The animal's internal furnace, powered by hay
Across drought-stricken grazing country, the pressure to cut costs has led some livestock producers to reduce roughage in favour of more concentrated feeds — a choice that carries hidden dangers far costlier than the hay it replaces. The ruminant digestive system is built around long fibre, and in winter that fibre becomes both a biological necessity and a source of warmth, as fermentation in the rumen generates the internal heat animals need to survive freezing nights. Agriculture Victoria's veterinary staff are reminding producers that roughage is not a line item to trim but a foundation of animal health — one whose absence invites acidosis, rapid weight loss, and metabolic disease.
- Drought is forcing producers into painful feed cost trade-offs, and roughage is being quietly sacrificed in favour of grain and pellets that seem to offer more nutrition per dollar.
- Without sufficient long fibre, ruminants cannot properly ruminate, and the rumen turns dangerously acidic — leading to acidosis or grain poisoning that can kill stock and generate veterinary bills dwarfing the cost of the hay skipped.
- Winter cold compounds the crisis: animals stripped of roughage must burn their own body fat to stay warm, and condition can collapse with alarming speed through the coldest months.
- Roughage also serves as the practical delivery mechanism for mineral supplements like Causmag, and its absence disrupts protection against metabolic disorders such as grass tetany.
- Producers are being urged to feed roughage in the late afternoon so that the heat generated by rumen fermentation peaks during the coldest night hours, helping animals hold condition rather than haemorrhage it.
Drought has squeezed feed budgets across the region, and in that pressure roughage — hay, straw, fibrous feed — can look like an easy cost to cut. Grain and pellets promise concentrated nutrition, and the temptation to lean on them is understandable. But reducing roughage in winter is a false economy with serious consequences.
Ruminants like cattle and sheep depend on long fibre to keep their digestive systems functioning. Fibre triggers cud chewing and rumination — what veterinarians call the 'scratch factor' — which maintains a healthy rumen environment. Without it, animals fed predominantly on grain or pellets develop dangerously acidic rumens, leading to acidosis or grain poisoning. The veterinary costs of treating affected stock far exceed the price of the hay that would have prevented the problem.
Winter intensifies the stakes. When temperatures fall, livestock burn more energy simply to maintain body warmth. Roughage provides that energy in a uniquely direct way: the fermentation of cellulose in hay or straw generates heat inside the rumen itself, functioning as an internal furnace. Animals denied adequate roughage in freezing conditions are forced to deplete their own body fat reserves, and weight loss can be rapid and severe.
Roughage also plays a practical role in mineral supplementation, acting as a reliable vehicle for delivering Causmag and other treatments that guard against metabolic disorders like grass tetany. And the timing of feeding carries real weight: offering roughage in the late afternoon means the peak of digestive heat coincides with the coldest hours of the night, helping animals hold condition through to morning.
Agriculture Victoria's veterinary staff are clear on the matter — roughage is essential infrastructure, not filler. Producers navigating difficult feed decisions are encouraged to consult their local vet or the Agriculture Victoria animal health team before cutting it from the program.
Drought has tightened the margins for livestock producers across the region, pushing feed costs higher and forcing difficult choices about what to put in front of their animals. In that squeeze, roughage—hay, straw, and other fibrous feed—can seem like an expense to minimize, especially when grain and pellets promise more concentrated nutrition. But skipping or cutting back on roughage in winter is a false economy that can damage animal health and burn through body reserves faster than any drought.
The digestive system of cattle, sheep, and other ruminants depends on a steady supply of long fiber. Even if some of it passes through uneaten, that roughage serves a critical function: it triggers the animal to chew its cud, a process called rumination that keeps the rumen working as it should. Veterinarians call this the "scratch factor." Without it, when animals are fed only grain or pellets, the rumen can become too acidic. The result is acidosis or grain poisoning—serious conditions that can sicken or kill stock and rack up veterinary bills far larger than the cost of the hay that would have prevented them.
Winter adds another layer of demand. As temperatures drop, livestock need more energy just to stay warm. This is where roughage becomes not just a digestive necessity but a survival tool. When an animal breaks down the cellulose in hay or straw, that fermentation process generates heat inside the rumen. It is, in effect, an internal furnace. Animals that do not get enough roughage in freezing conditions are forced to burn their own body fat to generate warmth, and weight can drop with alarming speed.
There is also the matter of grass tetany, a metabolic disorder that can strike in winter and spring, and the practical need to deliver mineral supplements like Causmag to the herd. Hay provides a reliable vehicle for both.
The timing of feeding matters too. Producers who feed roughage in the late afternoon can harness that digestive heat when it is needed most—through the coldest hours of the night. It is a simple adjustment that can make the difference between animals holding condition and animals losing weight they cannot afford to lose.
For producers working through the drought and weighing every feed decision, the message from Agriculture Victoria's veterinary staff is clear: roughage is not a luxury or a filler. It is essential infrastructure for keeping livestock healthy, preventing costly disease, and getting them through winter intact. Those with questions about their feeding program should reach out to their local veterinarian or Agriculture Victoria's animal health team.
Citas Notables
Livestock require a minimum amount of fibre and long roughage to maintain healthy digestive function, even if some of it is left uneaten.— Dr Jeff Cave, Senior Veterinary Officer, Agriculture Victoria
The fermentation and breakdown of cellulose in the rumen generates internal heat, effectively helping to keep the livestock warm from the inside out.— Dr Jeff Cave, Senior Veterinary Officer, Agriculture Victoria
La Conversación del Hearth Otra perspectiva de la historia
Why does roughage matter so much if grain and pellets have more calories per pound?
Because a ruminant's stomach is not designed to work on concentrate alone. The animal needs to chew, to ruminate, to keep that fermentation process moving. Without it, the whole system goes acidic and breaks down.
So it is not really about the calories—it is about the mechanics of digestion?
Exactly. The roughage is the thing that keeps the engine running. You can have all the fuel in the world, but if the engine is not working, you have a problem.
And in winter, roughage does something else entirely?
Yes. The fermentation of fiber generates heat. It is the animal's internal heating system. In a drought year when feed is expensive, that heat is free—but only if you provide the roughage to ferment.
What happens if you do not?
The animal burns its own fat reserves to stay warm. You watch the weight come off in days. By spring, if they survive, they are depleted and weak.
Is there a way to make this work economically in a tight year?
Feed late in the day so the heat generation happens when the cold is worst. It is not about feeding more—it is about feeding smarter. And it prevents the disease bills that come from skipping roughage altogether.