[Effect of thermal treatment of potato products on nutrient decomposition in the digestive tract of swine. 1. Passage and digestibility of nutrients in the various portions of the intestine].

In addition to a basic ration (barley, dried green fodder, fishmeal) pigs (castrated males, 100 ... 130 kg live weight) received a supplement of raw potato starch, raw ensiled potatoes, cooked potato starch or steamed ensiled potatoes; nutrient and amino acid passage and digestibility (absorption) were measured in the small intestine, the upper large intestine and the total digestive tract with the help of simple cannulae at the distal ileum and the middle of the hind gut and the estimation of the HCl insoluble ash as an indicator. In addition, the amounts of bacteria in faeces were determined and the influence of raw and cooked potato starch on N retention was ascertained. When raw potato products were fed, distinctly higher amounts of dry matter, organic matter and starch pass the ileum, which get into the colon undigested, i.e. the digestibility of these substances is low at the end of the ileum (raw potato starch 24%, starch of raw ensiled potatoes 36%). Up to the middle of the colon there is intensive bacterial starch degradation so that in this place the difference between raw and thermically treated potatoes is only small. No matter what the previous treatment of the potatoes was, there is hardly any starch in faeces, i.e. it was nearly 100% digested up to the end of the digestive tract. The passage and digestibility resp. of ash and crude cellulose from the basic ration is not influenced by the supplement of raw or thermically treated potato products in the individual sections of the digestive tract. At the end of the ileum there are no differences between the apparent digestibility of the crude protein and absorption of amino acids of supplemented raw or cooked potato starch or steamed ensiled potatoes; after the use of raw ensiled potatoes they are, however, significantly more reduced than the comparison of analyses of faeces shows. In the large intestine the high amount of potato starch stimulates the metabolism and the reproduction of faecal bacteria as is shown by an increase by 20-30% in bacteria N excretion in faeces. Apparent crude protein digestibility and amino acid absorption are diminished by that. The increased N excretion in faeces after the supplement of raw potato starch to the basic ration is-in comparison with the supplement of heated starch-compensated by a commensurately lower N excretion in urine so that N retention practically remains uninfluenced by the supplement of variously treated potato starch.(ABSTRACT TRUNCATED AT 400 WORDS)