How to Calculate How Much Dry Food You Have in Your Pasture

Pasture assessment for absolute beginners

Owning a large amount of land is an incredible responsibility. If you do not know what you are doing you may very well make some serious mistakes before you have a chance to learn how to do things correctly.

You cannot just do nothing with the land. You will either need to lease it to people who know how to manage the land (although when you do not know what is required to manage the land it is actually impossible for you to know if what the leasee is doing is correct!) or you will need to manage the land yourself. If you choose to manage it yourself you will need to ensure that you keep some plant growth in the paddocks to prevent the topsoil blowing or washing away. The top soil is not very deep and contains the required nutrients that enable plants to become established and grow. Once it is gone it is very difficult to establish any plant life. A bare paddock and a very windy day are a disastrous combination. You will also need to keep your weed burden down so that weeds do not take over your pastures and leave you without any stock feed. Also, your neighbours will not thank you if your weed seeds are forever blowing into their paddocks. You do not want to be driven out of town by an irate group of farmers. You will need to select the plant species you wish to grow and then ensure they can become established and stay established by eliminating the competition from the undesirable weed species that will forever be trying to invade your paddocks. You are going to need advise and help from the very start of your venture if you are going to succeed. You do not have the luxury of spending ‘a few years’ learning how to farm while your paddocks turn to dust!

I cannot advise you on what pasture you need to grow or what chemicals you need to spray to control your weeds. You are going to need advice from specialists who know your area. I can advise you on whether or not the pasture you have growing on your property now is adequate to meet the nutrirional requirements of your stock. That is what I will attempt to do in this chapter!

I am not an agriculturalist or agronomist. When we first bought Morilla we knew nothing about pasture assessment or any other aspect of farming or agricultural life. By the time we left we knew a little bit more thanks to hours of research. I am not an expert by any stretch of the imagination, and do not know much about pasture management beyond pasture assessment. But as the quality of the pastures you have on your property now will determine how you feed your stock and how many stock you can accommodate, I think it is a fairly important skill to learn. You do not want your stock to become malnourished and lose condition before you realise something is wrong!

This is an attempt to simplify the science of assessing your pastures so the lay person can understand the basic principles. There is little more disheartening that picking up a book on pasture management that assumes some level of prior knowledge and quickly becomes confusing to the totally inexperienced.

The following advice is to help you assess whether you have adequate pastures for your livestock’s dietary needs. If you don’t have adequate pastures, you will be wanting to improve them. To do this I recommend you seek advice relevant to your farm’s location, from either a local agricultural expert or your neighbouring farmers Many pasture grasses and pasture mixes are available and you will need expert advice on which pasture grasses would grow best in your area. Making a mistake can be very expensive and leave you without adequate feed for your animals and a dry paddock that will be prone to erosion and topsoil loss.

Unfortunately, when explaining pasture assessment to you experts may talk about FOO, DM, MJ ME/kg DM and DSE, and you may be left a little confused. Alternatively, some of your neighbours may actually not really understand the science of pasture assessment themselves, having relied on ‘assessing the pasture and stock by eye’ for most of their farming careers. Just because farming has become a highly scientific occupation, it does not mean that all farmers are highly scientific or understand the science behind the things they do. Their ability to assess pastures by eye after years of experience is a skill which is impossible to teach to you. You will need a more reliable method of assessment! The following information will help bridge the gap between the novice and the experienced farmer or the highly scientific agricultural expert. This will hopefully arm you with an adequate understanding of the science behind assessing pastures and animal feed requirements in order to keep your stock healthy and well fed.

Sheep and cows are grazing animals, and pasture provides the most cost effective way to feed your animals. In fact, without the ability to graze these animals on pasture, the profits from their production would be greatly reduced. Sheep and cows like to eat grass, keeping busy nibbling along most of the day. It fills them up, provides them with their nutritional requirements and gives them something to do. It would be rather boring to live in a paddock if there was nothing at all to do but sit about. Sheep and cows can live on grass alone providing the grass is nutritionally adequate to meet their dietary requirements. So this is where it all gets a bit complicated. How do you know when the grass is adequate, and when the grass is inadequate?

There are three things you will need to know to determine whether you have adequate pastures to feed your livestock numbers.

