Methane is a strong greenhouse gas, and dairy cows are a significant source of methane in the agricultural sector. This study evaluated how the use of farm-specific dietary information, compared with standard assumptions, influences estimate of enteric methane emissions across different dairy and double-purpose cow breeds in Italian farms. Data from 138 farms rearing two Italian dairy breeds (Holstein, Brown Swiss) and a double-purpose breed (Italian Red Pied) were analyzed. Farm-level data on milk production, herd characteristics, and cow diets were used to reflect real feeding conditions and improve the accuracy of methane emission estimates. The results showed that Holstein lactating cows produced overall the highest quantity of milk, as well as methane emissions per day. Conversely, Italian Red Pied cows had the highest methane emissions per kilogram of milk produced. This suggests a trade-off has to be found between productivity and environmental impact. The incorporation of farm-specific ration data on herd diet in different farms resulted in a substantial change of emission estimates, particularly for young and dry cows. The availability of accurate farm-level data could enhance the precision of methane estimates and facilitates the identification of more environmentally efficient dairy systems.

Read the full article in the Journal of Animal Science.