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

Abstract

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.