Whole Crop Wheat and Barley Silage in Dairy Production

The main objective of the project has been to establish a knowledge platform for producing high yields of whole crop wheat and barley silage with appropriate nutritive value for dairy cows under Norwegian conditions. Whole crop is cereals and/or annual legumes in which stems, leaves and grain are harvested together, ensiled and fed to ruminants. Whole crops are supposed to contribute with a high yielding, single cut containing both starch and fibre (and eventually protein) which will improve feed utilization, feed intake and animal production when supplemented to early harvested, low fibre grass silage. The interest in production and utilization of whole crop silage has been increasing in Norway. However, many farmers have experienced disappointing low yields as well as low starch contents in their whole crop silages. There have also been concerns about whether dairy cows are capable to utilize the starch from late harvested whole crop cereals without processing (?cracking?). This project aimed to give answers to some of these questions and challenges. In order to obtain a high starch containing whole crop, the research has revealed that both barley and wheat must reach medium dough stage. However, the relation between stage of development and starch content is not consistent, but depends on the ratio between spikes and straw. This, in turn varies between species, growing conditions and nutrient availability. Higher starch contents were revealed in barley compared to wheat at corresponding stages of development. It has been demonstrated that it is possible to produce well preserved, big bale whole crop silage without comprehensive losses of grain and starch throughout the harvesting and baling process when harvested at medium to hard dough stage. However, it may well be that the risk of losses increases at delayed harvest and with intercropping legumes and cereals. Processing should be avoided in order to reduce harvesting losses. It has been revealed that processing (cutting, chopping) and use of compactor-balers not necessarily improve the fermentation quality and nutritive value of baled whole crop silage, despite the fact that processing and compactor balers ensures improved density of the bales. Moreover, it has been revealed that cracking may lead to significant losses of starch during the fermentation process. Full understanding of the mechanisms behind these losses has not been achieved. Part of the explanation may be that cracking exposes the starch to hydrolyses, facilitated by drop in pH by consequence of initial microbial fermentation of sugars. Finally, research in this project has documented that the starch in whole crop wheat silage, harvested within the dough stage, is nearly 100% digested without kernel processing. However, this result do not imply that later harvested whole crop silage need to be processed. As the digestibility of the fibre fraction clearly decreases and that dry matter yield is not improved, the motivation of postponing the harvest after having reached mid to late dough is absent. When harvesting before passing the dough stage, harvesting machinery available for most Norwegian farmers, i.e. mowers and big balers, may be used for producing whole crop silage. Despite the fact that losses of starch may occur during harvest and fermentation, early harvesting (prior to dough stage) is likely to be the major cause of low starch contents in baled whole silage produced by many Norwegian farmers.

The interest in and usage of Whole Crop Silage (WCS) as feed for dairy cattle has been increasing, both in Norway and in other Northern European countries. Whole crops usually return high yields from one single cut and may contribute significant amounts of starch as well as fibre, and reduce the need of purchased feeds. However, many farmers have not obtained the targeted starch content in their WCS, and feeding experiments have so far demonstrated that increased DM intake when WCS is offered is not allways accompanied by increases in milk production. In this project, field experiments will be conducted in order to investigate whether low starch contents in WCS may be due to crop composition and structure and/or losses of kernels during harvest and baling. In cooperation with manufacturers and sellers of mowers and balers, low-cost modifications of the machinery that will prevent losses and ensure the necessary pre-ensiling processing, will be sought developed and compared with preservation of less processed WCS added an acid containing preservative. A digestibility trial with dairy cows will be conducted to investigate whether processing of late harvested WCS is crucial to avoid that the kernels passes undigested throughout the digestive tract. Finally, a small scale ensiling trial will be conducted to investigate whether pre-preservation kernel crushing have impact on starch contents in WCS. The final aim is to develop a knowledge platform for producing and processing high yields of WCS with appropriate nutritive value for dairy cows, and to deliver new data to NorFor for better prediction of the nutritive value and role of WCS in dairy (and beef) production. . The project has its foundation in questions and ideas raised by farmers and the extension service, and the involvement of stakeholders at several stages will ensure an efficient and continuous flow of information into and out of the project.