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Phosphorous is the most expensive element to feed to cattle so wouldn’t it make sense to ensure you get your dollar return on what you supplement to your herd? While the requirements for P for growing bones, milk production and lactation are well understood, what is less understood is the requirement for P by rumen microbes to promote rumen fermentation and the difference sources of P that can be utilised to effectively feed P to cattle. In this post, we will explore the difference between feeding urea phosphate, di-calcium phosphate, and mono di-calcium phosphate as a phosphorous source. 

Phosphorous deficiency is prevalent across nearly all Australian soils and it is well understood that phosphorous supplementation, particularly in the wet & growing season can provide beneficial results as it is the first limiting nutrient during these periods. FutureBeef1 reports that the major impact of phosphorous deficiency is a significant decrease in appetite, resulting in a reduction of pasture intake which in turns means less energy and protein intake. Phosphorous can be fed in several forms including loose licks, liquid supplements, blocks or via water supplementation.

The primary source of phosphorous in supplements in Australia include-

  • Di-calcium phosphate (DCP)  
  • Mono do-calcium phosphate (MDCP)  
  • Kynofos (A blend of MCP and DCP)  
  • Phosphoric Acid  
  • Urea phosphate  

All sources provide an ideal source of phosphorous in supplementation programs for livestock, and what it is generally understood and accepted by the industry is the importance of balancing the calcium and phosphorous ratio. DCP and MDCP are calcium-phosphorous blends that supply calcium at the same time as supplying phosphorus. However, what is often overlooked is that calcium deficiency is rarely an issue in Australia and nearly all grazing livestock will obtain calcium requirements directly from their pasture intake. In extreme cases, the supplementary feeding of calcium with phosphorus on top of the available calcium obtained from pasture can throw the C:P balance out! In the majority of cases though, supplementary feeding of calcium in conjunction with phosphorus provides no additional production benefit.   

Urea phosphate is a patented DIT supplement, able to be dosed into the livestock drinking water via the Nutridose or uDOSE. Urea phosphate provides a 100% soluble source of phosphorous whilst at the same time providing an additional source of nitrogen rather than calcium.  There are a number of studies that have demonstrated the production benefits that come with feeding small amounts of non-protein nitrogen during the wet/growing season. Additionally, providing a source of non-protein nitrogren to livestock provides a very reliable buffer against sudden pasture protein drop experienced at the start of the dry season. All of this translates to more kilos of production and more weaners on the ground.  The main benefits of urea phosphate include-

  • 100% soluble and available source of phosphorous  
  • Provides a slow release source of nitrogen  
  • Highly soluble in water so very suited to water supplementation  
  • Highly acidic compound (pH 2) so can be used to buffer urea against the alkalinity of Australian bore waters  

Whilst there are several phosphorous compounds available on the market, graziers need to ensure they maximise their return on investment and minimise supplementation costs. It is possible to measure the gap in phosphorous and nitrogen requirements by doing a faecal analysis whilst calcium requires bloods to be taken. However, what is fundamentally important to consider is the role of supplementary calcium when calcium is seldom a limiting nutrient and the cost benefit of this when compared to other phosphorus sources.