Traditionally, grain is stored with a water content of around 14 percent. With such a low water content the grain can be stored under normal conditions without turning mouldy or rotten. However, when it rains day after day during the harvest season, as has been the case in many areas in Denmark this year, it can be a somewhat difficult task for the farmer to harvest and store his grain with a sufficiently low water content. An alternative could be to store the grain under airtight conditions.
Scientists from Aarhus University have collaborated with the silo manufacturer Assentoft Silo A/S to investigate how airtight storage affects the pig’s digestibility of various grain nutrients.
– We expected that airtight storage of the grain would have a beneficial effect on its nutrient value as a feed and we were proven to be right, says head of research unit Hanne Damgaard Poulsen from Aarhus University.
When the pigs utilise the phosphorus and protein from the grain better it also has a beneficial effect on the environment. Instead of the surplus, non-digested nutrients ending up in the manure and, at the end of the day, in the environment, they are metabolised and used by the pig.
Airtight grain for pigs
The scientists used wheat and barley in their studies. Half of the grain was harvested and stored with a low water content while the other half was harvested and stored with a somewhat higher water content under airtight conditions. All portions were stored for about six months. Two groups of finishers were fed for 12 days with a feed containing either airtight grain or regular grain. The feed containing the airtight grain had a water content that was approximately three percent higher than the feed containing the dried grain.
Some of the phosphorus in grain is bound in a complex called phytate, which greatly reduces its availability to the pig. The enzyme phytase metabolises the phosphate-rich complex phytate during storage. The content of phytate-bound phosphorus in the airtight grain decreased approximately seven percent in the course of the half year that the grain was stored.
– This means that during the low-oxygen storage period there was a release of phosphorus from phytate, explains Hanne Damgaard Poulsen. The analyses also showed that airtight storage of grain protects phytase activity. These two conditions led to a rise in phosphorus digestibility from 41 percent to 46 percent as a result of the low-oxygen storage.
Correspondingly, protein digestibility increased from 78.2 to 80.7 percent in the airtight grain. This is important with regard to how much surplus nitrogen risks being emitted to the environment. The more of the protein that the pig can utilise, the less nitrogen ends up in the environment.
The digestibility of phosphorus and protein is higher in airtight stored grain than in traditionally stored grain, according to studies at Aarhus University.
For more information please contact: Head of research unit Hanne Damgaard Poulsen, Department of Animal Science, telephone: (+45) 8715 7895 email: HanneDamgaard.Poulsen@agrsci.dk
Source: Aarhus University