SWE
Our thoughts about Ca/P ratios
Phosphorus (P) is an important mineral for the construction of the skeleton and for energy metabolism in cells. An excess can lead to osteoporosis and many other problems, as well as negative impacts on our environment. Phosphorus is not lacking in good soils where the organic material and humus layer are balanced. Maintenance requirements are based on an estimated loss through feces and urine of about 1 g/100 kg of weight per day. The need increases slightly with higher work intensity.
Why does Activ Mineral contain so little phosphorus?
In this article, we will discuss our approach to phosphorus and the Ca/P ratio. We find that many horse owners focus only on the value of phosphorus and the ratio in the individual feed supplement, without considering the whole picture. We do not want to contribute to unnecessary phosphorus eutrophication that has a negative impact on the climate. Giving horses more phosphorus than they need results in the horses excreting it in their feces, which then spreads on our fields and pastures and can contribute even more to the existing phosphorus surplus. In Sweden, there are more horses than dairy cows, and how we feed and keep our horses affects the climate. To reduce nutrient leakage, agriculture is allowed to add a maximum of 22 kg of phosphorus per hectare, but there is currently no legal regulation regarding phosphorus coming from horse pastures. Research has shown that an average of 60 kg of phosphorus per hectare can be added in horse pastures, which is three times as much as is allowed in agriculture. Leakage from agriculture depends on several factors, and only some of them can be influenced. What is grown and how it is fertilized, as well as the direction of production and how animals are fed, can affect these factors. By reducing nutrient leakage, and thereby the risk of eutrophication, the burden on the climate is often also reduced. When the leakage of plant nutrients to lakes and oceans decreases, it usually means that greenhouse gas emissions also decrease. Let's now look at the horse's need for phosphorus.
The Need for Phosphorus (P)
According to the Swedish University of Agricultural Sciences (SLU), the need for an adult horse - maintenance is 2.8 grams per 100 kg body weight.
- Horse 500 kg - 14 grams An adult horse (500 kg) in work with a maintenance need of 56 MJ and a work supplement of 22 MJ (40% of maintenance) needs at least: 21 grams An adult horse (500 kg) in work with a maintenance need of 56 MJ and a work supplement of 75-130% needs at least: 29 grams
Phosphorus Content Average Various Sources
- Roughage - Large variation in different parts of Sweden, average calculated at 2 grams/kg, always take a roughage analysis
- Wheat bran, oats, barley, and compound feeds - average 5-8 grams/kg
- Alfalfa - 3 grams/kg
- Supplements - Review all supplements the horse receives, e.g., some magnesium supplements also contain phosphorus. The content in Activ Mineral is 300 mg/kg - Other brands often up to 40 grams/kg.
- Pasture - Horses grazing also ingest phosphorus from the grass, intake here is harder to measure.
What is the total intake and ratio for the entire diet?
Calculate your horse's phosphorus intake from all sources and see what value you get. How do you compare to the need? When it comes to the ratio, a suitable range for the Ca/P ratio is 1.2-1.8, but if the forage is rich in Ca, the ratio may be higher. In feeding trials, Ca/P ratios up to 6 have been used without observing any negative consequences on the horses. However, the condition is that the P-need is met.
Is Phosphorus Deficiency Common?
Pat Coleby, a feed expert, says: Phosphorus deficiency is rare. Even when levels are extremely low, animals do not seem to suffer from it, provided they have access to the minerals they need, either as supplements or in the feed. Since the mid-1990s, soil analyses have shown phosphorus reserves, and the figures are striking. Some dairy farms where available phosphorus is about half to three-quarters of what it should be - 10-15 ppm instead of 20 - have reserves of 500 to 2800 ppm. This locked phosphorus will become available when the levels of magnesium and calcium in the soil are corrected.
Are you still unsure? Too much or too little?
To check what the horse actually absorbs and processes the nutrition we give them, it is recommended to periodically perform blood tests for mineral status on the horse.
To check phosphorus, a feces test can also be taken, which is simple to do and is also a good indicator, unlike urine tests where the excretion of phosphorus can only be read if overfeeding occurs by at least 300 percent. Fecal tests are also an effective method for horses on pasture or that have free access to feed. The sample is taken from multiple piles and then sent to a feed lab for analysis. To get a more accurate result from an individual horse, the fecal sample should be taken on multiple occasions. If the concentration of phosphorus in the feces exceeds 8 g/kg dry matter in adult horses, it is likely that overfeeding is occurring. Tests can be ordered from Agrilab (Fertilizer Analysis) and Eurofins (delivery note Natural Fertilizer & Compost).
