Physiological response of turkeys fed diets with a different content of fructooligosaccharides

The present study was carried out to determine the effects of a different content of fructooligosaccharides (FOS) on the performance and intestinal metabolism in turkeys. Diets containing 0%, 0.5%, 1% and 2% of FOS, fed to turkeys for 8 weeks, had no effect on feed intake, body weight and feed conversion. The highest FOS content significantly increased the weight of caecal digesta, and lowered the ileal and caecal pH, in comparison with the control group. FOS had no significant effect on the activity of microbial enzymes in the caecal digesta. The highest FOS addition enhanced the production of volatile fatty acids in the caeca (400.9 vs. 284.8 μmol/kg BW), especially butyrate (117.5 vs. 66.3 μmol/kg BW), in comparison with the control group. Compared to the highest FOS content (2%), the levels of 0.5% and 1% had no significant effect on the intestinal parameters of turkeys. Introduction In the last decade FOS were extensively studied for their ability to improve animal health and performance. In our earlier experiments [3], the addition of low doses of FOS (0.4%) had no significant effect on the body weights of turkeys, and negligibly changed SCFA concentration in the caecal digesta. A higher dose of FOS added to a broiler diet (2%) had no effect on the pH in the upper segments of the gastrointestinal tract, but reduced the caecal pH by 0.4 units [2]. Also a diet containing 2% of thermally produced kestose had no effect on weight gains, feed conversion and the count of intestinal microflora [5]. This shows that the physiological effects of dietary FOS have not been sufficiently investigated, especially in turkeys, which are sporadically used in experiments on diet supplementation with oligosaccharides. Thus, the aim of the present study was to determine and compare the effects of higher concentrations (0.5, 1% and 2%) of FOS in a diet for turkeys on their performance and intestinal parameters. Material and Methods The 8-weeks experiment was conducted on 320 three-day-old BUT-9 male turkey poults, randomly assigned to one of four dietary treatments (four replications with 20 poults in each group). The poults were given free access to mash diets formulated to meet nutrient requirements of turkeys [4]. The basal diet was supplemented with 2% of wheat (control group) or 1.5%, 1% and 0% of wheat and 0.5%, 1% and 2% of FOS (FOS-0.5, FOS-1 and FOS-2, respectively). As source of FOS preparation of Raftilose P95 (ORAFTI, Belgium) was used. After 8 weeks of experiment feeding, eight turkeys representing an average body weight of each group were killed. The selected parts of the digestive tract were removed and weighed. Ileal and caecal pH was measured using a microelectrode and pH/ION meter (model 301, Hanna Instruments). Samples of fresh digesta were used for chemical analysis. Microbial enzyme activity in the caecal digesta was measured by the rate of por o-nitrophenol release from their nitrophenylglucosides [1]. The VFA concentration was analysed by gas chromatography (Shimadzu GC-14A with a glass column 2.5 m × 2.6 mm, containing 10% SP-1200/1% H3PO4 on 80/100 Chromosorb W AW, column temperature 110oC, detector