Analytical and nutritional evaluation of rye grain in diets for growing pigs Climate change and increasing consumer awareness of environmental and animal welfare issues are constantly challenging the animal nutrition sector to adapt and find improved solutions that are resource efficient, meet the requirements of pigs and promote animal welfare. One such approach is the use of regional feedstuffs such as rye and rapeseed meal to feed pigs. In the past, both feedstuffs were rarely used in conventional pig feeds due to low yields and high concentrations of antinutritive substances. Further development of the varieties; more recent scientific findings; as well as their sensible use from economic, agronomic and animal nutrition points of view require a re-evaluation of rye grain (hybrid rye) and rapeseed meal. For this purpose, compound feeds made from wheat or rye grain were combined with soybean or rapeseed meal and compared regarding several research questions. The digestibility of phosphorus (P) with and without the supplementation of phytase in the aforementioned compound feeds was investigated, which is important on the one hand because of the finite nature of P and on the other hand because of the negative environmental impact of a surplus. The type of cereal grain had no influence on the P digestibility of the compound feeds; consequently, the high concentration of intrinsic phytase in rye compared with wheat had no influence on P digestibility. In the compound feeds with soybean or rapeseed meal, phytase supplementation produced the same P digestibility: 70.2% and 69.5%, respectively. Rye and rapeseed meal shifted nitrogen excretion from urine to faeces due to the higher fibre concentration compared with wheat and soybean meal, thus contributing to the reduction in ammonia release from manure. The metabolisable energy content in the compound feeds was ? 14.2 MJ/kg dry matter, which is suitable for growing pigs. Rye grain and rapeseed meal are both characterised by a high fibre content. Rye has a relatively high content of soluble dietary fibre, to which positive nutritional and health-promoting characteristics are attributed. Because the soluble and insoluble dietary fibre fractions can vary greatly in their composition and thus in their effect, a practicable procedure should be established to analyse all the individual carbohydrate fractions of the dietary fibres by means of enzymatic photometric, enzymatic gravimetric and chemical gravimetric methods and applied in feed and faecal samples. Due to many interfering factors and complex matrices, the establishment of such a method was not possible. Hence, alternative approaches were considered, whereby in particular sum parameters that subdivide fibre into soluble and insoluble fractions are currently the best practical approach for a differentiated fibre analysis. In the field of dietary fibre analysis, differences in the implementation and description of methods can be observed, which severely limit the comparability, so the scientific community must establish clear rules and definitions in this respect. The use of compound feeds containing rye grain and rapeseed meal is recommended for growing pigs based on the results obtained, using proper feed formulation and common feed additives such as phytase.