Reticulo-rumen Fermentation in Dairy Cows Fed 12 Times Daily with 3 Types of Roughages Supplemented with Straw and Concentrates

Abstract

The aim of this experiment was to compare the effect of the roughage type on the reticulorumen fermentation, when included in rations having nearly the same chewing time and net energy. The design of the experiment was a 3×3 latin-square with 3 types of roughages and 3 dairy cows fed 3 times maintenance. The 3 test-roughages compared were grass silage, finely chopped maize silage and NaOH-treated chopped barley straw. The test-roughages accounted for approx. 6–7 kg DM, which was supplemented with 2–5 kg ammonia-treated barley straw and 6–8 kg concentrates. The cows were fed every second hour. The 3 rations differed significantly in terms of the concentration of isobutyrate, n-valerate, isovalerate and capronate in the rumen fluid. Feeding grass silage resulted in the significantly lowest molar proportion of acetate and the highest molar percentage of propionate (p< 0.05), whereas NaOH-treated chopped straw led to the highest molar proportion of acetate. Feeding grass silage resulted in a 12% lower acetate/propionate ratio and a 16% lower NGR-value compared to feeding maize silage or NaOH-treated barley straw.

Key Words:

• dairy cow
• kind of roughage
• chewing time
• rumen pH
• concentration of VFA
• pattern of fermentation