Maximising the returns from pasture
Southern Australia's environment is broadly Mediterranean, which means it typically experiences a forage deficit during the hot summer and cold winter months. Additionally, pasture quality tends to be low during the senescence and dormant periods, which extend from late spring until the first significant rainfall in autumn. For these systems, annual pasture production can range from 5 to 15 tonnes of dry matter per hectare.
Pasture production and utilisation are the fundamental elements of the grazing enterprise. The primary objective for ruminant production systems is to leverage pasture as a cost-effective feed source to achieve the highest possible return on the farm's asset or capital value. Agricultural land is one of the largest assets in a farming business. Its value is tied to what it can produce, whether that be pasture, forage, grain crops, or other outputs.
Furthermore, the potential for pasture production, which varies both within and between years, is largely governed by environmental factors such as climate, rainfall amount and distribution, temperature, and soil type. Consequently, achieving high pasture and forage production is crucial to maximise returns from the fixed land resource.
Pasture utilisation – converting pasture to product
The ultimate goal is to convert this pasture into marketable products like meat and wool to generate income. However, typical pasture utilisation rates peak at 55-60% and can be as low as 10-20%. Often, less than half of the pasture grown is actually consumed by the animals to produce meat and wool. Pasture utilisation is a well-established indicator of the profitability of sheep enterprises. It's a direct consequence of the stocking rate per unit of area, which in turn directly influences the amount of meat and wool produced, and therefore the level of income.
Achieving maximum pasture utilisation and profitability often involves a delicate balance between stocking rate, time of lambing, and lamb turnoff weight. Traditionally, wool-focused systems have favoured spring lambing to avoid harsh winter weather and to align stocking rates more effectively with feed availability. However, these systems often face issues with unfinished lambs and lower weaner survival due to smaller lamb size and weight entering the summer feed deficit.
Conversely, lamb production enterprises have historically opted for autumn lambing to allow lambs more time to grow and reach heavier weights before pasture supply and quality decline in late spring and early summer. However, earlier lambing exposes ewes and lambs to inadequate nutrition during periods of high energy demand, forcing these systems to operate at lower stocking rates to avoid excessive feed supplementation due to the mismatch between feed supply and animal demand.
Moreover, ewes mated in late spring and early summer can experience lower conception rates and smaller litter sizes due to seasonality of reproduction. Consequently, autumn lambing systems tend to have lower pasture utilisation and profitability due to lower stocking rates and fewer lambs.
Economically efficient farms are more likely to lamb between late winter and early spring and maintain higher stocking rates to maximise pasture utilisation, product output, and profitability. Nevertheless, high stocking rates and later lambing can reduce the performance of individual ewes and lambs, as well as the time available for lambs to reach maximum slaughter weights. Therefore, successful enterprises often trade-off some individual animal performance to achieve high levels of per-hectare and whole-farm profit.
The impact of stocking rate on animal performance
Stocking rate is a central factor influencing both pasture utilisation and animal performance. There exists a trade-off between maximising stocking rate for higher per-hectare productivity and maintaining optimal individual animal performance. Ultimately, the negative impacts of increased stocking rate on lamb and wool production are largely indirect, stemming from reduced feed availability and a decline in ewe live weight and condition score. These factors then cascade to affect reproduction, lamb growth, and wool production.
However, it's important to recognise that animal systems will invariably face pasture supply deficits, as the stocking rates needed to maximise utilisation and profitability, often exceed the carrying capacity of pastures during summer and autumn. Therefore, economically efficient management involves strategically allocating pasture resources through grazing management and supplementing animal diets to address shortfalls in pasture production.
Grazing management is key
Grazing management, which involves moving livestock in response to pasture growth, availability, and quality, is a crucial farm management activity. It can also be used to prioritise pasture resources for animals based on their needs and the prevailing pasture and seasonal conditions.
Grazing management generally falls into two categories: set-stocking and rotational grazing. Set-stocking involves keeping animals in a paddock at a constant stocking rate for extended periods. Rotational grazing, on the other hand, involves dividing larger paddocks into smaller ones and moving animals in larger groups through these paddocks, providing rest periods for pasture species while others are being grazed. The timing of movement in a rotational grazing system can be based on either time or pasture conditions, such as pasture amount or quality.
