Fodder systems and environmental impact of cow milk production in Italy

Take home message. Fodder systems choices can change the environmental impact of milk production in dairy cow farms. Fodder systems based on permanent and multiannual crops, as grassland and lucerne, can be helpful in mitigating environmental load of milk production compared to systems based on arable crops, as maize or winter cereals. Introduction. Animal feeding, and in particular protein feeding, is a critical point in the livestock sector. The choice of crop system for home-grown fodder production can be crucial in the environmental prospective, it can affect feed self-sufficiency, amount and type of purchased feeds, efficiency of feed conversion, stocking rate but also the use of fertilizers and fuel consumption in field operations. The aim of the study was to evaluate, through a Life Cycle Assessment approach, the environmental impact of milk production in three groups of farms, characterized by different fodder systems. Material and methods. Inventory data about milk production, herd composition, feeding rations, housing system, manure management and crop production from 17 dairy farms of the Po plain were collected. Farms were divided in three groups on the basis of percentage of land with permanent and multiannual fodder crops (grassland or lucerne) on the total fodder agricultural area (Multiannual). Grazing was not adopted by any farm. Feeding ration composition were calculated using CPM-Dairy Ration software. Gas emissions were estimated according to IPCC (2006) and EEA (2009). Environmental impact categories, expressed per kg of Fat and Protein Corrected Milk (FPCM), were estimated with the methods recommended by ILCD Handbook (IES, 2012) and using the SIMAPRO software (Prè Consultants 2014). Results & Discussion. Farms with less than 20% of Multiannual were characterized by the smallest agricultural area, the largest herd size and the lowest dairy efficiency (59 ha, 176 lactating cows and 1.11 kg milk/kg dry matter intake on average, respectively). The most productive herds were in the intermediate group (20-50% of Multiannual) with 27.4 kg FPCM/cow per year, while the last group of farms, characterized by >50% of Multiannual, showed the lowest stocking density (3.39 LU/ha) and the lowest use of nitrogen from synthetic fertilizer (22 kg/ha per year). The results of impact categories showed the lowest values in the group of farms with >50% Multiannual. In particular, climate change per kg FPCM decreased as percentage of Multiannual increased; at the same time also feed self-sufficiency, both as dry matter and as crude protein, tended to increase, probably because the farms with >50% Multiannual were able to reduce the quota of high impact purchased feeds (particularly soybean meal, one of the most impactful feed on climate change) without compromising milk production. The same farms used the lowest amount of nitrogen fertilizer (both synthetic and organic), thanks to the low presence of annual crops, with an important restrain of acidification. Conclusion. Fodder systems characterized by extensive use of permanent and multiannual crops, as grassland and lucerne, can reduce the environmental impact of milk production in comparison to systems based on arable land due to the high amount of feed self-production, both energy and protein feeds, and the reduced use of nitrogen fertilizers.