Your pasture’s composition- what plants make up your pasture

The quantity of food in your pasture, measured as ‘dry matter’

How much your livestock will need to eat to maintain good health

First of all you will need to know:  What is growing in my pasture?

Determining pasture composition

Pasture composition refers to the different types of plants growing in your paddock and the frequency (percentage) of the pasture each identified plant makes up. It is important to know because some plant species are more beneficial that others, some can cause illness in your stock if they eat them at the wrong time (such as some ryegrasses) and some plants are poisonous to your stock.

Before you put any stock into your paddocks ask a friendly neighbouring farmer to help you identify any poisonous plants you have in your paddocks. It is fairly important to be able to identify poisonous plants found in your area as well as invasive weeds that you will need to control.
You can look on your local agricultural department website for information and photographs of problem plants in your area. It is worth taking the time to study these plants and learn how to identify them so you will be able to recognise them if they appear in your paddocks. Noxious and invasive plants need to be kept out of your paddocks.

The following method is a simple way to assess the frequency of individual plant species in your pasture so you can establish exactly what is growing in your paddock and in what proportion.

Cut a 30cm length of 1cm-thick dowel, and hammer a nail into one end

Throw the stick ahead of you at random intervals while walking across the pasture in a W shape (start from the top left hand corner of the paddock and walk down to the bottom of the paddock at an angle of about 25 degrees, walk back to the top middle of the paddock, down to the bottom of the paddock and finally end up at the top right hand side of the paddock- to make the shape of a W as you walk)

After each throw, identify and record the plant species that is touching or immediately below the nail point at the end of the thrown stick

Record the results as perennial pasture species (eg Phalaris), annual pasture species, legumes, weed types, or bare ground.

Repeat 25 times.

Add the number of hits for each species or group and multiply by four (to convert to number of hits out of 100 because the number of throws is 25 and 25 x 4 = 100) to give you a percentage.

How do I know what the plants are?

If you like you can refer to agricultural pamphlets on how to identify pasture grasses and plants or you can take photos and identify the plant on the internet. Try your local agricultural department website. Again it is probably easier for the novice to ask a neighbouring farmer to help you identify the plants growing in your pasture. You can also ask an agricultural consultant or an agronomist to help if you do not have a friendly or reliable farming neighbour who is willing to help you.

A warning about leasing your farm

The farmers who initially leased our farm from us were very helpful in identifying the poisonous plants on the part of our property where we were keeping our livestock. Unfortunately, they did little to control any of the invasive weeds on the land they were leasing from us. They also bought more varieties of new weeds onto the property when they bought their livestock and machinery into the paddocks and by the time their lease expired the pastures on the farm had deteriorated considerably. Of course for the first two years we were so inexperienced that we did not realise that the leasees were not taking adequate care of the property. We noticed by the third year when large areas of new types of plant growth we had not previously seen on the property became very obvious. The weeds were introduced in the first year of the lease, established themselves in the second year and quite literally took over large sections of the farm in the third year. Needless to say, we did not renew the lease with these farmers! Although they knew we were inexperienced and obviously took advantage of the situation, it was ultimately our responsibility to know what was happening on our land. And we did not. If you plan to lease your farm, get an agricultural advisor to check your property regularly so you will stay informed of what is happening to your land.

It is worth remembering that even though you have leased your land out to someone else, they cannot legally ruin your property! They are obliged to manage your property properly and not allow it to deteriorate from overuse and under care! Keep a close eye on your leasees and seek advice regularly from people you trust as to how the leases are managing your land.

Next, you need to find out how much food (dry matter) is in your paddocks

How do I determine my pastures quality?

The two main things that determine the quality of your pasture are: herbage mass and digestibility.

Herbal Mass

Herbage mass is the quantity of the pasture present and is measured in ‘kilograms of dry matter per hectare’ or kg DM/ha. It is measured as ‘dry matter’ which is what your pasture would weigh without its moisture content. So even if your pasture is green, you will be measuring it as if it were dry. It just means that you have ‘x’ amount of pasture minus any moisture. Water has no nutritional value, so is not measured.

Measuring herbal mass

But how do you measure the dry mass per hectare, you ask? Well there are a few ways.

You can employ specific pasture measurement instruments like a sward stick, a plate meter or pasture probe.

