soybean import and partially substitute GMO in the food chain. Among the possible alternatives, the heat-processed (flaked) pea appears interesting in dairy cow diets. Two consecutive experiments were carried out to test flaked peas 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 (8.3% soybean meal) was compared to a "Pea" concentrate (5% soybean meal and 15% flaked peas). Forages fed to animals included mixed grass hay and alfalfa hay in experiment 1, and hay (mixed grass and alfalfa) plus mixed grass in experiment 2. Milk yield and quality, and the characteristics of grab faecal samples, examined to get some empirical indicators of digestibility, were similar between feeding groups. Compositional changes (crude protein and solubility) in forages used as common base in the diets of both experiments had a slight effect on milk and plasma urea contents. There was a tendency for a higher milk urea content in the "Pea" group (32.3 vs 30.1mg/dl in experiment 1, P<0.1; 30.2 vs 28.0mg/dl in experiment 2, P<0.1). The plasma urea content was different only in experiment 2 (4.9 vs 5.6mmol/l, respectively for "Control" and "Pea" groups; P<0.05).