Seasonal Update Autumn Winter 2024
Patrick Francis
The best way to describe the 2024 autumn/winter climate was ‘highly variable’. Rainfall ranged from 0mm in March to 71mm in July. June rainfall was less than half the average while July reached the average. Such variation adds considerable uncertainty for managing livestock numbers so stocking rate matches year round carrying capacity and making decision about pasture renovations.
With BOM climate outlooks indicating chance of average rainfall through the period was below average we opted to reduce carrying capacity by culling breeding ewes more heavily and selling all weaners before the end of June. The objective was to remove the need for supplementary feeding over winter and ensuring lambing paddocks had in excess of 3000 kg green dry matter per hectare by early August and were infective larvae free. Lambing paddocks were removed from the grazing rotation from mid-May to mid-June.
Of particular interest in these lambing paddocks is to watch the response in perennial clovers growth during extreme cold months. Temperatures in June and July are generally in the 1 to 10C range but this year there have been more below 0C mornings than usual. The pasture species most affected by such cold temperature is chicory, we don’t expect to see any growth from it until early September. Perennial clovers and ryegrass continued to grow through the cold days.
Pasture renovation
Our pasture renovation program in spring 2023 was negatively impacted by extremely wet soil which resulted in the direct drilling giving patchy germination and in one paddock allowed the bent grass to survive despite the knockdown herbicide applied. In another paddock the patchy clovers, chicory, ryegrass germination was not accompanied by bent grass and sweet vernal grass survival which opened the door for re-sowing in autumn.
After grazing the paddock in March I direct drilled more clovers, chicory and perennial ryegrass into dry soil in early April. No knockdown herbicide was needed and when rain eventually arrived three weeks after sown germination looked good. How good it is will not be seen until about mid-September.
Figure 1: Failed spring 2023 pasture renovation paddock being re-direct drilled with chicory, perennial clovers and perennial grasses after a dry February and March 2024 without using knockdown herbicide. Photo: 25 March 2024
The paddock where bent grass continued to grow after last spring’s sowing will have knockdown herbicide applied to the infected areas in spring 2024. The parts of the paddock with strong chicory, clovers and ryegrass will not be sprayed but will be direct drilled with the rest of paddock when soil moisture and temperature conditions are suitable in mid-Spring.
Figure 2A: Prolific clover and chicory growth in December 2023 and lambs grew at an average 330grams per day.
Figure 2: Same paddock in late April 2024 after rain which followed zero rain in March. Chicory growth has responded but not the perennial clovers. Lambs grew at an average 100grams per day suggesting a chicory palatability and/or species balance impacting intake and digestibility.
In one spring 2023 pasture sown paddock, the patchy chicory clover germination was producing excellent looking feed but the lamb growth results suggest what looks good feed may not necessarily meet the livestock’s requirements. The first weaners to graze this new pasture in December January grew at an average 330grams per day, but the last batch grazing it in April grew at just 100grams per day. The difference between the two grazings was a wet early summer and prolific clover plus chicory growth figure 1A, but after a record dry March the clover had disappeared and the chicory regrew after early April rain, figure 1B. Without clovers the dominant chicory seems to have been a less balanced diet and could have also been less palatable.
Weaned lamb growth rates on our renovated pastures continued to provide questions around the impacts of species and palatability. The science behind weaner lamb and cattle pasture based nutrition has been researched for years and the take home messages are clear. Pastures species vary in their nutrient composition particularly in digestible protein, metabolisable energy, digestible dry matter, fibre composition, and trace element composition. Then there is the importance of amount of pasture on offer (food on offer) and animal grazing ability including bite size and frequency. Other influences to daily intake are animal health status such as infective internal parasite larvae burden and susceptibility, grazing management such as rotational versus set stocking, and soil health issues associated with pH and nutrient content particularly plant available nitrogen All these factors impact daily digestible dry matter intake and can be managed by the farmer to some extent.
But one critical factor affecting intake that science does not seem to have a handle on is variation in plant palatability to the lamb or steer. I am intrigued watching what parts of a pasture lambs eat. See how they run their noses through the sward often without taking a bite but all of a sudden stopping to bite. The clovers, grasses and herbs can all look the same especially in spring or times of the year that soil moisture doesn’t limit growth but obviously they are not the same to the lambs and steers.
I’m not talking about pasture situations where there is ‘no alternative grazing’, that’s when the stocking rate is so high for so long that ruminants digestive systems drive them to eat virtually everything in the paddock. I’m talking about grazing systems where the pasture mass is of sufficient capacity and of sufficient species heterogeneity that the animal has choice around what it bites or leaves. My thinking is if the shepherd can supply more of the favoured species then it is highly likely daily intake will increase due to higher digestibility. This has positive impacts on productivity per hectare (higher growth rates) and lower methane emissions per hectare (lower greenhouse gas emissions intensity per kg of live weight).
There are lots of obvious examples on Moffitts Farm of weaned lamb pasture species preferences.
