Sugars: are a relatively simple carbohydrates (CHO) that are very readily available to the rumen bugs as a primary source of energy to aid microbial activity and increase microbial populations. 

Sugars range in complexity from glucose and fructose to sucrose and lactose (milk sugars). Forages are typically high in glucose and fructose, therefore it is assumed that forage sugars are utilised fully in the rumen. 

Lactating rations are typically formulated to supply in the order of 80 – 100g total sugars per kg of dry matter (DM). Research has not shown any significant or consistent production gains by increasing above these levels. Sugars are primarily fermented to butyric acid in the rumen. Excessive volumes of butyrate have been shown to interfere with rumen motility, which may predispose cows to SARA.