Feeding Behaviour and Faecal Particle Size in Lambs Fed Concentrate-Based Diets with Grass and Maize Silages of Various Feed Values

Maize silage is increasingly used for ruminants in Nordic countries. We evaluated effects of maize maturity at harvest and maize silage inclusion rate on intake, dietary selection, chewing behaviour and faecal particle size in lambs fed concentrate-based diets. Forty crossbred ram lambs were housed in pairs (five pens per treatment) in a 2 × 2 factorial arrangement. Diets contained 58% concentrate and 42% forage (dry matter (DM) basis); forage was early- (dough stage) or late-harvested (dent stage) maize silage, alone or mixed 50:50 with grass silage. After approximately three weeks on the diets, data were collected over four days, including 24 h of video-recorded behaviour. Daily DM and neutral detergent fibre (NDF) intakes were not affected by diet. Refusals contained more NDF, more particles of 8–19 mm and <1 mm and fewer particles of 1–8 mm than the offered feed; selection for 1–8 mm particles was greatest with late-harvested maize as the sole forage. Lambs fed maize silage as sole forage spent less time eating (daily and per kg DM intake) and had fewer faecal particles <0.212 mm and more of 0.212–0.500 mm than lambs fed grass–maize diets. Maturity and inclusion rate had limited effects on intake and feeding behaviour.