Sward Stick

A sward stick is a ruler that measures the length of the grass from tip to ground. To use the sward stick method you will need to walk in a ‘W’ pattern through your paddock taking random measurements of your grass as you go. Place the sward stick on the ground and measure the height of the blade of grass. You will need about forty samples, avoiding taking samples in areas where grass will be unusually low (animal tracks) or unusually high (near a leaking trough). Then you will need to calculate the average of the forty readings. (The average is the sum divided by the count)

The sward stick method uses ‘optimal grazing heights’ to determine you pastures’ quantity, with length of grass determining how long you can graze your sheep in a paddock. For instance you put your ewes into a paddock with blades of grass at 8-10 centimetres high, and when the average length is reduced to 4-5 centimetre high you move them out, as the optimal height will drop after this and the sheep will overgraze your pasture and may not be able to meet their nutritional requirements.

 The optimal height of the grass varies for sheep at different stages of production and development. The height of grass recommended for grazing lambs is 6-8 centimetres or higher. The optimal height of grass for dry ewes is 4 centimetres or higher and the optimum height for lactating ewes is 5 centimetres or higher. If you choose this method, ask the supplier for all the relevant information on how to use your sward stick and how to apply the data to your feeding regime.

Plate Meter. 
You can also use a plate meter. The plate meter consists of a flat round disc on a pole. The operator places the pole on the ground and the grass pushes the moving plate up the shaft of the pole to measure the height of the grass. The meter's plate is calibrated for weight and area. During use the plate is supported by the pasture. The taller and denser the pasture is, the further off the ground the plate sits. The bottom counter records the position of the plate relative to the shaft, totaling the readings as each sample is taken. A sample counter at the top of the meter is used to record the number of samples taken in each paddock. Again, you will need to take about forty or fifty measurements randomly as you walk.

Before you start you need to set the top counter of the rising plate meter to 0 and record the opening reading (A) on the rising plate meter before you start. While walking through the paddock make sure to record the number of readings taken by clicking the top counter. After walking through the paddock, record the number of readings taken (C) and the closing reading (B) on the rising plate meter.

Use the following equation to calculate grass cover (KG DM/ha).

Closing reading (B) - Opening reading (A)   x  140+500kg DM/ha
             Number of readings (C)

To calculate the quantity of grass present in the whole paddock multiply the DM yield of each paddock by the area of the paddock in ha. Now don’t panic, because you don’t know where the 140 + 500 came from! I will attempt to explain.

   The plate meter measures the compressed height of pasture. Each of the clicks represents 0.5cm of compressed height therefore a reading of six clicks represents a compressed pasture height of 3 centimetres

   The (scary) equation as you saw it

   The average compressed pasture height x 140 + 500= kg DM/ ha. This breaks down as the readings from plate meter x the multiplier + the adder = kg DM/ha.  

   What does the equation even mean, anyway?

   THE equation changes the compressed height (i.e. clicks) to a kg DM/ ha. This equation is a guide and not an absolute measure of quantity as the DM composition will change with type of pasture grown and due to seasonal variations.

   The plate meter equation is a regression equation. You may wish you had paid more attention during statistics so you can easily comprehend this. I sure wish I understood it and I passed statistics with a high distinction!

The adder is where the regression line bisects the vertical axis- which means it is the DM yield when the plate meter has a reading of 0. The multiplier is the slope of the regression line. The multiplier accounts for the increase in DM yield for each increase in plate meter reading.

But don’t worry if you don’t really get it. You don’t have to. Just know this:

For the winter formula above (clicks x 140 + 500) the DM yield when the plate reads 0 = 500kgDM/ha and for   every 0.5cm or click of compressed height measured by the plate meter there is another 140kg DM/ha..

   Range of the multiplier

   115 — when grass is growing the fastest , is lush and moist and has a low DM

   140 — this is about the average and is therefore the best fit for the whole season

   185 — used in very dry conditions of slow growth, such as drought. The grass is dead and dry and, of course, will have far less moisture and a higher DM.

 Use the one number for the adder for simplicity and convenience, and adjust the multiplier to suit your current pasture conditions. It can be much more complicated than this- check out the internet for ‘pasture equations’ and you can make it as complicated as you like! The equation of average compressed height x 140 + 500 is the best used for most situations and makes the data produced the easiest to understand. Remember it is a guide not an absolute measure!

