The use of partly-hydrolyzed and untreated straw meal in the feeding of breeding sows. 5. Concentration, production and absorption of volatile fatty acids in the large intestine

In 2 experiments with a total of 28 breeding sows of the country species studies were made of the fermentation, production and absorption of volatile fatty acids (VFA) in the large intestine after feeding variously treated straw materials in concentrate--straw meal mixtures. Experiment 1 ascertained that supplements of untreated (I), HCl treated (II) and partly hydrolysed straw meal (III, treatment with subsequent steaming) caused a decrease of the VFA concentration as well as considerable molar changes of the VFA in the caecal and colonal digesta in comparison of the sole feeding with concentrate (IV). The straw fibre integration increased the molar acetate quota at the expense decreased propionate and butyrate fermentation. Considering the straw meal variants this effects was least distinct after the feeding of partly hydrolysed straw meal (III). In experiment 2, which comprised the simultaneous ascertainment of VFA production in the feeding variants I and III and which was based on a representative number of animals per test group (n = 10), there were significant differences between the production quotas (I = 992; III = 1,300 mmol/animal.d) and in the absorption quotas of VFA (I = 63; II = 78%). The digestible energy from the VFA in the large intestine amounted to 711 kJ/d (I) and 1,183 kJ/d (III). The derived higher net energy gain from the hydrolysed straw product (III) was calculated at 590 kJ (40EFUpig/kg DM) and discussed together with results of feed value increase from the digestibility experiments.