The use of a partly-hydrolysed straw meal in the feeding of weaned piglets. 2. Concentration and production of volatile fatty acids in the large intestine by the use of test rations with various portions of straw

Abstract

The ad libitum influence of various quotas of partly hydrolysed straw meal (PHSM) on the fermentation and production of volatile fatty acids (VFA) in the colon in the measuring periods 2nd and 8th weeks of keeping was checked within a feeding experiment with weaned piglets of the country species (42nd-98th day of life; 1st-8th week of keeping). The straw hydrolysis product was fed in a parallel experiment without or after neutralization with CaCO3 in quotas of, 5, 10 and 15% related to dry matter in comparison to the feeding of sole concentrate feed. The measuring in the 2nd week of keeping (adaptation phase) was blurred by the diarrhea in the groups with regard to the concentration, production and molar proportion of VFA. The concentration and production quota of VFA was diminished and the C2:C3 relation as well as the molar quota of branched-chain fatty acids increased in the comparison of the groups above all under the feeding conditions of the sole use of concentrate and--less distinctly--of quotas of 5% PHSM (insufficient dietetic effect) in the feed mixture. Measuring in the 8th week, in which diarrhea did not play a role in any of the groups, showed a significant, ration specific influence on the fermentation pattern of VFA. With the increasing quota of PHSM in the feed mixture (x) a significantly positive relation with the molar acetate quota (y) could be calculated (y = 52.6 + 0.36x;r = 0.50). The C2:C3 relation after sole concentrate feeding rose to 2.6:1 at a 15% PHSM integration. In this, the molar increase of acetate was predominantly linked with a decrease of the butyrate and valerate quotas. A falling tendency of the molar iso-acid quota in the colon digesta was registered with the growing straw quota in the feed mixture. The daily production quota of VFA varied in the measuring period in the 8th week of keeping between 400 and 800 mmol/animal.d without an ascertainable influence of the crude fibre quota of the straw. In comparative calculations with other test results, however, a significant positive correlation between the daily intake of digestible organic matter and the production of VFA in the large intestine could be proved.