Research Questions/Objectives:
Brief Description of the Project: Faecal seeding is a common methodology in practice which can be utilized to introduce legumes into grazed pastures. However, there is very little data regarding species in northern Australia, and whether hard or soft Desmanthus seeds are more likely to survive the gastrointestinal tract, and how many of those seeds remain viable for germination in the paddock afterward.
Background and Significance of the Research Question to drought risk, vulnerability, preparedness, or resilience: The pasture legume Desmanthus is a drought hardy species which can improve biodiversity of the northern Australia rangelands and productivity of the livestock raised there. In drought prone semi arid regions graziers are seeking inexpensive ways to enhance drought resilience and productivity, and faecal seeding is a potential tool to assist them.
Desmanthus seed is very hard seeded and will pass through cattle digestive system and remain viable. It is already known that Desmanthus seeds will survive in dung after faecal seeding up to 9yrs later, and a follow up study is required to determine whether which species is best suited to survive digestion. In a pen study we will feed seeds to cattle and test hard versus scarified seed for passage time and viability.
Thus, informing graziers and seed merchants if they should feed hard or scarified seed in their supplements for best germination and ultimately legume establishment. We will also be able to definitively establish how many of the seeds fed to cattle survive, allowing producers to be more accurate and efficient when using faecal seeding to establish legumes in their paddocks.
Academic and research experience relevant to the honours project:
James Cook Uni Veterinary Science 3rd year (TV3002) literature review and research project re: faecal seeding and seed recovery from dung in 2022.
– Abstract published and findings presented at NABRUC 2023 in Darwin on the viability of Desmanthus after 9yr drought simulation.
– Current veterinary undergraduate student (due for graduation Dec 2024) and pursuing extra-curricular research opportunities alongside Chris Gardiner.
Principal Supervisor’s skills and experience in relation to this project topic:
I’m a 5th year Veterinary Science student at James Cook University, and the aim of my research is to improve knowledge and confidence around the use of faecal seeding to assist legume uptake in northern Australia. There are so many innovative producers who are looking to increase the protein content of their pastures, and all they need is the tools to make the best choice. I love when agriculture and science work together to find the most effective solutions to an industry problem. I’ve always loved the medical and scientific fields and worked in healthcare for years. However, growing up in agriculture meant I was always secretly wishing I was back in the paddock and cattle yards, so returning to study vet science in Townsville allows me to live out both passions.
Future Career Goals:
After graduation this year I am aiming to work in a mixed practice in northern Australia, where there are significant vet labour shortages and I could be of use. This would also allow me to be remain connected to the producers and their issues, and potentially continue research where it is needed most.
Background
There is considerable interest in faecal seeding as a method of establishing legume pastures in northern Australia. Faecal seeding occurs when livestock consume seeds which survive the digestive tract and are deposited in dung and over time, germinate and become established. Producers in rangeland grazed environments in northern Australia who wish to establish legumes into their pastures may not have farming equipment or land types suitable to undertake conventional mechanized planting of pasture seed. However, they do have livestock which graze across their paddocks and are fed dry season supplements. The inclusion of legume pasture seeds into these supplements creates a low-cost and minimal input option for dispersal across paddocks via the cattle that consume it. There are many benefits with the addition of legumes to pastures including nitrogen fixation, which improves soil health and the native or sown pastures that grow nearby, drought resilience through their deep tap roots and prolific seed bank reserves in the soil, improved diet quality and increased efficiency of production, reduced methane emissions, and ecosystem biodiversity benefits. Considerable amounts of seed of another common legume, Stylosanthes, has been established via faecal seeding across northern Australian light textured soil land types. However, clay-based regions are unsuited to this seed and producers have shown considerable interest in using the more suitable Desmanthus legume for faecal seeding into clay soil environments. Desmanthus has a growing body of research around its durability and viability in clay-type soils and drought hardiness, but there is minimal data to date on the most effective way to disperse these via the use of livestock.
The aim of the project is to provide data to assist producers with decision-making around faecal-seeding Desmanthus legume seeds in northern Australia. The data points are whether hard or soft legume seeds have better germination rates, exactly how long it takes for the seeds to transit through the gastrointestinal tract, what percentage of seeds remain viable after being digested and excreted, and the number of seeds in each dung pat over the course of several days. This linked with previous research assessing the germination rates of faecal-seeded Desmanthus after a prolonged period of drought.
Methods
A small clinical trial was designed to meet the above goals with statistician input, and animal ethics approval given in February 2024 (JCU Ethics Application A2954). Three steers were already on site at JCU Veterinary Science campus for another long-term research project with Future Feeds, and consent was given by the owner for their use in the trial. The 3 steers had a comprehensive health assessment by Dr. Paul Nilon (veterinarian and James Cook University staff lecturer) and were moved from a grass grazing paddock into a cleared dirt pen with shade and water for a 2-week transition diet of lucerne and mineral supplement mix.
The steers were then moved on to a 4m x 4m undercover concrete pen with ad lib lucerne hay, mineral supplement mix and fresh water for 4 days. They were randomised into their pens and then randomly assigned either hard or soft seed Desmanthus. Each steer was given 250g (250,000 seeds) of their assigned Desmanthus seeds mixed with 200ml of molasses and observed until they had consumed it all. Every dung pat from each steer was then collected for the next 72 hours, given an individual identification code, and placed in an industrial oven at 50’C for 1 week, or until completely dry. After 72 hours the steers were returned to their dirt pen for 7 days of transition diet for the washout period, then returned to the concrete pens for round 2. They were randomly assigned different pens and either hard or soft Desmanthus seeds, and each individual dung pat was again collected, identified, and dried in the ovens. The animals were weighed and assessed before the transition period, before each round, and after the trial ended.
All the dung pats from the 24-48hr period were sieved and weighed, then the seeds extracted using a combination of sieving and rinsing, before the seeds were returned to the oven to dry again. The seeds from each dung pat were then weighed and counted. There was also a subset of dung pats from each steer over the full 72-hour period that were also sieved and weighed.
The seeds from each dung pat were then combined into their respective hard and soft categories, and then split in half. One half of each was left untreated, and the other half was scarified with hot water for 1 minute. A subset of seeds from each group were germinated in a lab as either digested soft seed (scarified and unscarified) or digested hard seed (scarified and unscarified), along with a control sample of scarified and unscarified seeds. This germination trial is currently underway in a laboratory at JCU Veterinary Science precinct and will continue for 28 days (due for completion on 3rd December 2024).
Results
While no formal data or statistics have been completed yet, there are already definitive results. The steers created an average of 10 dung pats per day, and gained an average of 50kg over the course of the 29-day trial period with no ill effects. The hard seeds appear to have passed through the digestive tract in greater numbers compared to the soft seed group. The unscarified control seeds have had very little germination to date, with the scarified control group over 50%. The soft seeds (both scarified and unscarified) have seen very little germination to date, with high numbers of unviable seeds being removed from the petri dishes for both of these groups. The germination rates of the hard seeds, both scarified and unscarified, are over 70% already on day 4 currently.
Once the germination trial is completed, the results will be statistically analysed and completed by early 2025. The aim is to finalise the data and write up, then abstracts will be sent to appropriate journals and conferences by April 2025.
Update to be provided.
