Frequently asked questions about FNIRS

As the season progresses and the pasture starts to hay off, the quality of the pasture, in terms of energy and protein, declines, often falling below the nutritional requirements of the cattle. In such circumstances, cattle will either stop growing, lose weight, and sometimes in the case of breeders, cease cycling. Providing a dietary supplement that addresses the deficiency during these periods will help to reduce the rate of weight loss or promote weight gain and encourage cows to cycle regularly.

Analysing dung samples using FNIRS will tell you when the nutrients provided by the pasture are not meeting your herd’s nutritional requirements, indicating when the animals will respond to supplementation.

The team at Brian Pastures Research Facility (near Gayndah) use FNIRS testing to ensure cattle have optimal nutrition to meet production goals of gaining weight, conceiving, and raising a calf.

“We use FNIRS multiple times a year to make timely decisions, including when to start, and when to change, the type of supplement used,” said Melissah Dayman, DAF Technical Officer at Brian Pastures Research Facility. “At the end of the growing season (usually in May), dung samples are taken to determine whether urea is required to counteract the decline in crude protein in pastures. As the season progresses, samples are taken monthly to determine if the current supplement is meeting the animals’ requirements, and to decide whether to switch over to an energy-based supplement, such as M8U (molasses with 8% urea),” Melissah said.

“Changing supplement shouldn’t be based off visual assessments. By the time you notice a decline in cattle body condition, and/or a decline in pasture quality, the nutritional gap is already having an impact,” Melissah continued. “This happened to us in 2019, when supplementation of the breeder herd did not begin until June. Although faecal samples were collected monthly, they were only sent for analysis every three months. So, when we got the results back, we could see that the dietary crude protein had been below maintenance levels since January. As a result, the cows lost weight. Obviously, we’ve learnt from that experience, and we now sample, and send our tests off for analysis, regularly.”

Read more of Melissah’s FNIRS and supplementation story →

Whilst one FNIRS analysis provides a good indication of the current dietary status of the mob tested, it is only a snapshot of the diet in that paddock, at that point in time. For this reason, DAF Principal Beef Extension Officer, Mick Sullivan, recommends collecting faecal samples at key times of the year.

“One of the key reasons to undertake dung sampling is to know when it will be beneficial to begin supplementing the herd with protein,” Mick explained. “We all know, as the season progresses and the pasture hays off, the protein content, and to some degree the energy content, in the pasture declines. Therefore, dung sampling for diet quality testing as the pasture quality declines, so say regular sampling in the months between April and July, will tell you when the cattle will have a positive response to urea or other protein supplements.

“The risk comes mostly with females of breeding age,” continued Mick. “If the pasture isn’t meeting their requirements for maintenance, they will begin to lose weight and possibly stop cycling, thereby impacting their lifetime reproductive performance.

“You can also use the information to conduct a cost benefit analysis of feeding dry stock destined for sale — will it pay to supplement these animals if they’re going to be sold before the next wet season? If so, providing a protein and/or energy supplement to maintain or improve weight gain may be beneficial. If not, there is the potential for the dry stock to experience compensatory growth over the wet season, making additional supplementation not cost effective,” Mick added.

FNIRS testing can also help identify which paddocks and land types provide better livestock nutrition. Mick explained, “Soil types differ in the nutrients they provide to the plants, and therefore to the stock. Understanding which land types and paddocks provide better nutrition can help producers match stock class to paddocks.”

To help the scientists analysing the samples understand the nutritional requirements of the herd you’ve collected samples from, they also need to know information such as:

• land types and major pasture species
• paddock history such as burning or flooding
• class and pregnancy status of the herd
• pasture condition
• any supplements that the cattle have access to.

Both companies offering FNIRS analysis provide data collection templates.

FNIRS tells you different things to soil and water tests.

When asked this question, DAF Senior Beef Extension Officer, Roger Sneath, said “Soil tests inform mineral status relevant for plant growth but can also indicate if phosphorus could be deficient for stock. Water informs pH, minerals (e.g., salt levels) and contaminants. FNIRS helps you learn about the levels of digestibility (energy) and protein that the stock are selecting from the paddock at the time of sampling, and if and when a protein supplement might or might not be beneficial.”

