Tail hair test tells nitrogen efficiency in cattle: UQ research

Five years of research on the part of animal production scientists at The University of Queensland has now culminated in a proven, simple test that uses tail hair samples to identify an animal's ability to recycle nitrogen and thus produce extra protein.

It is expected an estimated breeding value for nitrogen efficiency will be developed from the groundbreaking science.

Associate professor Luis Prada e Silva, from UQ's Queensland Alliance for Agriculture and Food Innovation, said it was clear over the course of the project that beef producers had a huge appetite for breeding value information and see big value in nitrogen efficiency.

"Selecting animals that are more efficient in using nitrogen would be very useful to increase performance in low-protein diets, such as during the dry months in the north," he said.

The research has demonstrated the trait has around 40 per cent heritability.

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Dr Prada e Silva said he first started looking into the role nitrogen was playing when he arrived in Australia from Brazil, another big beef producing nation, and was astounded at how well northern animals were able to perform in what were often very harsh conditions.

Previous research had shown isotopes can be used to identify what animals are eating and Australian data from as far back as the 1970s had demonstrated bos indicus cattle were more efficient on a low-quality diet.

"How diet leaves a permanent signature on an animal is fascinating, and we were wanting to know how different animals handle nitrogen so we decided to find a way to test for the ability to preserve nitrogen," Dr Prada e Silva said.

The work has proven the efficiency of animals is related to their ability to maintain high nitrogen in the body and not lose that in the urine.

The trait can also be used to identify animals that would respond well to a urea supplement, potentially allowing producers to separate animals that will give a good response from those that won't.

The study was a collaborative effort between UQ, the Queensland Department of Agriculture and Fisheries and Meat & Livestock Australia.

In a complementary study, also funded by MLA, the tail hair test was able to identify cows with better reproductive performance.

"This is important because better nitrogen efficiency in cows was associated with better body condition score and better fertility," Dr Prada e Silva said.

The hope is in the very near future beef producers will be able to simple take a tail hair sample, post it off to a laboratory and have the valuable decision-making information at their fingertips within a very short time.

No special storage or transport requirements were needed for the sample, scientists said.

"The procedure to test isotopes on tail hair is well developed," Dr Prada e Silva said.

His colleague, QAAFI research scientist Dr Karen Eyre, said the hair shaft held a wealth of information.

"This is different to collecting DNA because we don't need the bulb at the top of the tail hair but can measure the isotope at any part of the hair shaft," Dr Eyre said.

"If we had a really dry period, we could measure back down the hair shaft and find those animals that are more efficient at using nitrogen during that time and either maintained their weight or at least didn't lose as much weight as the rest of the herd."