Learn More About Phosphorus
The University of Gothenburg, DEPARTMENT OF BIOLOGY AND ENVIRONMENTAL SCIENCE, published the study PHOSPHORUS LEAKAGE FROM HORSE PADDOCKS, summary:
This study investigated phosphorus leakage from horse paddocks. The number of horses has increased in Sweden, and there are now more horses than dairy cows in the country. To reduce nutrient leakage, agriculture is permitted to add a maximum of 22 kg of phosphorus per hectare, but there is currently no legislation regulating phosphorus from horse paddocks. Research has shown that on average 60 kg of phosphorus per hectare can be added in horse paddocks, which is three times the amount allowed in agriculture. A literature review was conducted to find answers to whether phosphorus leakage is greater from horse paddocks than from agricultural land and whether the type of soil and the number of horses per hectare affect the leakage. A survey aimed at riding schools in Sweden was also conducted to find out which of a number of proposed phosphorus-reducing measures were possible for riding schools to implement. Riding schools were also asked about how they would be affected by possible legislation regulating the number of horses per hectare. The results of the literature review showed that phosphorus leakage is greater from horse paddocks than from agricultural land. The type of soil also matters for the leakage, where clay soil leaks more than sandy soil. The number of horses per hectare also matters, where more horses per hectare generate greater phosphorus leakage. The survey showed that many riding schools have already implemented several measures, but it also emerged that the lack of financial resources was the most common factor preventing measures from being implemented. A lack of knowledge about how some of the measures worked and whether they were beneficial for the riding school was also revealed. Legislating to limit the number of horses per hectare is not a good option, as several riding schools would have to close their operations due to a lack of land. Instead, it is better to focus on increasing riding schools' knowledge about different measures and providing financial support to implement such measures.
Read it in full here: Phosphorus Leakage from Horse Paddocks Study
The Swedish Board of Agriculture explains eutrophication
Agricultural land contains large amounts of nitrogen and phosphorus. When the soil is disturbed during cultivation, such as when plowing, harrowing, and sowing, more of these nutrients are released. Fertilization then adds more nitrogen and phosphorus.
When water moves through the soil, or runs on the surface, some of the plant nutrients come along. Most are taken up by the crops, but some end up below the root depth where they cannot be reached by plant roots. Instead, the plant nutrients are carried further to groundwater, ditches, and watercourses and eventually end up in lakes and seas. It is a contributing cause of eutrophication and the Baltic Sea's algal blooms.
Leakage of nutrients from the soil is natural, but the cultivation of the land increases the leakage. When agriculture was mechanized, and mineral fertilizers began to be used, the intensity of cultivation increased, and so did the leakage of nitrogen and phosphorus.
Leakage from agriculture depends on several factors, and only some of them can be influenced. What is grown and how it is fertilized, as well as the direction of production (feeding, plants or animals), can affect these factors.
Measures that reduce the leakage of nutrients, and thereby the risk of eutrophication, often also reduce the burden on the climate. When the leakage of nutrients to lakes and seas decreases, it usually means that emissions of greenhouse gases also decrease.
Learn more: Agricultural Nutrient Leakage and Eutrophication
Pat Coleby's experiences with Phosphorus
In Australia, artificial phosphorus, such as in superphosphate or other phosphate fertilizers, was originally a substitute for barnyard manure. In Europe, animals were brought indoors for the winter, and the manure was spread on the fields for the next harvest. In autumn, lime was applied to maintain the balance in the soil because the phosphorus from organic material could not be fully utilized without lime. The result has been an excess of superphosphate or phosphorus that has locked up a whole range of minerals, including magnesium, sulfur, copper, selenium, cobalt, boron, zinc, and probably manganese and molybdenum, and phosphorus itself. Soil analyses done today show that there is a supply of unavailable phosphorus in all cases I have seen. That these minerals and trace elements have become unavailable has caused significant harm to animal health. The lack of magnesium and copper is probably the worst. The sections on these two minerals show the price we pay for our overuse of phosphate fertilizer without thinking about the limestone minerals. Phosphorus is necessary for healthy growth. It should be kept in balance with calcium and magnesium. An excess of phosphorus will lead to osteoporosis and many other problems of the sort associated with magnesium deficiencies. Phosphorus will not be lacking in healthy, well-managed soils with plenty of organic material and humus. Soils from which large crops have been taken without anything being returned to the soil will eventually lack organic material and phosphorus.
Sources: SLU Feeding Recommendations for Horses
Fecal Analysis - A Good Marker for Overfeeding with Phosphorus
Jordbruksverket Nutrient Leakage and Eutrophication
University of Gothenburg DEPARTMENT OF BIOLOGY AND ENVIRONMENTAL SCIENCE study PHOSPHORUS LEAKAGE FROM HORSE PADDOCKS
Natural Farming, Pat Coleby
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