Organic farming and the impact of fiber-related digestive processes in pigs

Abstract

Samples of different cultivars of wheat, faba beans and barley, each of conventional and organic cultivation of the same location and year, were analyzed for their nutrient contents. In wheat, crops grown organically showed significantly reduced content of crude protein, whereas starch and fiber content tended to be increased. Organically grown barley tended toward significantly lower protein and higher starch content than conventionally grown cultivars. Fiber content was similarly increased. In faba beans the content of crude protein and fiber was affected by organic farming in the same manner as the cereal cultivars. The content of starch was also significantly reduced.Assuming that organic feeding results in an elevated supply of fiber, 2-factorial experiments with three different breeds, (Schwäbisch-Hällisches Schwein (SH), Buntes Bentheimer Schwein (BB) and modern crossbreed pig (CB)) and two different diets (basal diet (BD) and basal diet + sugar beet pulp (SBP)) were carried out in order to study fiber-related digestive processes. The basal diet was calculated to meet 80 % of energy and 100 % of amino acid requirements for average daily body weight gains of 700 g/d. Pigs had average bodyweights of 35 40 kg and were first used for metabolic trials. After this pigs were slaughtered and their caecum contents used for the Colon Simulation Technique (COSITEC) and for microcalorimeter experiments. Samples of jejunum and colon mucosa were taken for the measurement of electrophysiological transport parameters according to the Ussing-Chamber-procedure.The supplementary fiber of SBP, essentially consisting of unlignified soluble non-starch polysaccharides, was highly digestible whereas the digestibilities of all other nutrients were significantly reduced after feeding the SBP-diet. Urine N was reduced and fecal N increased with the fiber rich diet. Compared to the BD-fed group, caecum contents taken from SBP-fed pigs led to higher fermentation intensity in the COSITEC and higher microbial activity in microcalorimeter experiments. N- and mineral-retentions (Ca, Mg, Na, K) of the pigs were also increased after feeding the SBP-diet.The ability to digest high fiber feedstuffs differed among the three breeds. However, there was no clear indication for higher fiber degradation in the old pig breeds, with SH showing a lower digestion than BB and CB.The results on digestive physiology as well as those on electrophysiological mucosal membrane transport indicate significant influences of soluble NSP and pig breed on precaecal digestive processes. Specific investigations are necessary to clarify their impact for intestinal nutrient utilization and animal health.In order to investigate the influence of organic diets on digestive processes an additional 2-factorial experiment with two different breeds, Buntes Bentheimer Schwein (BB) and modern crossbreed pig (CB)) and two different diets (conventional diet (CD) and organic diet (OD)) was carried out as a metabolic trial.Feeding the OD resulted in significantly reduced digestibilities for nearly all nutrients, except for ether extract and NfE. N- and mineral retentions except for phosphorous were not significantly influenced by the diet. Nutrient digestibilities were higher for BB pigs compared to CB pigs when the organic diet was fed.These results together with those achieved for the SBP addition indicate significant influences of the nutrition on digestive physiology, which are very different between the pig breeds. It must be theme of further investigations, how strong the impact of both, a fiber addition combined with factors being associated with organic diets, is on digestive processes, to draw valid conclusions on the suitability of certain pig breeds for organic farming.