Cattle are grazers, and the quality of what they graze determines their health, their productivity, and ultimately what the farm earns. Choosing the best pasture for cows is therefore one of the more consequential decisions a livestock operation makes, and it is worth doing on the basis of how each species actually behaves rather than on general impressions.
Good pasture also lowers costs in a way that is easy to overlook. Money spent maintaining healthy grazing is money not spent on veterinary treatment for animals in poor condition. Prevention through good forage is almost always cheaper than treatment.
What Makes a Pasture Good
Four factors determine pasture quality, and they interact.
Grazing management
Balance is everything here. Under-grazing allows mature, low-quality material to accumulate, which reduces the feed value of the next grazing cycle. Over-grazing damages the plants and depletes root reserves, cutting productivity for seasons afterwards. Both the intensity and the duration of grazing need managing, which is why rotational systems generally outperform continuous grazing.
Forage quality
Nutrient content is highest when plants are growing actively, well supplied with water, and leafy rather than stemmy. Once a grass runs to seed, fiber rises and digestibility falls. Timing your grazing and cutting to catch the plant at the right stage is worth more than almost any other management decision.
Species selection
Grasses differ in nutrient content, palatability, growth season, and grazing tolerance. Critically, a species that makes excellent hay is not necessarily a good grazing species, and vice versa. Match the species to the use.
Soil fertility
The soil is the source of everything the plant contains. Nitrogen, phosphorus, and potassium all need to be at appropriate levels, but soil pH matters just as much and is often ignored. Below about pH 6.0, phosphorus and several trace minerals become chemically unavailable to plants regardless of how much fertilizer you apply. Test the soil before you fertilize; correcting pH is often cheaper and more effective than adding nutrients that the plants cannot access anyway.
Grass Species for Grazing
| Species | Season | Strengths | Watch For |
|---|---|---|---|
| Tall fescue | Cool season | Deep roots (up to 2 to 3 feet), genuinely drought tolerant, withstands heavy grazing | Toxic endophyte in older varieties. See warning below |
| Perennial ryegrass | Cool season | High protein, highly palatable, fast regrowth | Bloat risk on lush growth; poor drought tolerance |
| Kentucky bluegrass | Cool season | Excellent cold tolerance, spreads by rhizomes, forms dense sod that repairs itself | Shallow rooted, goes dormant in summer drought. Not a drought grass |
| Orchard grass | Cool season | Nutritious, very palatable, shade tolerant | Quality falls quickly once it heads out |
| Timothy | Cool season | Good fiber, reliable, widely used for hay | Slow to recover from heavy grazing |
| Bermuda grass | Warm season | Productive through summer heat when cool-season grasses stall | Dormant in cold weather |
A correction worth making explicitly, because it is frequently stated the wrong way round: Kentucky bluegrass is not a drought-tolerant grass. It has a shallow root system, typically only 4 to 8 inches deep, and it responds to summer drought by going dormant and turning brown. The deep-rooted, drought-tolerant cool-season grass is tall fescue, whose roots reach 2 to 3 feet. Bluegrass earns its place through cold tolerance and its rhizomatous, self-repairing sod, not through drought resistance.
Tall Fescue: Read This Before You Plant It
Tall fescue is an outstanding pasture grass in almost every respect, but it carries a risk that deserves far more than a passing mention.
Most older tall fescue, notably the widely planted Kentucky-31, hosts a fungal endophyte that produces alkaloids toxic to cattle. The resulting condition, fescue toxicosis, is one of the more costly livestock problems in regions where the grass dominates. Its effects include:
- Reduced weight gain and poor feed conversion
- Lowered conception rates and prolonged gestation
- Agalactia, meaning reduced or absent milk production
- Heat intolerance, with cattle standing in water or shade rather than grazing
- Fescue foot, a restriction of blood flow to the extremities that in severe cases causes the loss of hoof tissue or tail
The endophyte is what gives the plant much of its hardiness, so the answer is not simply to avoid fescue. Modern novel endophyte varieties retain the plant’s vigour and persistence while carrying a strain that does not produce the toxic alkaloids. Endophyte-free varieties also exist, though they tend to be less persistent under stress. If you are establishing new fescue, choose a novel endophyte variety. If you already graze older fescue, diluting the stand with legumes and managing grazing pressure reduces the impact.
Do Not Turn Hungry Cattle Onto Lush Pasture
This deserves its own warning, because the opposite advice circulates and it is genuinely dangerous.
Turning hungry cattle onto lush, rapidly growing pasture, particularly ryegrass or a legume-rich sward, is a classic route to bloat. The animals gorge, gas forms faster than it can be belched away, the rumen distends, and in severe cases the animal suffocates. Bloat can kill within hours.
The same lush spring growth also carries a risk of grass tetany, a magnesium deficiency that comes on suddenly and can be fatal. Rapidly growing grass on heavily fertilized ground is often low in magnesium relative to potassium, and lactating cows are most at risk.