Electronic pasture probes

These measure dry matter of green material only. They are quick, easy to use and usually fully automated. Their accuracy declines if there is any free moisture present in the pasture such as after rain or heavy dews.

They are the most expensive of the three groups. You are usually able to download the data to a computer and then all the calculations are done automatically.

Assessing by eye

Once you become an old hand at pasture management and have the years of experience required to ‘just know’ what is happening in your paddocks, you may be able to fairly accurately assess your pasture DM by eye alone.

Confused and still feel you know nothing about what dry food you have available?

The final method is for all of us who know nothing and need it to be as basic as it possibly can be. This is probably the most accurate measurement tool, as long as it is carried out correctly.

Cutting, Drying and Weighing Pasture Samples

You will need to choose sample areas that are representative of the pasture being assessed. Try to get a good overall representation of what is actually growing in your paddock.  The number of samples taken will depend on the different pasture species growing and the density of the growth of these pastures .The more samples taken the more accurate the estimate will be.

Here’s what you do:

Clip selected areas measuring 0.25m² of your pasture to ground level. Remove soil from clipped pasture grasses.

Weigh each sample you cut. You need this measurement for your calculations.

Mix your samples together thoroughly and remove 200grams of pasture from the mix.

Dry the 200gram sample either in a conventional oven (preheat oven to 100ºC, place sample in heat proof dish) It will take 24 hours for the sample to dry completely in a conventional oven.

Alternatively dry in a microwave. Loosely spread sample on a microwave proof container with no lid. Place the sample in the microwave. Also add a glass filled with water to the microwave. Microwave on high for five minutes, weigh the sample then return it to the microwave for another two minutes on high. Remove and weigh the sample again. If the sample weighs less than it did the time before, put it back in the microwave for a further two minutes. Keep doing this until the weight of the sample remains unchanged from one zapping to the next. Now it is at a stabilised dry weight. This can take up to 20 minutes in a microwave.

How to calculate herbal mass per hectare from your dried pasture sample

Once you have found the dry weights of the samples, the kg DM/ha can be calculated.

Here is an example:

Area of pasture clipped = 0.25 m²

Weight of undried clipped sample (from one 0.25 m² area) = 400g or 0.40 kg

Dried weight of 200 g undried sample (taken from all samples after thorough mixing) = 50 g

Dry matter %

= (50/200) x 100

= 25% DM

Pasture mass/ 0.25m² (cut area)

= 0.40 kg (fresh sample weight) x 0.25 (20%DM)

= 0.1 kg DM/0.25m²

Pasture mass/ha (kg DM/ha)

= 0.1 x (10,000/0.25) [given that 10,000m² = 1ha]

= 4,000 kg DM/ha

Easy!

There is one final thing to note: Some farmers make a distinction between herbal mass and ‘Food on offer’ or FOO. With this distinction, the herbal mass is assumed to not include the lowest 0.5cm parts of the grass, as sheep will often not eat this, unless there was nothing else. This assumption means that on average 300kg DM/ha (0.5cm) is unavailable to sheep. FOO refers to all the grass from the ground up. The calculations I have shown above are for all the grass from the ground up and so would be called the FOO rather than the herbal mass by some farmers!

Digestibility

Digestibility means the portion of feed that is not excreted as faeces and is the part of the feed that a sheep can use to supply its nutritional and metabolic needs. It is the portion that is digested and absorbed by the sheep as nutrients. Not all of the energy in feed is available for your sheep to use for nutrition. If feed matter is not able to be broken down by the sheep’s digestive system, its potential energy will be lost in the way of faeces. Some energy is lost as heat from the rumen during the digestive breakdown of the feed, or as methane and carbon dioxide. The remaining usable energy, called metabolisable energy or ME, is absorbed and used to meet the metabolic needs of the sheep. Metabolic needs such as growth, activity, pregnancy, lactation and functioning of all body systems.

Metabolisable energy is measured in megajoules of metabolisable energy per kilogram of dry matter (MJME/kg DM). The higher the MJME/kg DM of the feed, the more energy will be available to meet the sheeps’ nutritional needs. Feed with 10 MJME/kg MD then each kilogram of dry matter of that feed contains 10 megajoules of metabolisable energy available for use by your sheep.