“Besides the overall levels of energy and protein,” Roger continued, “checking the ratio of protein to energy indicates if there is enough protein relative to the energy. For example, if the protein figure divides more than eight times into the digestibility figure it is likely that protein is too low relative to the available energy and there would be a response to a urea or protein supplement.”

Roger provided the following example from the South Burnett region:

• Digestibility 56%
• Crude protein 4%

= 56÷ 4

= 14, meaning that in this scenario, the digestibility to crude protein ratio is 14:1.

In the above example, supplying nitrogen (e.g., urea lick with enough sulphur) or protein will help rebalance the diet, resulting in increased rumen microbe activity, allowing them to digest potentially up to 30% more dry grass per day. The extra bacteria that grow are about 50% crude protein and are also a protein source for the livestock.

“FNIRS also indicates how much ‘non-grass’ plants the livestock are selecting in their diet such as herbage and browse. Additionally, if you are doing FNIRS testing you can also ask for a phosphorus test to have a rough gauge of how much phosphorus livestock are getting in their diet.” Roger added.

“When collecting dung samples for the purpose of getting an idea of the level of herd nutrition, we’d recommend collecting a teaspoon sized amount from between 10 to 20 fresh samples,” said Mick Sullivan, DAF Principal Beef Extension Officer.

“The best place to collect samples is to go to a watering point during the middle of the day, as you will find fresh dung to collect samples from,” Mick continued.

General rules of thumb for collecting samples include:

• Making sure your sampling container or zip lock bag is already labelled with paddock name and mob details as well as date.
• Using a clean teaspoon, remove the top layer of the dung, taking a teaspoon sized sample from the middle, making sure not to collect soil in the process.
• Avoid collecting samples from manure with dung beetle activity in them, as the dung beetle tunnels will contaminate the sample.
• After collecting between 10 to 20 fresh dung samples from the herd, mix it together to ensure what is being sent to the lab is a true representation of the herd and not just from one individual.

To the relief of everyone in your household, no, you don’t!

Faecal samples can be sun-dried easily at home. It takes approximately a day to dry the sample and then once the sample is put into a plastic bag and sealed off, it can be posted as per normal mail.

1. Place the bulk sample on an aluminium cooking tray or some aluminium foil or some other non-absorbent sheet such as galvanized iron.
2. Spread the sample out to a thickness of 1 cm, ensuring that the sample stays in one piece. This makes it much easier to turn the sample over to dry the other side.
3. Ensure that you label each sample to prevent any mix-ups.
4. Place the sample up high, in a sunny position, such as a rainwater tank, where it is free from wind, dogs and dung beetles. A cover of mesh or gauze can also be placed over the sample to prevent the wind from blowing it over.
5. The sample can be turned over after approximately twelve hours to dry the bottom side.
6. Once the sample is dry, it is important that it is allowed to cool thoroughly before it is ready for posting.

Ben McKenzie of Yaralla, near Cunnamulla, attended a nutrition workshop in 2017. As a result, he conducted FNIRS testing on his herd where he learnt that the commercial supplement he had been using wasn’t addressing his herd’s nutritional deficiencies. With the aid of a ruminant nutritionist and reputable supplement company, Ben created a customised lick for his cattle, minimising further weight loss from his breeders.

Read more about how Ben made these changes →

The percentage ash as reported in a FNIRS test indicates dung mineral content and potentially soil sample contamination. “There’s a few things a high ash percentage on an FNIRS test result could indicate,” said Melissah Dayman, DAF Technical Officer. “It could simply be that dirt got into the sample you collected – perhaps you accidentally collected some soil when you took the sample, or perhaps scooped up a dung beetle tunnel in the process,” Melissah continued. “Another possible cause of that result is that your pasture is too short, and cattle are picking up dirt when they graze. Alternatively, it could be that your cattle are accessing far more minerals than they need to maintain themselves.”