Effects of forage NDF content and body condition score on forage intake by Holstein-Friesian dairy cows in the dry period

This study used individual weekly results for 160 non-lactating Holstein–Friesian dairy cows in the last 5 weeks of gestation to develop regression equations based on forage NDF content and individual body condition score (BCS) for predicting dry matter (DM) intake. Results were used from treatments in which cows received the same forage and no concentrates throughout the dry period. Ten different conserved forages, either grass silages or mixtures of grass silage and barley straw, were fed in six different experiments and forage NDF ranged from 452 to 689 g/kg DM. On average cows gained 390 g live weight per day, which is less than conceptus growth at this stage – suggesting some mobilisation of maternal tissues to support conceptus growth. BCS remained unchanged at 2.5 over the dry period. DM intake declined from 10.79 kg/day 5 weeks before calving to 9.32 kg/day in the week before calving, with half of this decline occurring in the final week before calving. Intake as a percentage of live weight was moderately predicted (R2 = 0.61 for the entire period) from measures of diet composition (NDF) and cow state (BCS). There were highly significant negative effects of forage NDF and increased BCS on DM intake. The effect of BCS on DM intake was greatly reduced in the week before calving, possibly as a result of a change in metabolic priorities from gaining to losing body reserves