REVIEW: Effect of forage provision on feed intake in dairy calves

The literature shows inconsistent results on the effect of forage availability on calf starter intake. This review aims to comprehend why these discrepancies are observed by analyzing this issue from a different perspective. Forage can have a positive effect on starter intake when starter consumption puts the calf at risk of rumen acidosis and can reduce starter intake when there is no risk of acidosis. Calf age; intake level; and the nutrient composition, physical form, and palatability of both starter and forage will affect the risk for rumen acidosis and the response of the calf to forage availability. Intake and fermentation rate of fermentable carbohydrates, primarily starch, will have the largest effect on rumen acidosis and the need for or benefit from having forage in the diet. Grain particle size and processing affect the fermentation rate of starch in the rumen, and often the trials that found forage had a positive effect on starter intake were those studying complete pellet starters. Most reports where forage had a negative or no effect on starter intake studied texturized starters where starch fermentation is slow. Calf age during the experiment also has a large effect on the effects of feeding forage.