Easy P trial update

Key messages:

  • Preliminary results show that heifers perform just as well, if not better under the Easy P treatment, when phosphorus is included in dry season lick, as well as having access to bulk bags of phosphorus lick over the wet season.
  • The “Easy P” phosphorus supplementation strategy could be a solution to addressing phosphorus deficiencies in country where paddock access is difficult during the wet season.

The recently completed Kidman Springs phosphorus (P) trial showed large benefits and a very high return on investment from feeding phosphorus supplement to cattle in phosphorus deficient country. However, some properties don’t do it because it is too difficult to feed out during the wet season, due to flooded creeks and boggy roads. This trial was designed to address these issues by developing a strategy of phosphorus supplementation that is easy to implement.

The Easy P strategy

The Easy P strategy includes adding phosphorus into dry season supplement, and putting out enough bulk phosphorus supplement before the start of the wet season.

This trial is being conducted at Kidman Springs, using the same paddocks as the previous phosphorus trial. In this trial, we’ll determine whether the Easy P strategy is as effective as traditional wet season phosphorus supplementation by comparing the strategies, side-by-side.

If the Easy P strategy proves to be as effective, it would be ideal for properties with limited wet season paddock access.

Supporting evidence

Including phosphorus in dry season supplementation is being trialled due to previous trial results. During the original Kidman phosphorus trial, the phosphorus supplemented animals performed much better than the animals without phosphorus supplementation despite the fact that they didn’t achieve their target phosphorus intake during the wet season. Therefore, it seems likely that there were benefits from including phosphorus in their dry season supplementation program.

Also, we know that phosphorus is not stationary in the body; rather, cows mobilise it from their bones and tissues if there is not sufficient phosphorus in their diet. In northern Australia, this commonly occurs when cows are lactating, as there is a lot of phosphorus in milk. As a result many cows have low phosphorus stores by the time they finish lactating when their calves are weaned. Therefore there are likely to be benefits from supplying phosphorus supplement to cows in the dry season after their calves have been weaned, to replenish their phosphorus stores which were depleted during lactation.

Trial design

The Easy P trial started in mid 2020 with 181 x 18 month old Brahman maiden heifers. These heifers were mated for the first time in late December 2020. They were randomly allocated to either the Easy P (EP) or Traditional supplementation (TS) treatments, to give two groups of similar number (EP = 90, TS = 91) and average weight (EP = 271 kg, TS = 266 kg).

The treatments are managed in the same way except for the supplement provided. The Easy P group have phosphorus in their dry season supplement while the Traditional group do not (Table 1). Both groups receive the same wet season supplement, except the Easy P supplement is delivered in bulk before the start of the wet season. The heifers in the Easy P treatment group are provided two one tonne bags with the top cut off. Whereas, the Traditional supplement is delivered weekly throughout the wet season (25 kg bags delivered to covered troughs). The amount of supplement delivered to the Easy P paddock (before the wet season starts) is calculated based on supplying each cow with at least 9 g of phosphorus per head, per day, throughout the wet season. In the supplement mix described in Table 1, that would be 100 g of supplement per head, per day, as it contains 9.7% of actual phosphorus.

The supplement is fed ad libitum to the Traditional group throughout the wet season as required with bags delivered weekly.

Table 1. The supplement contents for the Easy P and Traditional treatments during the dry season and the wet season.


*The phosphorus source is a high quality MCP (Total P = 22.7%, TAC Value = 85%). We gratefully acknowledge the sponsorship of Causeway Beef Nutrition for supplying the supplement.

Preliminary results

The trial has been running for two years now, and some preliminary results are available.

After the first year (post maiden mating muster, May 2021) there was no significant differences between treatments for annual growth.  The Easy P cows grew 109.3 kg on average, whereas the Traditionally supplemented cows averaged 113.9 kg of growth. Pregnancy rates were also similar (EP = 95.5%, TS = 94.5%).

The heifers calved for the first time over the 2021/22 season, with the calves being weaned in May. Year two’s summarised results can be seen in Table 2, however statistical analyses have not yet been conducted.

Easy P strategyTraditional supplementation
Year 1: Post maiden mating muster, May 2021
Annual growth109.3 kg113.9 kg
Pregnancy rate95.5%94.5%
Calves born during 2021/2022 wet season, weaned May 2022.
Year 2: Weaning muster, May 2022
Calf loss from pregnancy test in 2021 to weaning in 202216%13%
Pregnancy rate 84%70%
Cow average weight 397 kg376 kg
Weaned calves average weight185.8 kg179.1 kg

While it is not possible to say at this stage whether these differences are significant (statistical analyses to come), we can say that the Easy P treatment is performing as well as, or better than, the Traditional supplementation treatment. Therefore, the preliminary trial results are showing that the Easy P strategy is an effective supplementation method. Hopefully, these results will inspire the adoption of phosphorus supplementation in areas where wet season access currently prevents it from occurring.

Bullo River Station has set up a Producer Demonstration Site to demonstrate the Easy P strategy on a commercial property. An on-site field day will be held in September 2023.

Watch this space for more information!

Read more…

Details about the Easy P project →

The importance of phosphorus →

How much phosphorus cattle need →

Diagnosing phosphorus deficiency →