Winter vetch as preceding crop to maize and as silage for pigs

Background and Objective

The aim of the planned project is to evaluate different winter vetch species for arable farming and feeding as a whole plant in Northern Germany.
There is a wide range of different species of vetches, which grow as cultivated and wild plants worldwide under different conditions and can be found both as a valuable crop rotation element in pure seed and in mixtures and as a component of grassland. They are used as green manure, for obtaining the seeds as fodder or food, as hay, silage or pasture, and also as a whole plant in the feeding of various types of livestock. Vetches have a high arable value due to, among other things, the possibility of nitrogen fixation and the good rooting ability. They are good preceding crops and catch crops and are able to increase biodiversity. Therefore they are not only of interest in organic farming. The use of winter vetches as a winter catch crop with use as green manure or fodder is attractive from an agronomic point of view because the location requirements of the vetch are low, the soil cover over winter protects the field from erosion and the N2 fixation of winter vetches can significantly improve the preceding crop value. With the integration of leguminous winter catch crops into the crop rotation an optimization of the crop rotation can be achieved. The nitrogen fixed by leguminous winter catch crops can already be reused to a high degree by the following crop. At the same time, the danger of nitrogen being displaced into the groundwater is avoided, as the succeeding crops can absorb the released nitrogen very well. In addition, the establishment of winter catch crops is usually very successful. After the harvest of the main crop, a sufficient margin remains for soil cultivation and the resulting later date of cultivation ensures a good water supply, so that winter catch crops can be established much better than summer catch crops grown as stubble crops. On the other hand, since the legume winter catch crops provide additional forage area, the cultivation period could be reduced from a perennial to an over-year clover-grass cultivation. Thus, a legume preceding crop can be cultivated several times in the crop rotation, from which the subsequent crop benefits. In such a cultivation system, the overall N utilization in the entire crop rotation can be increased.
Due to their high protein content, vetches are not only interesting as seeds for feeding livestock, but also as a whole plant they provide a lot of crude protein. The negative effects of feeding the seeds to monogastric animals, which result from the antinutritive ingredients (ANF), could take a back seat when using the whole plant, as these are primarily localized in the seeds. In addition, silage of whole winter vetch plants could reduce possibly existing ANF. The use of whole plant products from vetches can therefore contribute to improving the protein supply of monogastric farm animals. However, both the protein quality (amino acid composition and digestibility) and the secondary plant constituents must be considered in order to assess the value of these feeds in feeding. Another advantage of using vetches as a whole plant is the expected increased riboflavin content. Since riboflavin is in short supply in most cereal-based rations for monogastric animals and green growths of legumes are known to have high riboflavin contents, it should be examined whether green cuttings or silages from different types of vetches can contribute to the riboflavin supply of monogastric farm animals.
In the planned project varieties of different winter vetch species will be tested for their suitability for cultivation in Northern Germany, their previous crop effect in maize and their suitability as high-protein, riboflavin-supplying feed. For this purpose, cultivation trials will be carried out, resulting in recommendations on varieties and cutting times with regard to the use of the whole plant as feed for monogastric animals. Analyses of the feed value (valuable and antinutritive ingredients, energy and digestibility) of the whole plant as green cut and silage also contribute to these recommendations. Feeding trials with fattening pigs are also used to test acceptance and achievable animal performance.

Approach

In a three-year field trial, the Thuenen Institute will investigate the effect of different winter vetch species and varieties in pure stand and in a mixture with cereals on the yield of maize. In a further test, winter vetches in pure stand will be used to determine how the contents of valuable and antinutritive ingredients in winter vetches change in the course of growth. At the same time, laboratory-scale studies to test the ensiling capacity of the whole plant will be conducted. In an acceptance test in the first year and a performance test in the second and third year the suitability of the silages in fattening pig feeding is tested at the Thünen-Institute. In addition, the precaecal digestibility of the nutrients in the winter vetch silages is determined at the Martin-Luther-University Halle-Wittenberg in fattening pigs.  Analyses of the feed value (valuable and antinutritive ingredients, energy and digestibility) of the whole plant as green cuttings and silage will contribute to derive recommendations for the use as feed for monogastric animals.