Whole-crop cereals in dairy production

The four studies summarised and discussed in this thesis evaluate the use of whole-crop cereal silage (WCCS) for cattle in dairy production. The dry matter (DM) yield, chemical composition, digestibility, feed intake and milk production for WCCS were evaluated for different cereal species and maturity stages at harvest. The DM yield increased from milk to dough stages of maturity and was higher in winter triticale and rye than in spring barley and oats. Delayed harvest until early dough stage decreased the crude protein (CP) and neutral detergent fibre (NDF) concentrations in barley, oats and triticale. The concentration of water soluble carbohydrates (WSC) of the fresh crop was highest at the early milk stage, but these carbohydrates were to a large extent polymerised to starch by the early dough stage of maturity. Both WSC and starch concentrations were lower in oats than in barley, triticale and rye. When fed to dairy heifers the DM intake (DMI) of six-rowed barley was reduced at early milk and early dough stages most likely due to the development of sharp awns on the crop. The DMI of six-rowed barley silage also decreased with delayed maturity stage when fed to dairy cows. The DMI of oats was reduced at the heading and early milk stages of maturity due to low DM content of the silages. The DM digestibilities and organic matter digestibilities (OMD) of oats and winter rye were lower than for barley and winter triticale, as a combined effect of higher NDF concentrations and lower NDF digestibilities in the two former crops. When six-rowed barley silage harvested at the early dough stage was fed to dairy cows in mid-late lactation the daily energy-corrected milk (ECM) yield was 3 kg lower than when barley silage at heading was fed, due to reductions in milk yield, and both protein and fat concentrations in the milk. This decrease in ECM yield was due to lower DMI and OMD of the ration containing barley silage at early dough stage than of the ration including barley silage at the heading stage of maturity. In conclusion, spring barley and winter triticale appear to have the best feed values when chemical composition and digestibility are considered. When WCCS harvested at early dough stage is fed to dairy cows, milk production may decrease