Like all living things, sheep requires a certain number of megajoules of energy to meet their nutritional requirements. This number will vary according to the sheep’s needs- pregnancy, lactating, rapid growth, exposure to cold, excess physical exertion, recovery from injury and ill health. If sheep do not consume enough energy to meet their needs they lose weight. If sheep consume more energy than they require they will gain weight and store the excess energy (joules) as fat. Just like people. As a livestock owner you have a responsibility to keep your sheep in good health, so it is up to you to ensure their nutritional requirements are met. At the same time, you do not want to over feed your sheep as this can eat into your profit. It is a balancing act.

Different feeds have different MJME/kg DM, and these values have been worked out in a laboratory somewhere by clever scientifically minded people. You do not have to work these out, thank goodness, and can refer to many websites, or your agricultural consultant, or stock feed specialist to find out what these values are for the feed you intend to give your sheep.

Basically the dry feed will consist of carbohydrates (about 75%), which include soluble carbohydrates (simple sugars), storage carbohydrates (starches) and structural carbohydrates (fibre) which are made up of the plant cell walls and give the plant structure. The dry feed also has fats and oils (which are usually less than 3%), protein of varying percentage, and vitamins and minerals.

Relationship between pasture growth stages, pasture digestibility and available energy from the pasture

There is a basic average assessment that can be made of pasture’s digestibility and MJ ME/kg DM based on the life stage of the plants in the pasture.

Green and growing

Plants that are green and in active growth have the highest digestibility of around 75%. The energy (MJ ME/kg DM) is between 10.8 and 11.6. That is, for every kilogram of dry matter you have in your pasture, each kilogram will supply 10.8 to 11.6 megajoules of energy.

In the late vegetative stage when the grasses are still green but the plant is no longer growing actively, the digestibility drops to around 70% and the energy drops to 9.9- 10.8 MJ ME/kg DM.

Both of these stages allow the animals grazing to reach high production, or to have the maximum energy available to meet their energy requirements. This is when livestock can be pregnant, or lactating or actively growing (lambs and calves) and the energy requirements for these activities will be met at no detriment to their general health.

Early flowering and starting to dry

Once plants start to flower through to mid flowering (when the plant is partly green/ partly dead) , the production level drops to moderate production. Here the animal is able to maintain their general health and spare a little extra energy to growth, recovery from injury or illness or possibly pregnancy and lactating as long as there is ample feed available.

When plants start to flower the digestibility is around 65% and the energy is 9.1-9.9 MJ ME/kg DM. At mid flowering the digestibility is down to 60% and the energy is 8.2-9.1.

Late flowering and drying off

By late flowering, when the plant is in full head or seed and has mostly dried off, the digestibility is 55% and the energy is 7.4-8.2 MJ ME/kg DM. This is called the maintenance phase because it is sufficient energy to maintain your stock in general good health but not energy enough to allow your stock to be pregnant, lactate or grow quickly (as required by lambs and calves) without those activities being detrimental to the animals overall health.

Dead, dry leaves and stalks

Once the grass has been reduced to dead and dry leaves and stalk, or worse, just dry stalks, the digestibility has plummeted to 45% and the energy is down to 5.7- 6.5 MJ ME/kg DM. This is not enough to maintain stock health and at this point your stock will begin to lose weight and condition. Also, as the digestibility drops it causes the animal to feel full sooner and stop eating. Therefore, the animal is eating less of a less nutritious feed and this compounds the problem.

Finally you need to determine how much dry matter each head of your stock needs to consume each day

How much energy (MJ ME/kg DM) do my livestock need?

In Australia the standard unit used to determine how much energy livestock require is the DSE, or Dry Sheep Equivalent. This unit is not the same globally. The DSE is specifically Australian to meet our general conditions.

Dry Sheep Equivalent

The DSE refers to the energy required to maintain a 50 kg wether (castrated male sheep) at a condition score of between 2 and 2.5. This has been determined, by some agricultural scientists somewhere in Australia, to be 5.8 MJ ME/kg DM per day

So a 50 kg wether needs to eat 5.8 MJ ME/ kg DM every day to maintain a condition score of 2.5.

