Interest of dehydrated alfalfa in maize and grass silage diets for dairy cows

Abstract

Two trials were performed in order to study the interestof 3 kg dehydrated alfalfa (18% crude protein content, fibres of a few centimetres) in maize and grasssilage diets. Multiparous dairy cows (27 Montbeliardand 27 Holstein) received complete experimental dietsduring the first 15 weeks of lactation. The use of 3 kg dehydrated alfalfa permitted to reduce the quantity of soybean meal without reducing the energy and crudeprotein in the feed supply. DM intake was increasedwhen cows were fed alfalfa (23.4 versus 21.1 kg/d ; P<0.001). But this higher DM intake did not permit toincrease milk production which was 31.1 kg/d. Milk fat content was unaffected by the dehydrated alfalfa (43.0g/kg). Adding alfalfa increased milk protein content (31.2 versus 32.3 g/kg ; P<0.05) without changing the milk casein content. In this experiment with individually fed cows, we noticed that many dairy cows did not easily consume dehydrated alfalfa. Calculated nitrogen excretion was more important with the alfalfa diet(372 versus 321 g N/d ; P<0.001) because DM intake was higher with an inadequate N mobilisation in milk protein. At the beginning of lactation, weight and fattening score variations were unaffected by the diets. No difference was noticed for reproduction capacities. Although it is difficult to study animal health with only a few animals, added alfalfa might decrease mastitisrisks by improving animal health due to the neutralisation power of alfalfa and reducing acidos is conditions.