Firstly the unliked:
* Yorkshire Fog grass
* Bent grass
* Silver grass
* Sweet vernal grass
* Demeter tall fescue
* Native grasses such as kangaroo and wallaby grass.
* Plantain if under moisture stress
Secondly the liked:
* Chicory but not in moisture stress or not post the first frost
* Perennial clovers and sub clovers
* Most cocksfoot, tall fescues, phalaris and ryegrasses
* Fodder brassicas but usually takes 5 to 10 days and not when under moisture stress.
Research into ruminant livestock species preferences is limited but European scientists have shown that when ruminants have access to pure grass swards alongside pure clover swards, the animals will select a diet of around 70% legume and 30% grass. USA pasture scientist Dr Fred Provenza, Utah State University has been conducting research into ruminant livestock pasture consumption for 30 years. He is convinced that there are numerous secondary compounds in pasture species and varieties which impact palatability. The most well known are tannins and saponins that can have animal health and plant palatability/intake benefits in moderate concentrations but may limit intake at higher concentrations.
There is another important factor to be considered in livestock preferences for some grass species and that is their seeding morphology and tillering ability. When grasses cannot be prevented from seeding due to grazing management employed then some species have a seed stem morphology which shuts down future grazing. In our environment that is typified by bent grass (Agrostis tenuis). Its multiple flower stems are so thick and unpalatable sheep will not try to graze them and when thick in the pasture, the stems collapse smothering the soil surface. In contrast summer active cocksfoot species have fewer flower stems and continue to produce tillers with green leaves which sheep will consume while leaving the stems erect.
We are now using pasture topping in all paddocks we cannot prevent the grasses seeding to ensure no bent grass, Yorkshire Fog and Sweet Vernal stems remain while at the same time encouraging tillering in the summer rain responsive cocksfoots and ryegrasses. The other advantage provided by topping is opening up the sward to encourage perennial clover growth and chicory growth associated with summer rain.
Figure: Moffitts Farm late spring and early summer paddock stock rates are not sufficient to prevent grasses setting seed, particularly the less unpalatable species so we are topping paddocks to remove the stems and provide more sunlight for perennial clovers and chicory. The summer active desirable grass species will also send up new tillers (depending on rainfall) to add to the quantity of digestible pasture available for late summer and autumn grazings. Photo Patrick Francis.
Biodiversity
The highlight for biodiversity on Moffitts Farm this autumn winter has been the visit by at least two koalas, with one staying for three days which is unusual. What makes these koala visits even more rewarding is the fact that the Manna gum (E. viminalis)trees they sit in and feed on are part of the biolinks planted by the family in the 1990s in what were previously pasture paddocks.
Figure: It is difficult to know but having two koalas visit Moffats Farm in February and June 2024 may suggest these locally endangered animals are holding their numbers in the Macedon Ranges. Photos Patrick Francis
Some recently released CSIRO modelling of koala population across Australia suggests their populations are holding their own in most states. But the model data map for Victoria is a little difficult to believe especially the suggestion of populations west of Melbourne where koala habitat is mostly non-existent The Moffitts Farm experience shows how planting agro- forestry and biolinks not only ensure CO2 abatement but has the co-benefit of restoring biodiversity.
Figure: CSIRO modelling suggests the koala population in Victoria might be increasing. Source: CSIRO June 2024
The lowlight for biodiversity was the death of another mature male wombat killed by a vehicle going too fast through a wildlife hot spot on Moffats lane. As I have tried to explain numerous times to Macedon Ranges Shire Council and the Department of Transport and Planning (Vicroads) bureaucrats until they understand why the wildlife are crossing council managed roads in particular hotspots they won’t understand why band-aid measures like roadside wildlife warning signs are useless in preventing road kills. Moffats lane is just 2km long but has four council erected wildlife crossing signs and there are four Land for Wildlife signs on farm gates facing the lane. The simple fact is some drivers don’t take any notice of the signs and travel at up to the legal 100km per hour maximum speed limit. Furthermore the drivers who travel with little regard to wildlife collisions have their vehicles protected with roo bars so if they hit a kangaroo or wombat damage to the vehicle is unlikely.
Figure: The common theme to these Moffats lane road kills is they all happen close to Sandy Creek bridge which has adjacent fenced off riparian zones on either side which the wildlife use for habitat. Photos Patrick Francis
Signage words like “too fast” or “slow down” are meaningless without quantification and legal backup. The bureaucrats don’t ask drivers to slow down in built up areas instead there a strict legal speed limits set appropriately for the risk to human life. The same approach is needed for driving through wildlife hot spots – a legal speed limit must be signposted.
Figure: Despite virtual ‘saturation’ warning signage along the 2km long Moffats lane, wildlife are regularly killed highlighting that signs are not an effective method for reducing road kills on low traffic service roads where frequent users become immune to the message or don’t care about wildlife. Photos: Patrick Francis
