1,721,275 research outputs found
Parameters influencing preference by sheep in soft leaved tall fescue genotypes
No full textAn important disadvantage of tall fescue ( Festuca arundinacea Schreb.) is its low voluntary intake, resulting in suboptimal performances of cattle grazing tall fescue. Ideally selection for this trait is done by animals themselves, but the use of grazing animals in large breeding programmes is laborious. Repeatable, stable and quantifi able parameters that can be linked to animal preference could ease tall fescue breeding. We established a trial to fi nd relations between the grazing preference of sheep and other plant parameters. Twenty clones were selected from a breeding programme and swards of 2 m 2 were planted with three replications for each clone. On four different occasions in 2014, sheep were allowed to graze the clones and grazing preference was determined visually. Prior to the grazing, multiple morphological and chemical parameters were measured. Parameters that were correlated with sheep preference were digestibility (r = 0.86), water soluble carbohydrate content (r = 0.74) crude fi ber content (r = −0.67), leaf blade width (r = 0.57) and sward height (r = −0.53)
Silica content, leaf softness and digestibility in tall fescue (Festuca arundinacea Schreb.)
No full textIn tall fescue breeding, a great deal of effort is devoted to develop soft-leaved varieties as it is generally accepted that leaf softness is positively correlated with digestibility and animal preference. In advanced breeding programs, it becomes difficult to discriminate the leaf softness between genotypes. Moreover, there is evidence that the digestibility of the softest varieties is not necessarily higher compared to varieties with coarser leaves. We studied the presence of trichomes (dentation) on the leaf margins and the silica content of plants in relation to the leaf softness and digestibility on a selection of 19 tall fescue clones. On average, soft genotypes had fewer trichomes (2.74 mm −1 ) on the leaf margins than coarse genotypes (9.03 mm −1 ), but there was no relation between leaf softness or trichome number and digestibility (R 2 = 0.05), nor between silica content and softness or digestibility (R 2 = 0.09)
Yield comparison of Italian ryegrass and winter rye sown as cover crops after forage maize
No full textHedysarum coronarium L. : variation génétique, création variétale et utilisation des rotations tunisiennes / par F. Ben Jeddi.
Full text linkPotential in mixed swards and breeding of tall fescue (Festuca arundinacea Schreb.)
Full text linkThe incentives of this thesis are some of the challenges that grassland production in Belgium are exposed to. First, more dry summer spells are predicted due to climate change (IPPC, 2007). Second, more grass is cut and conserved due to current trends in dairy production. Tall fescue (Festuca arundinacea Schreb.; Fa) is a forage grass species that is expected to cope with these challenges.
This thesis had three objectives:
1. to study the agronomy of Fa under Belgian conditions;
2. to develop methods that could be used in breeding to overcome the main disadvatages of Fa;
3. to breed an Fa Variety adapted to Belgian circumstances
Modelling the nitrogen surplus and the efficiency of nitrogen use in Flemish dairy farms
Full text linkIn Flemish dairy farms it is very important to decrease the nitrogen surplus and to improve the efficiency of nitrogen use in Flemish dairy farms. This research developed models based on multiple regression in order to have an insight in the nitrogen surplus and the efficiency of nitrogen use in Flemish dairy farms. The dataset used comprised 1511 records from the Farm Accountancy Data Network (FADN) of Flanders. The monitoring period ran from 1989 to 2001. Different methods were used to find the best regression equation: ‘substantive knowledge’ methods (both ascendant and descendant), ‘stepwise’ methods and the ‘best-subsets’ methods. Many models were developed and tested. The main criterion to select a final model was the presence of relevant variables as known from literature. On top of this, models were preferred if the estimators of the regression coefficients were unbiased, if the degree of multicollinearity was low, and if there were no significant interaction terms. Unstandardized and standardized regression coefficients were calculated in order to clarify the relative importance of each independent variable. Finally, one model was selected for the nitrogen surplus and two models for the efficiency of nitrogen use. The two models of the efficiency of nitrogen use were developed with a dataset of records of farms with and without arable crops. The final models recommend similar actions in order to decrease the nitrogen surplus and to improve the efficiency of nitrogen use. These models show that decreasing the nitrogen in fertilizers and concentrates has the strongest potential to decrease the nitrogen surplus. The interpretation also reveals that both extensive and intensive dairy farms can produce in a clean way. There was a negative correlation between the livestock units of dairy cows per hectare and the nitrogen surplus in this dataset. Supported by data from the literature (Kebreab et al. 2001) it could be proven that this relationship was correct
Morphological and cytogenetic study of ornamental Ranunculaceae to obtain intergeneric crosses
No full textTransgenic crops : a kaleidoscopic impact analysis
Full text linkIn this interdisciplinary PhD thesis, a kaleidoscopic perspective on the impact of genetically modified (GM) crops and their corresponding agro-food products was presented. By placing some of the impacts resulting from the adoption of the novel agricultural technology in a socio-ethical, legal (part I) and agro-ecological context (part II), light was thrown upon different dimensions of agro-food biotechnology. The agro-ecological part, which is structured around three pertinent case studies, focused on the processes of vertical gene flow and herbicide usage. Based on the facets studied, it was observed that the concept of sustainability has come to occupy a prominent place in the debate about agro-food biotechnology. Therefore, it was investigated whether the adoption of agro-food biotechnology might play a role in constructing a sustainable system of crop production (part III)
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