The chosen grazing management system can significantly influence the stocking rate and the production of both the animals and the pasture species. While many studies suggest that rotational grazing can increase per hectare production, it may come at the expense of per head lamb growth and ewe live weight. This can be attributed to reduced diet selectivity and a decrease in the actual clover or legume content of the pasture due to rotational grazing favouring the proliferation of grass species.
Set-stocking systems, with their continuous grazing, often experience pasture decline, and the persistence of productive species is a major limitation in these systems. When plants are continuously defoliated, their ability to store and translocate essential carbohydrates from their roots and stem bases is compromised, hindering regrowth after grazing. The decline of perennial species also encourages the proliferation of annual species.
Grazing management and supplementation
Given the inherent fluctuations in pasture supply and quality, effective grazing management and strategic supplementation become crucial farm management activities. The goal is to optimise individual animal production while maximising per-hectare profitability by carefully allocating pasture resources and addressing nutritional shortfalls.
As discussed earlier, the choice between set-stocking and rotational grazing can have significant implications for both animal and pasture production. While rotational grazing may offer the potential for higher stocking rates and per hectare production in some scenarios, it can also impact pasture composition and individual animal performance in others.
Set-stocking, while potentially simpler to manage, poses a greater risk to pasture persistence and can limit overall productivity if stocking rates are not carefully controlled. A stocking rate that maximises short-term profitability might lead to increased landscape degradation and reduced long-term sustainability.
The answer is a mixed system, a combination of both systems and the addition of some other critical elements are necessary in managing and utilising pastures to their maximum. Economically efficient farms usually employ a combination of rotational grazing when pastures are slow in growth rate (autumn/winter) and set stock when animal systems require no movement (e.g. lambing). They also re-enter rotational grazing with large mobs when pasture mass is excessive and when feed quality needs to be managed with higher grazing intensity.
A powerful addition to these grazing systems is the use of containment feeding. Animals are contained in small areas and supplementary fed, often during the late summer and autumn period. These systems have the benefit of using lower quality straws and hays with grains, while limiting the energy loss of ewes from grazing and walking in larger paddocks.
Containment allows pasture at the autumn break to build leaf area, compounding its growth rate through the autumn period leading to higher feed on offer through the winter period. This is not a new concept, and “deferred grazing” systems have been extensively researched during the eighties, but it has only been in the last 10-15 years where they have been used as a regular tool in the grazing management of sheep systems.
These economical efficient farms also employ simple solutions to make these grazing systems more effective. For example, they will have a shorter joining and lambing period so animals can be moved sooner after lambing, ensuring animals don’t overgraze or lose significant weight. They will wean on time or earlier in response to the conditions, enabling ewes to groups together into larger mobs for greater grazing intensity, while prioritising lambs to higher quality pastures.
In summary, what does an economically efficient farm that maximises pasture utilisation look like in southwestern Victoria? It is likely to have the following attributes:
Lambing window: Usually set for late winter to early spring, so that peak feed demand from lactating ewes and growing lambs coincides with the high-quality feed in the spring.
Shortened joining: shorter lambing window, resulting in more uniform management and reduces the amount of time of set-stocking at lambing.
Higher stocking rate: Efficient farms tend to push the stocking rate to capture more of the pasture’s potential yield.
Trade off: Recognises that pushing stocking rates can lower individual growth and ewe condition score but more than compensates by boosting total meat and wool output per hectare. Doesn’t hesitate to supplement to fill shortfall and maximise production.
Feed budgeting: Regularly measures and tracks pasture quantity and quality to ensure decisions are timely (e.g., introducing supplementation, destocking/restocking trade animals, etc.).
Rotational grazing: Subdivides paddocks to concentrate grazing pressure, allowing rest and regrowth, particular during critical growth periods or deficits.
Timely set-stocking: May revert to short-term set-stocking during lambing or at other key times to simplify management or protect vulnerable classes of livestock.
Containment Feeding: Often employs containment areas over late summer/autumn to spare paddocks from overgrazing, maintain groundcover, feed ewes efficiently and build a feed wedge for winter/spring.