Practical precautions are simple and effective. Fill cattle with dry hay before turning them out onto lush pasture. Introduce new grazing gradually rather than in one move. Provide a magnesium supplement during the spring flush, particularly for lactating cows. And watch the animals closely for the first days on any new sward.
Do Not Forget Legumes
An all-grass pasture is a missed opportunity. Legumes such as white clover, red clover, and lucerne (alfalfa) bring two things grasses cannot.
First, they fix atmospheric nitrogen through root nodules, feeding the grasses around them and reducing fertilizer requirements. Second, they are substantially higher in protein than grasses, lifting the feed value of the whole sward.
The caveat is bloat. Legume-dominant pasture significantly increases bloat risk, particularly when wet and lush. Keeping legumes at a sensible proportion of the mix, roughly a third of the sward, captures most of the nitrogen and protein benefit while keeping the risk manageable.
Note also that lucerne (alfalfa) is a legume, not a grass. It is frequently listed among “pasture grasses,” which is simply a category error, and it matters because legumes and grasses behave very differently in terms of nitrogen, protein, and bloat risk.
Grazing Pasture Versus Cutting for Hay
The species that graze best are not always the species that make the best hay.
Good hay species include timothy, orchard grass, bermuda grass, and the legume lucerne, all of which cure well and retain leaf. Kentucky bluegrass, prized for grazing sod, is generally less useful for hay because of its low growth habit and modest yield.
The broader point is that pasture rarely grows evenly through the year. Spring produces far more than the herd can eat, and then summer or winter produces far less. The surplus is not waste unless you let it become waste. Conserving the spring flush as hay or silage is what turns a seasonal peak into year-round feed, and it is the reason a pasture strategy and a conservation strategy have to be planned together rather than separately.
For farms conserving that surplus as baled silage, the quality of the wrap is what determines whether the feed value survives to winter. Silopak has manufactured silage film and bale net wrap since 2011 from premium virgin resin, holding a reliable seal for 18 months or more.
Frequently Asked Questions
Q: Is Kentucky bluegrass drought tolerant?
No, and this is commonly stated the wrong way round. Kentucky bluegrass has a shallow root system, typically 4 to 8 inches deep, and it responds to summer drought by going dormant and turning brown rather than staying productive. Its real strengths are cold tolerance and its rhizomatous growth, which lets it form a dense, self-repairing sod. The genuinely drought-tolerant cool-season pasture grass is tall fescue, whose roots reach 2 to 3 feet and which stays productive through dry spells that force bluegrass into dormancy.
Q: Is tall fescue safe for cattle?
It depends entirely on the variety. Most older tall fescue, including the widely planted Kentucky-31, carries a fungal endophyte producing alkaloids that cause fescue toxicosis. Symptoms include reduced weight gain, poor conception rates, prolonged gestation, reduced or absent milk production, heat intolerance, and in severe cases fescue foot, where restricted blood flow causes loss of hoof or tail tissue. Modern novel endophyte varieties keep the plant’s hardiness without the toxic alkaloids and are the right choice for new plantings.
Q: Can I turn hungry cattle straight onto fresh pasture?
No. This is one of the most reliable ways to cause bloat, which can kill an animal within hours. Hungry cattle gorge on lush growth, gas builds in the rumen faster than it can escape, and the rumen distends until it compresses the lungs. Fill cattle with dry hay before turning them out, introduce new grazing gradually, and watch them closely in the first days. Lush spring growth also raises the risk of grass tetany, a sudden magnesium deficiency that particularly affects lactating cows, so magnesium supplementation during the spring flush is a sensible precaution.
Q: Should pasture include legumes?
Yes, in a controlled proportion. Legumes such as white clover, red clover, and lucerne fix atmospheric nitrogen, which feeds the surrounding grasses and cuts fertilizer costs, and they carry substantially more protein than grasses, raising the feed value of the whole sward. The trade-off is bloat risk, which rises sharply in legume-dominant pasture, especially when it is wet and growing fast. Keeping legumes at around a third of the mix captures most of the benefit while keeping the risk manageable.
Q: Why does soil pH matter more than fertilizer?
Because below about pH 6.0, phosphorus and several trace minerals become chemically locked up in the soil and unavailable to plants, no matter how much fertilizer you spread. You can apply phosphorus to acidic ground and see almost no response, because the plants simply cannot access it. Correcting pH with lime unlocks nutrients that are already present in the soil, which is frequently cheaper and more effective than adding more. Always test the soil before deciding on a fertilizer programme.
Reviewed by Sue Su, Marketing Director of Silopak, on 10 August 2026. This guide has been revised to correct the drought tolerance of Kentucky bluegrass, expand the tall fescue endophyte warning, and add bloat and grass tetany guidance. It is general information and does not replace advice from a local agronomist or veterinarian.
