Effect of maturity stage and chopping length of maize silage on particle size reduction in dairy cows

Abstract

The effects of maturity stage and chopping length of maize silage on chewing behaviour, particle size reduction and rumen retention time were studied in four lactating cows fitted with a ruminal cannula, according to a 4 × 4 Latin square design. Maize silage made up 80% of the diet and the cows were fed at 90% of the ad libitum intake level. Chopping length had only a significant effect on the particle size of the maize harvested at the late maturity stage. For the latter, the proportion of particles larger than 2 mm (LP2) from the feed to the rumen content decreased from 73 to 38% for the coarse maize and from 58 to 37% for the fine maize, mainly by ingestive mastication. Eating time expressed per unit of feed intake did not vary significantly between these two silages (21.3 vs. 19.8 min·kg-1 DMI). Ingestive mastication in dairy cows thus reduces long particles more efficiently than short particles.