Feed intake, ruminal parameters, milk production and economy in Holstein cows fed reduced forage or non-forage emergency diets

• It is possible to keep cows milking in a period of extreme shortage of forage by replacing commonly forage-based rations with non-forage rations containing straw and concentrate • Milk fat percentage, milk fat yield and energy-corrected milk yield were lower with high concentrate levels and milk fat depression was more severe when feeding a rapeseed small grain-based concentrate compared with a corn-soy alternative • Milk fat and production response were highly correlated with ruminal propionate proportion. • Income over feed cost decreased as the proportion of concentrate in the ration was increased We evaluated how to maintain dairy herds in a productive state after extreme drought episodes via substituting high quality forage (corn and grass-clover silages) with concentrate and straw. Ninety Holstein cows were allocated to a randomized trial for 11 weeks. The planned roughage-to-concentrate ratios (% of dietary DM) of the diets were: 51:49, 30:70, and 9:91. Two different concentrate palettes were used to substitute forage representing domestic (RGB) and globally (COS) available feedstuffs. The concentrate mixture RGB contained only feedstuffs that can be produced in the European Union. The RGB mixture contained starch from the feedstuffs ground barley and NaOH-treated whole wheat kernels, fibers from dried beet pulp and distiller’s dried grains (DDGS) and protein from rapeseed cake and DDGS. The concentrate mixture COS was based on globally available feedstuffs and contained starch from corn (ground kernels), fiber from soyhulls, and protein mainly from soybean meal. Treatments did not affect concentrate intake in milking robots, whereas intake of the partially mixed rations was 0.6 kg DM per day less with RGB when compared to COS. Milk fat concentrations were severely reduced with greater concentrate intake and reflected ruminal molar proportions of acetate to propionate. The study showed that it is possible to use concentrate-based emergency rations to keep dairy herds milking after severe drought episodes with a shortage of forage, however, the loss in milk fat yield implies that farmers should prioritize forage, even when prices are up to 2.5 to 3.3 times the standard production cost.