Shifting thinking on P brings all-time pregnancy highs

Allison Hotz suspected phosphorous (P) deficiency was behind fertility issues in one of her Droughtmaster herds, even though others in the Banana area told her that couldn’t be the problem.

It’s one of the reasons she decided to get involved in MLA’s P Challenge in 2019, an awareness exercise to determine the P status of cattle herds through testing for plasma inorganic phosphorus (PiP), which revealed P deficiency in some of her cows.

Through identifying the problem and beginning to supplement for P, Allison has discovered production benefits along the way.

Identifying the problem

Allison said she first started to consider P deficiency in her cattle when she noticed reduced fertility rates in one of her mobs of cows.

“The average pregnancy rate for my cows was approximately 90.5%, but one particular mob on our block ‘Wylie’ came back at 78% and 80% two years in a row, even though the cattle there were under the exact same conditions as the others on our blocks ‘Inala’ and ‘Mulawa’,” she said.

“I was suspicious that it was P because whenever we brought that mob into the yards, they would always try and chew on bones.

“My vet suggested we should do some testing, even though people in the area said P had never been a problem here. 

“After the tests came back, they showed acute deficiency in P.”

Allison also tested the soil in the paddocks on the once farmed country on Wylie where her deficient mob was run, finding significantly lower P levels than on her other blocks.

Supplementation begins

When the P deficiency was identified Allison decided the time was right not only to begin a supplementation program, but also to brush up on her knowledge of ruminant nutrition.

“I attended a Nutrition EDGE course that was immensely helpful,” she said.

“Previously, we only had minor supplementation during the dry once the grass had lignified.

“Now, not only do I supplement P, but we developed and used new mixes during the drought for our breeders and are presently feeding sale bulls rations utilising what I learnt from the Nutrition EDGE course and consultation with our vet.”

Allison said they bought covered troughs and now feed P in every paddock even though only one property was identified as being deficient, as the cattle cycle all properties.

“When we first put P out, the cattle just went for it like you wouldn’t believe,” she said.

“Even though their consumption has remained highest on the block where we identified the deficiency, the other mobs consume it as well it so it’s worth having it there too.

“The big thing with our P supplementation is that it’s ad lib – it’s available year-round and the stock can have it when they want it.

“When we started, we were putting out a commercial mix, then Kynofos21 mix with 50% salt, however, we’ve now reduced the salt substantially.

Allison tested her cattle for P again in 2020 after beginning supplementation and saw noticeable improvement in their levels. She says ongoing monitoring and testing will help to make decisions about the supplementation strategy going forward.

New management approaches paying off

Allison believes that P supplementation is just one of the reasons they’ve been able to boost production within their herd over the past two years, and that other management approaches have been critical.

“More broadly, I’m joining my animals earlier, all heifers are inseminated, then have two cycles with the bull,” she said.

“Long-term, this protocol along with other management initiatives including P testing and supplementation has resulted in more cows getting back in calf, especially those first calvers.

“I’ve also started fecal nitrogen testing as a result of the Nutrition EDGE course, which has been very helpful to inform me if the plane of nutrition is sufficient during the dry.”

Allison said even after two years of changes, the results have been noticeable.

“We’ve had a wonderful season this year which helps, but I think the P supplementation and other management tweaks have been the key to lifting our weaning and pregnancy rates to the highest they’ve ever been. 

“We’ve also noted reduced mortality overall, our cull cows’ dressed weight has improved and our cattle are visually looking much healthier than they were 24 months ago.” 

As for P, it’s something that Allison recommends every producer should investigate.

“I think some people see P as another expense and something else they have to deal with, but we consider it an investment because it’s improved our overall productivity and accordingly, profitability,” she said.