[Structure in rations of dairy cattle (author's transl)]

Efficient utilization of feed by ruminants is closely related to fermentation in the reticulum and rumen. A deficiency is long roughage ("structural material") may impair this fermentation and result in a low-milk fat syndrome. The deficiency in long roughage is particularly apparent in diets containing large amounts of readily available carbohydrates. Factors involved in the absence of structure were described. Readily available carbohydrates such as sugars and starch from grains will promote high concentrations of volatile fatty acids in the rumen. Chewing and ruminating stimulate the secretion of salive and so increase the buffering capacity of the rumen fluid. tlong roughage is required to maintain the structural layer in the rumen, inducing regular and rigorous contractions. The buffering capacity in conjunction with adequate rumen motility may partly reduce the effect of high concentrations of volatile fatty acids produced from high amounts of readily available carbohydrates. Coarseness and type of roughage also are important factors. At least one-third of the total uptake of dry matter should consist in long, coarse and fibrous roughage. Extremely high concentrations of volatile fatty acids in the rumen of high-yielding cows may be reduced to some extent by providing the mixture of concentrates in more meals a day at intervals of at least 3-4 hours.