New feed mixtures for organic sows aim to reduce their phosphorus emissions to the environment
Organic sows excrete much more phosphorus than conventional sows. This is partly because their roughage intake is not considered when formulating their feed. A new project funded by GUDP will address this.
They trot around and grunt comfortably outside the huts, rooting in the ground.
Around them, the piglets run around and play. When they are hungry, they go to the trough to eat. When they need to relieve themselves, they do so somewhere in the enclosed field.
The organic sows appear to have a good life, but their welfare comes at a price.
They are getting enough, and perhaps too much.
Organic sows excrete 43% more phosphorus than conventional sows. This currently puts pressure on organic farmers.
A new phosphorus regulation increases the area requirement for organic sows unless the farmer can document measures that reduce their emissions. One reason for the higher phosphorus excretion from organic sows is that the synthetic enzyme phytase cannot be used in the feed. Phytase makes the phosphorus naturally present in the feed more accessible, allowing for better absorption by the pigs and resulting in less excretion in their manure.
Since organic sows cannot be fed with phytase, additional phosphorus is added to their feed to ensure their nutritional needs are met.
Another reason is that roughage, which organic pigs must be offered in addition to their concentrate feed, also contributes to their mineral intake. However, this is not accounted for when the concentrate feed is made because the nutritional value of the roughage is largely unknown.
The nutritional value of roughage will be determined
One of the elements of the new project is to investigate how much phosphorus roughage contributes to a diet for pregnant sows, and, importantly, how well it is utilized.
The study will include fresh grass that sows will eat in the summer, as well as grass silage and grass-pulp produced through the biorefining of grass. The latter are roughage sources for feeding during the winter. Manure, blood, and urine will be analyzed for phosphorus content, vitamins, and other minerals.
"When we have this extensive study, it would be foolish not to analyze for other micronutrients than phosphorus, as very little is known about them," says Associate Professor Tina Skau Nielsen, who leads the project.
"It is plausible that other minerals than phosphorus could be adjusted in the future."
Reducing phosphorus content in concentrate feed
If roughage can contribute to the sows' mineral supply, there is a potential to reduce the amount of added phosphorus in their concentrate feed.
However, this mustn't compromise the health and longevity of the sows. Therefore, the project also includes a study where sows are fed a concentrate feed with reduced phosphorus content together with their supply of roughage. This will examine how the reduced content affects the sows’ condition and nutrient status.
It is also crucial that the piglets are not negatively affected by the sow's feed, which will also be investigated.
It must work in practice
"One of the challenges in organic pig production is that the individual animals' intake and ability to utilize roughage can vary greatly," explains Tina Skau Nielsen.
"Therefore, there must be a sufficiently large safety margin to ensure the animals meet their needs."
Conditions at the university's eco-platform differ in some ways from commercial farms, but this is where it must work. Therefore, commercial feed mixtures are being developed to be tested in practice. It is also here that researchers will examine the effects on the environment.
The impact on the soil
It is well known that nitrogen is unevenly distributed in the pastures of organic pigs, but such knowledge does not exist for phosphorus.
The project will therefore describe how phosphorus is distributed on the pasture soil and within different soil layers. This will be done before and after feeding concentrates with a reduced phosphorus content.
This is a significant foundation for developing new strategies to optimize phosphorus balance and reduce losses of phosphorus in the soil.
Perspectives for farmers and the environment.
The project started in December 2024 and is set to end in November 2028.
Results will be communicated continuously to the project’s stakeholders, primarily Danish organic pig farmers. Moreover, the project provides a solid scientific foundation for understanding the dynamics of utilizing the planet's limited resources, benefiting both the environment and the farmers' economy.
Additional information | |
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External funding | Danish Agriculture Agency, Green Development and Demonstration Programme (GUDP) |
External collaborators | Aarhus University, Department of Agroecology Innovation centre for Organic Farming Krarup Farm I/S Vestjyllands Andel |
External commenting | None |
Conflicts of interest | None |
Read more | Forbedret fosforudnyttelse hos økologiske søer (FORFOS) - Aarhus Universitet |
Contact information | TinaS.Nielsen@anivet.au.dk |