Tomas Persson
Forsker
(+47) 466 30 485
tomas.persson@nibio.no
Sted
Særheim
Besøksadresse
Postvegen 213, NO-4353 Klepp stasjon
Sammendrag
Med helgrøde mener vi vanligvis korn eller frøvekster der hele planten høstes og konserveres for bruk som grovfôr til drøvtyggere. Her oppsummerer vi forsøksresultat og praktiske erfaringer med kornhelgrøde.
Sammendrag
Ensiling is a common mode of preservation of animal feed. In this process, the feed undergoes lactic acid fermentation in an anaerobic environment, which decreases pH and inhibits degradation of the feed and its nutritive value. Common silos include top loaded tower silos, side loaded bunker silos (also called horizontal silos), underground pit and trench silos, and bales and tubes wrapped in plastic film. Previous studies have revealed that the type of silo often have an impact on silage properties and feed value, but these effects can vary between silage materials. Silage density is another key factor for silage nutritive value and losses. Generally, high density results in smaller losses than low density, both in bunker silos and bales, but the density effect can also be influenced by properties of the ensiled material. The objectives of this literature review were to identify factors and conditions that can modify the effect of i) silage density, and ii) silo type on dry matter losses, leaching of nutrients, fermentation characteristics, silage feed value and mycotoxins contamination. A systematic literature search was carried out in in the Web of Science core collection platform of databases. Most studies showed positive correlations between silage density, and fermentation and feed value, and negative correlations with DM losses. The majority of these studies were conducted at laboratory scale and there was also a great variation in the magnitude of these effects. Further investigations at farm scale may provide more information about the consistency of these effects across experimental scales. The silo type comparisons indicate that silage bales, bags and tubes can be favourable for silage quality and dry matter preservation compared to bunker silos, but information on silo type effects on important crops such as maize is missing.
Sammendrag
Ensiling of whole-crop biomass of barley before full maturity is common practice in regions with a short growing season. The developmental stage of barley at harvest can have a large impact on yield and nutritive composition. The relationships between crop growth, environmental conditions and crop management can be described in process-based simulation models. Some models, including the Basic Grassland (BASGRA) model, have been developed to simulate the yield and nutritive value of forage grasses, and usually evaluated against metrics of relevance for whole-crop silage. The objectives of this study were to: i) modify the BASGRA model to simulate whole-crop spring barley; ii) evaluate the performance of this model against empirical data on dry matter (DM) yield and nutritive value attributes from field experiments, divided into geographical regions; and iii) evaluate DM yield, nutritive value and cutting date under current and future climate conditions for three locations in Sweden and four cutting regimes. Main model modifications included addition of a spike pool, equations for carbon (C) and nitrogen (N) allocation to the spike pool and equations for C and N translocation from vegetative plant parts to spikes. Model calibration and validation against field trial data from Sweden, including samples harvested from late anthesis stage to hard dough stage that were either pooled or divided into regions, showed better prediction accuracy, evaluated as normalised root mean squared error (RMSE), of neutral detergent fibre (NDF) (7.58–18.4%) than of DM yield (16.8–27.8%), crude protein (15.5–23.2%) or digestible organic matter in the DM (DOMD) (12.0–22.2%). Model prediction using weather data representing 1990–2020 and 2021–2040 climate conditions for three locations in Sweden (Skara, Umeå, Uppsala) showed lower DM yield, earlier harvest and slightly higher NDF concentration on average (across locations and developmental stage at cutting) when using near-future climate data rather than historical data. The model can be used to evaluate whole-crop barley performance under production conditions in Sweden or in other countries with similar climate, soils and crop management regimes.
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