Environmental impact and food production of small-scale mountain dairy farms at different supplementation levels

Abstract

In mountain areas such as South Tyrol, Italy, in addition to extensively managed farms with dual-purpose breeds, there is an increasing number of farms raising high-yielding breeds, that depend on large quantities of concentrated feed imported from other regions. A large supply of nutrients not only leads to unbalanced nutrient budgets but also to a lower contribution to net human food supply by using large amounts of human edible feedstuff. 64 dairy farms managed at differing concentrated feed intensity levels in South Tyrol were assessed. The farms were divided into four groups according to the amount of concentrated feed used (high [H] vs. low [L]) and the breed (Tyrolean Grey [TG] vs. Brown Swiss [BS]). The following groups were analyzed: H-BS with ⌀ 8.7, H-TG with ⌀ 6.1, L-BS with ⌀ 4.0 and L-TG with ⌀2.8 kg concentrated feed per cow and day. Farms cultivated only permanent grassland without any cash crops. N budgets for H-BS, H-TG, L-BS and L-TG were 79.54, 50.81, 37.85 and 34.16 kg ha−1, respectively, with significantly higher values for H-BS compared to the other groups. P and K budgets were also significantly higher for H-BS (12.8 and 43.96 kg ha−1, respectively) when compared to L-BS (3.10 and 8.86 kg ha−1) and L-TG (1.50 and 11.91 kg ha−1). The nutrient use efficiency, calculated as the proportion of output to input, for N and K was similar across all groups, while the P-efficiency was significantly higher in L-BS and L-TG (91.3 and 98.5%, respectively) compared to H-BS and H-TG (73.0 and 72.4%, respectively). HeFCE for protein and energy was lowest for H-TG (0.99 and 2.38, respectively) compared to L-TG (1.54 and 3.73, respectively), with the decisive factor being the amount of concentrated feed per kg ECM produced (g DM/kg ECM).