Return On Investment With Phosphorus Supplementation

You may have heard the Field Advisors from AgSolutions talk about using “the right product for the right time” and when you have livestock grazing phosphorus (P) deficient country the best time to target P supplementation is when there is green grass available. This is because P supplementation works best when pasture quantity and quality is high and protein and energy are no longer the most limiting nutrients.

Despite much of northern Australia being deficient, to acutely deficient, in phosphorus not many graziers are investing in targeting P supplementation during the wet or green season. Is this because they are still not convinced that the returns outweigh the cost despite the many scientific trials that have shown that feeding P supplements to growing animals results in increased liveweight gains?

This MLA funded trial showed that adequate phosphorus levels resulted in steers gaining 125kg more than steers with a phosphorus deficient diet.

This gain of 125kg occurred over a 5-month period. In today’s market that’s an increase of approximately $440 per head.

If these potential liveweight gains in growing stock are not enough to sway you to the benefits of supplementing with extra phosphorus when required, then what about the exciting new results from ongoing trial work into P supplementation of breeding cattle on P deficient soils. The trial being conducted at Kidman Springs (Victoria River Research Station) involves 179 cattle split into two treatment groups that have been managed in exactly the same way since weaning except one group is supplemented with mineral loose lick containing 9% P (P group) while the other group didn’t get the additional P in the supplement. The cattle graze adjoining paddocks of native pasture that are acutely phosphorus deficient and the loose lick is fed to them all year.

Source: MLA funded University of Queensland Trial 2012, Update of Phosphorus project NBP537; pen study conducted by D Poppi & S Quigley, 13 March 2012, University of Qld)

Interim results are really positive for the cattle that have access to the phosphorus supplement resulting in:

  • Maiden heifers in the P group were 66kg heavier at the end of the first mating as two-year olds,
  • P group heifers had a 10% high pregnancy rate,
  • P group heifers had a 25% higher re-conception rate,
  • First lactation heifers in the P group averaged 120kg higher when their calves were weaned,
  • P group cattle produced calves that were 34kg heavier at weaning,
  • The overall mortality rate in the P group from weaning to 3.5 years was 7% lower.

In addition, in 2018 the group supplemented with P (90 head) weaned an additional 13 calves (43 as compared to 30) and produced 2.8 tonnes more of weaned calves than the group without P supplements (there were not only more calves, but the calves actually weighed heavier as well). If these calves were valued at $3/kg, this would equate to $8,400 extra compared to the untreated group (or in other words, an additional $93 per head based on the original 90 animals in the P group).

But what does phosphorus supplementation cost? To use MegaMin Extra Phos 8 as an example, you can provide a quality source of phosphorus (and other important macro and trace minerals) for around 15c/head/day or just under $55/head/year (when fed year-round). While MegaMin supplements weren’t used in this particular trial, and bearing in mind that different responses will be achieved for different levels of phosphorus deficiency, you can see the potential of a great return on investment from phosphorus supplementation.

Hopefully, the positive results coming out of the ongoing research into the use of phosphorus supplements will give graziers the confidence to invest in supplementation programs during the green/wet seasons if they have stock grazing P deficient country.

If you need help determining whether your livestock could benefit from additional P in their diet, AgSolutions can assist you with testing your soil, as a reading below 10ppm Colwell P on a soil analysis generally indicates that a response may be achieved with phosphorus supplements.

For more information please contact AgSolutions or ask at your preferred rural store for MegaMin Extra Phos 8.

By Shannon Godwin (BAppSC GDTL)

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Jackson, D., Rolfe, J., English, B., Holmes, B., Matthews, R., Dixon, R., . . . MacDonald, N. (2012). Phosphorus management of beef cattle in northern Australia. Sydney: Meat & Livestock Australia Limited.

Meat & Livestock Australia. (2016, November 4). New phosphorus findings. Retrieved from MLA:

Poppi, S. Q. (2013). Re-alimentation of phosphorus deficient cattle. North Sydney: Meat & Livestock Australia Limited.

Schatz, T. (2018, December 5). Kidman Springs Phosphorus Supplementation Project. Retrieved from Future Beef:

Schatz, T. (2018, December 5). New research on the benefits of phosphorus supplementation from Northern Territory Department of Primary Industry and Resources trial. Retrieved from Northern Territory Government Department of Primary Industry and Resources: