September 7, 2008

Pasture Basics - every farmer should know.

By Clive Dalton and Deric Charlton

This post looks at the first principles of pasture management. For further reading see the post on Top 10 Pasture Problems.

What is a pasture?

  • Pasture is a living community – intertwining plants of grass, clovers, herbs, weeds and bare ground. However, pasture plants are different from many plants – they can regrow rapidly after grazing and cutting.
  • A pasture is also a "miniature forest" containing insects, slugs, bacteria and fungi that feed on living plants and dead matter, including animal droppings.
  • The proportions of these plants vary greatly, over a paddock and over the seasons, and can be altered by grazing management.
  • Check this out by making a frame 500mm x 500mm with wire or thin timber. Throw it down at various places in a paddock and note the plants inside the frame area.
  • You will be surprised by the feed variety you offer your stock, and how the grass, clover and weed proportions vary.
  • Feeding your stock on pasture is so different to feeding livestock on grain or concentrate feed from a bag. This varies very little in nutrient value over time, but pasture offers variety – breakfast, lunch and dinner for your animals – and they prefer it that way, just like you.
  • Grazed pasture is also the cheapest feed. Silage and haymaking cost money and time, and grain or concentrates are by far the most costly feeds for livestock. And feed is about three-quarters of costs in livestock production – so the cheaper the feed, the better the profit margin (so long as it's good quality feed).
Pasture varies year-round
  • To appreciate pasture variety, try to understand how pasture plants grow.
  • They start off as small seedlings and rapidly begin to spread by branching.
  • Grasses develop branches we call tillers – leafy shoots growing from buds near the plant base.
  • Encouraging tillering is vital to keep getting top quality feed, because grass is most nutritious to stock when it is in this leafy growth stage.
  • The best way to encourage tillering is by regular, controlled defoliation by grazing or cutting for silage or hay. Note – this in not complete defoliation. You should always leave stubble to enable the plants to recover.
  • White clover and lotus, another valuable nitrogen-fixing legume, spreads by developing creeping stems. These can root at the nodes (joints) and break into new plants.
  • Once established, pasture plants remain leafy until warmer temperatures and longer days induce them to flower.
  • Seed heads appear and the plant's nutritive value decreases (helping to protect them from grazing so that they can reproduce by seeding).
  • Once seeds are produced, annual plants die off and perennials resume vegetative growth until the next year.
  • So remember that the pasture feeding value varies from day to day over the year, but is always best when the plants are leafiest. Livestock need feed variety too – grow them a menu!
The needs of your stock vary over the seasons.
  • At one time stock will need high quality feed nutrients for growth, bearing their young and for lactation.
  • They can withstand lower quality feed when dry (not lactating), mature and when putting on excessive fat.
  • Most importantly, they need feed variety to maintain good health and condition.
  • International markets are also demanding primary produce from animals raised under stress-free and sustainable conditions.
The food factory in plants – the leaves
  • The leaves are the plant's food factories – the greater the leaf area, the more food is produced.
  • Plants build up their food reserves using photosynthesis, a process that needs plenty of light and chlorophyll, the green pigment that absorbs light.
  • Plants rely on photosynthesis to take in oxygen and give out carbon dioxide during daylight. The end product is carbohydrate production.
  • Pasture plants then use these food reserves in respiration, when they take in oxygen and emit carbon dioxide. Sunlight is not essential for respiration, so it continues all the time.
  • These building and breakdown processes control the nutrient value of pastures. It's changing all the time.
  • When farm animals graze plants too low, it takes longer for leaves to regrow and resume efficient food production.
  • Animals grazing too low can also consume ryegrass endophyte toxins (those causing ryegrass staggers), which are most concentrated in leaf bases, and fungal spores in deal pasture litter, which causes facial eczema.
Food storage in plants
  • Plants store food reserves in roots, stems and leaves.
  • Roots are major food stores, so the balance between roots and shoots is very important. They are also essential for absorbing water, and some pasture plants develop deep root systems and are more drought-tolerant than those shallow-rooted plants.
  • Many leaves are needed to feed the roots, and good root reserves encourage better leaf growth.· Pasture plants can be weakened, or even killed, very quickly by excessive grazing or cutting, as the root reserves become exhausted.
  • Plants need time to recover. Ryegrass and clover are popular pasture plants because recover quickly after grazing, but lotus needs more time for recovery, so needs a longer break between grazings.
  • To build up good food reserves, allow the plant time to photosynthesise and grow its leaves.
  • Spelling a pasture between grazings is an essential part of pasture management – just like time management is essential for people in business!
Feed value varies as plants grow
  • Protein levels are highest in young pasture kept in regular tillering, and especially in pastures with good clover content evident.
  • As plants mature, their DRY MATTER (DM) content rises, but their feed quality declines.
  • DM is what's left of a plant or feed after water has been removed using a stove oven or microwave oven.
  • Spring pasture is around 20% DM and pasture at the hay is around 80% DM.
  • But the DM feed value (energy and protein) is the crucial factor.
  • These days we talk about a feed's ME – metabolisable energy. It is a measure of feed quality. Highly nutritious feeds have an ME 0f around 12, and poor quality feeds are around 6-7.
  • Protein levels fall rapidly as plants change from their leafy stage to flowering, and fibre levels increase rapidly.
  • Silage is cut when the pasture is still leafy, so is lower in fibre, but hay is high in fibre.
  • For high quality grazing, try to maintain pasture plants at the nutritious vegetative stage – when leaf content is high and fibrous seed head content is low.
Stock won't eat everything on offer
  • Just like us, farm animals have well-developed taste and smell.
  • They don't like to eat pasture contaminated by dung and urine, particularly their own.
  • They'll only eat pasture around dung and urine patches after about 4-6 weeks in normal circumstances (when they're not forced to).
  • Some farmers like to chain harrow the paddock as soon as stock are removed to spread the dung patches. This may a good idea if you have time, but other farmers say this only spreads the smell over a wider area, and it's better to leave dung alone.
  • Some animals, especially sheep and horses, are more selective grazers than others. They usually graze the most palatable plants (especially clover) before other species, and eat the most palatable, leafy plants parts first.
  • However, they also like fibre at times, and this is a natural desire of ruminants (cattle, sheep, goats), and horses, llamas and alpacas, which have a slightly different digestive system.
  • All these animals can digest cellulose, which is a major carbohydrate in plants that humans cannot digest.
  • Plants also have a fibrous carbohydrate called lignin, which is too tough for even farm livestock to digest. So they pass it through their systems.
Livestock have different preferences
  • Cattle prefer long pasture as they use their tongues to sweep grass into their mouths. The ideal is 2300-2500kg DM/ha, which is about 110-150mm high. They cannot graze too closely – below about 800-1000 kg DM/ha or about 50mm high.
  • Sheep will, however, graze much closer – down to 500-600kg DM/ha or 25mm high.
  • Deer prefer broad-leaved plants (clovers, chicory) to grasses, and leave high-endophyte ryegrass if they can.
  • Horses are patchy grazers, and prefer prairie grass to high-endophyte ryegrass.
  • Goats tend to be browsers, preferring more fibrous feed and tending to leave lush clover.
Pasture plants are different too
  • Grasses, such as ryegrass and cocksfoot, are bulky food and are high in fibre when flowering.
  • Legumes, like clovers and lotus, have three times the protein content of grasses.
  • Grazing herbs, such as chicory and plantain, offer essential minerals and even medicinal properties.
  • Trees and shrubs can offer shade and feed in hot, dry summers and pinch periods.
Let's now look at grazing systems

The tools for pasture management: #1 The Grazing Animal
  • The main tool is the grazing animal. The animal harvests its own pasture feed, and its grazing maintains pasture plants in the leafy stage.
  • Mature stock can be used to graze off pastures that have gone to head, and can be made to clean up pastures that younger animals are reluctant to eat.
  • If pasture grows out of control and produces an obvious feed surplus, then make hay or silage with it. This creates a feed store for pinch periods, such as summer droughts or cold winter spells.
  • If individual pastures are showing seed heads that stock won't eat, then top them using a mower or slasher.
  • Topping and allowing the cut material to wilt often makes it more palatable to cattle, so they'll hopefully clean it up. This often applies to some weeds too.
  • Avoid topping chicory pastures – this plant has hollow stems and rainwater collects inside, rotting the plant base.
  • Remember – the animal eating its own feed is the cheapest tool in pasture management.

The tools for pasture management: #2 Rotational grazing
  • This is the basic controlled grazing system – areas of a paddock are grazed in rotation using temporary electrified fencing.
  • Shift the electric fence regularly to allow the stock their daily ration, to meet their nutritional needs.
  • A back fence boosts pasture recovery – but water must be available to stock at all times.
  • By rotational grazing, a " feed wedge" is built up ahead of the stock, and it's easy to see which paddocks are growing the most feed and can be grazed next.
  • It's also easy to see how the pastures are growing, so decisions on the rotation length become easier.
  • Remember – shuffle grazing can be more effective, when a quicker-growing, more productive paddock can be grazed more often than those that are less productive.
  • The rotation length is the number of days it takes before the stock will be back in the paddock they have just grazed.
  • In spring, newly-calved dairy cows will be on a 20-day rotation or round, as feed is plentiful and growing fast (up to 80kg DM/ha/day).
  • In winter, when dairy cows are dry and on a lower feeding level, and grass growth is slow (around 15kgDM/ha/day), they will be on a 100-day round.
  • If pastures are not growing satisfactorily (for example, when it doesn't rain for a while), then slow up the rotation to give the pastures ahead of the stock enough regrowth time before they are grazed.
  • During this waiting time, the stock cannot wait and be starved. Use some supplement feed, such as surpluses made into hay and silage during spring or autumn flush periods.

The tools for pasture management: #3 Set stocking
  • This is where animals are kept in a paddock and left there until they have grazed the paddock to a satisfactory level.
  • Most folk on lifestyle blocks will set-stock their pastures, as it saves the daily workload of moving electric fences.
  • To the amazement of many farmers, research has shown there is very little difference in annual DM yields, between rotational grazing and set stocking, if you get things right. Please note those last few words!
  • With rotational grazing, it's easier to see what's going on behind and in front of the electric fence.
  • The trick for successful set stocking is to match the right number of animals in the paddock with the number of days you want to leave them there – and to do this for every paddock (and they usually vary in size).
  • Of course, a large paddock can be divided into smaller chunks for set stocking using electric fences.
How many livestock to graze? This is the key question!
  • If you have too many animals for your block, you'll be constantly short of feed, and stock will not perform to their potential.
  • In addition, you will need supplements in quantity, which you'll probably have to purchase; and even in spring, you won't have any surplus pasture growth to conserve as hay or silage.
  • If you have too few animals, your pastures will always be out of control. You will end up with too much hay and silage that you'll never use, and won't profit by selling it.
  • Work out an overall stocking rate for your farm, based on what you can winter – the winter carrying capacity.
  • This will avoid trouble with the law (for not providing adequate feed and running stock in poor condition). Check what livestock numbers any neighbouring farmers in the area are carrying, or seek advice from a consultant.
What to do with a feed surplus:
  • Make hay, silage or "baleage" with pasture during the spring flush.
  • Making hay in autumn is almost impossible, because shorter days are not hot enough for good drying.
  • Making autumn silage can also be tricky, because pasture can be too wet, and autumn days are not hot enough to wilt it.
  • Bring in extra stock to eat the excess pasture feed – buy them or borrow them.
  • Top any surpluses that arise through the year.
What to do in a feed deficit?
  • Feed out the hay, silage and baleage made during flush periods.
  • When trouble is forecast, apply nitrogen fertiliser at least 6-8 weeks beforehand and after some rain. Avoid applying it when it's hot and dry.
  • Sell stock or graze them off the farm
Topping: when to do it?
  • Lifestylers love riding around on machinery topping pastures.
  • It certainly makes the place look tidy for a while.
  • When topping pastures, remember you're spending money on tractor fuel and wear-and-tear.· There's always a danger that paddocks will be "scalped" – and if it turns dry, you'll have hastened drying-out, having removed any protection against the sun.
  • You could be providing the ideal dead litter in the pasture that the facial eczema fungus loves.
  • Why not use some older animals (yours or the neighbours) to clean up the surplus pasture?
Basic hazards of winter grazing
  • Concentrating stock on pastures in wet conditions will cause treading or pugging damage.
  • The pasture plants end up being pressed into the soil and their growing points are damaged.
  • It can take months for them to recover and you will also have done long-term damage to the soil's crumb structure.
  • In very wet conditions when pugging is likely, remove stock to a paddock that you can sacrifice, or put them on a race or concrete yard for part of the day.
  • Feed livestock hay to keep them busy, so they don't spend all their time walking the fences looking for feed.

"Putting and taking" stock
You can put more stock on to eat surpluses and remove them during feed deficits. It's good theory, but difficult in practice, for several reasons:
  • You will need money to buy stock.
  • You may not make money when you sell them.
  • You'll have more stock agent's commission and transport to pay.
  • You should have a reliable source of animals.
  • You may need extra land to hold them during feed deficits.

Pasture conservation 101
  • DM in feed supplements will cost you 3-4 times that of grazed pasture, and their nutritive value is usually lower.
  • If you make supplements as silage, baleage or hay, make sure they are of highest possible quality.
  • Make silage when there are 15-20% seed heads in the pasture.
  • Make hay when the pasture plants are still leafy.
  • If you do nothing and leave the pasture for deferred grazing or standing hay, its feeding value will vary enormously and will usually equate to poor hay.
  • The big advantage of making early silage is that you'll be able to return the paddock to the grazing rotation very quickly, and much quicker than if you made hay.

Summary: Pasture Grazing in a Nutshell
  • The challenge – to find the balance between maintaining good plant root reserves, maintain enough leaf area on the pasture to keep the food factory working, and still make sure that the animals' particular nutritional needs are met.
  • Keep pastures at the green leafy stage as long as possible – this is when plants provide the highest quality feed.
  • When pasture plants go to seed, feed quality drops dramatically.
  • In spring, keep control of as many paddocks as you can, and conserve any surplus feed from paddocks that are going to head as silage, baleage or hay.
  • Don't graze pastures too closely (about 30mm for most stock) as it slows recovery and may damage the plants' growth points.
  • If you graze too hard and pastures open up, weed seeds will germinate and colonise any bare areas.
  • In dry summer periods feed stock silage, baleage or hay when the stock need it.
  • Ration any autumn flush carefully, to build up a surplus ahead of the stock – to supply winter feed and to save money on supplements.
  • Avoid applying nitrogen fertiliser, just hoping for extra feed. Nitrogen fertiliser must be used strategically, so work out when to apply it to plan when the feed flush will occur.
  • Grasses and clovers will not grow when soil temperatures at 15cm depth are low ─ below 6˚C.
  • Avoid damaging pastures in winter by pugging, as this will delay growth and open up pastures for weeds to invade.
  • Develop a fertiliser policy – replace the plant nutrients removed by what you send off the farm.
  • Keep weeds under control – one year's seeding means seven year's weeding!
  • If your pastures don't contain vigorous and productive grass and clover species, plan a pasture renovation programme for the next autumn or spring.

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