Hopp til hovedinnholdet

Publications

NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.

2023

To document

Abstract

Productive and stable forage yields are essential for the sustainability of ruminal livestock production. Grassland seed mixtures composed of species of diverse functional groups have previously been demonstrated to increase yield performance and stability compared to monocultures. In this study we conducted field trials with five grass and two legume species either grown in monocultures or a range of mixtures from two-species to seven-species mixtures sown in a simplex design. The species represented different functional groups regarding ability to fixate atmospheric nitrogen (N), rate of establishment and temporal persistence.The experiments were established with the same cultivars of species at five locations in Norway with climatically contrasting environments – from mild humid, mountainous continental to sub-arctic. The experimental plots were harvested for three years at four of the sites and two years at one of the sites, and they were fertilised according to normal practise in intensive silage grass production in the respective regions (regular N). At three of the sites, a treatment with low mineral N supply rate was also included.We found that crops sown as mixtures returned higher yields and contained less weeds than the average of monoculture crops, and these effects were consistent over all sites and study years. The grass-legume mixtures managed at low N supply rate performed equally well or better than monocultures or grass-only mixtures managed at regular N supply. We found no effects of the functional groups categorised as temporal persistence or rate of establishment on the yield performance, and there were no apparent benefits of increasing the number of species beyond the species P. pratense, F. pratensis and T. pratense over the three production years the experiments lasted.The results suggest that by using grass-clover mixtures, farmers can reduce N fertiliser rates, without compromising productivity of temporary grassland under northern conditions over the first three years of production.

To document

Abstract

Grasslands represent key functional ecosystems due to their global contribution to macronutrients cycling and their role as reservoirs of microbial diversity. The strategic importance of these habitats rests on their involvement in carbon and nitrogen fluxes from the atmosphere to the soil, while at the same time offering extensive sites for livestock rearing. In this study the management type, differentiated in pasture or meadow, was investigated as a variable for its possible effects on overall bacterial diversity and specific genes related to functional guilds. Its contribution was compared to that of other variables such as region, soil pH, and soil organic carbon, to rank their respective hierarchies in shaping microbial community structure. A latitudinal gradient across the European continent was studied, with three sampling groups located in Norway, France, and Northern Italy. The applied methods involved 16S DNA metabarcoding for taxonomic classification and determination of the relative abundance of the bacterial component, and quantitative PCR for the genetic determinants of bacterial and archaeal nitrification, intermediate or terminal denitrification, and nitrogen fixation. Results indicated that soil pH exerted the dominant role, affecting high taxonomy ranks and functions, along with organic carbon and region, with whom it partly covaried. In contrast, management type had no significant influence on microbial community structure and quantitative counts of functional genes. This suggests an ecological equivalence between the impacts of pasture and meadow practices, which are both perturbations that share the aspect of vegetation withdrawal by browsing or cutting, respectively.

Abstract

Increasing the protein value in grass silages for dairy cows is of interest to increase use of homegrown protein sources and reduce nitrogen (N) losses to the environment. Studies have shown that wilting of grass silage can improve the metabolizable protein (MP) value by increasing the rumen microbial protein yield (MCP) and rumen escaped feed protein. We hypothesised that feeding wilted grass silage can improve milk and milk protein production in dairy cows and reduce the need for MP, estimated as amino acids absorbed in the small intestine (AAT), in concentrate. To test this, a continuous feeding experiment with 48 early to mid-lactation Norwegian Red dairy cows, kept in a loose housing system was conducted. Treatments were first cut grass silages from round bales, harvested at early booting from a sward of timothy (Phleum pratense), perennial rye grass (Lolium perenne) and meadow fescue (Festuca pratensis), wilted to 260 and 417 g dry matter (DM)/kg fresh matter. The grass silage was fed ad libitum and supplied with 8.3 kg/d of concentrate, either low (108 g AAT/kg DM) or high (125 g AAT/kg DM) in MP concentration, in a 2×2 factorial arrangement. The experiment lasted for 11 weeks, with the 2 first weeks, where cows received same feeding, used as covariate, and the last 4 weeks were used as data collection period. Wilting reduced fermentation products, ammonia and soluble N in the grass silage, while increased residual water-soluble carbohydrates, like expected. However, there was no difference between treatments in daily silage DM intake (13.1 kg) and milk yield (30.2 kg) or milk content, but feeding high MP concentrate increased urea and uric acid in urine. No major differences were found for rumen pH, amino acids in blood plasma or purine derivatives over creatinine index, as indirect estimate for MCP. In conclusion, high silage DM and high MP in concentrate did not increase the milk production in this study.