Milk production, feeding systems and environmental impact of dairy cattle farming in Alpine areas : results of a field study

Intensification of milk production occurs even in areas traditionally characterized by low-intensive farming systems like mountain areas, leading to environmental concern. The aim of this study was to analyze management and feeding systems in a sample of 31 dairy farms in a mountain area of Lombardy (Valtellina) and their effects on milk production and environmental sustainability. In 2006 daily milk sold was 17.5±5.6 kg/cow on average and daily DMI was 19.4±1.3 kg/cow, with a high forages content (65.8±9.2% DM). Rations were quite energetically balanced (+0.09±17.6 MJ/d of ME). Rations higher in starch and lower in NDF resulted in higher milk yields but significantly compromised farm self-sufficiency (which was 62.9±16.8% DM on average). Average Metabolizable Protein balance was negative (-280±203 g/d of MP), mainly due to the low CP content of diets (13.5±1.5% DM). When CP content increased, N manure and N excreted in urine increased (P<0.05 and P<0.01 respectively), probably due to insufficient energy intake which is partly caused by the scarce quality of forages. An improvement in forages quality could increase ME and MP contents of diets without compromising farm self-sufficiency.