If you search the internet or read reference books you will find that, with a little variation here and there, the following applies:

50 kg Pregnant ewes need the equivalent energy as 1.3 DSE

50 kg Lactating ewes with a single lamb need the equivalent energy of 2.5 dry sheep

50 kg Lactating ewes with twins need the equivalent energy of 3.5 dry sheep

60 kg rams need the equivalent energy of 1.4 dry sheep

70 kg rams need the energy equivalent of 1.7 dry sheep

On average you need to add or subtract 1 % for every kilo your sheep is over or under 50 kilograms (so a 40 kilo gram dry sheep needs 0.9 DSE instead of 1.0, and a 60 kilogram pregnant ewe needs 1.4 DSE instead of 1.3.

So how does that actually help me figure out what I need to feed my sheep?

Well, it doesn’t really. It is just a way of standardising the MJ ME required by sheep and other livestock. 1 DSE is 8.5 MJ ME per animal per day.  So two DSE is 17 MJ ME per animal per day. Once you know that 1 DSE = 8.5 MJ ME then you can work out the rest. It is easier to remember that your lactating ewe requires 2.5 DSE than it is to remember she needs 21.5 MJ ME per day. It simplifies things.

Actual MJ ME required each day by each head of stock:

So what are the actual MJ ME per head of stock per day. For sheep it is:

40 kg dry sheep- 7.6

50 kg dry sheep 8.5 – the standard measurement

60 kg dry sheep- 9.7

50 kg pregnant ewe – 11.5

50 kg lactating ewe- 17

Weaner less than 20 kilograms- up to 4.5

Weaner 20 kilograms- 4.5

Weaner 25 kilograms -5.7

Body condition scoring 

Body condition scoring is used to evaluate your feeding program and determine the need for changes. Body condition is a better indicator of condition than weighing, as it allows you to assess whether your sheep are very thin, in ideal condition or obese.  Having a sheep’s weight alone tells you very little of value, as sheep’s ideal weights vary quite a lot (just as humans’ weights vary considerably between one individual and another). You will have no idea if the weight of each sheep represents its ideal weight or not. Weight alone, in a way, is quite meaningless when it comes to assessing whether your sheep are in ideal condition.

A body condition score estimates how much fat and muscle are present on each animal. Both the vertical bone protrusion (spinous process) and horizontal protrusion (transverse process) of the loin are felt and used to access body condition scoring. It is a not a precise science as it is open to individual interpretation of what is felt under hand. It will give you a fair idea of the general condition of your flock.

The system uses a scale of 1 to 5, with 1 being an emaciated sheep, 3 being a sheep in average condition, and 5 being an obese sheep. Half scores can be used if you like.

Most sheep have body condition scores between 2 and 4. No sheep in your flock should have a condition score below 2.  A sheep with a condition score of 1 is a starved or sick sheep and needs to have its conditions improved straight away to bring it back to health, or be humanely destroyed if it is terminally ill. Farmers are not exempt from animal cruelty and neglect laws. If the conditions in which you keep your sheep are examined by outside agencies and considered unsatisfactory, you may find that as well as a fine and possible prison time, you may be prohibited from ever keeping livestock again. It is also not ideal to have any sheep with a condition score above 4. An obese sheep is less likely to be fertile and therefore becomes unproductive, whilst at the same time consuming excess food that is costing you money! Remember that a ewe's body condition score will change throughout her production cycle. The body condition score can be used at any time to determine if your feeding programme is meeting the needs of your sheep. The two most important times to body condition score ewes are prior to breeding and at weaning.

Body condition scoring

    Emaciated-  Spinous processes are sharp and prominent. 

Transverse processes are sharp; one can pass fingers under ends. It is possible to feel between each process. Loin muscle is shallow with no fat cover.

 Thin- Spinous processes are sharp and prominent. 

Transverse processes are smooth and slightly rounded. It is possible to pass fingers under the ends of the transverse processes with a little pressure

  Normal-  Spinous processes can be fely but are smooth under your fingers. 

T       Transverse processes are smooth and well covered, and firm pressure is needed to feel over the ends.
 Loin muscle is full with some fat cover.

  Fat- Spinous processes can be detected only with pressure as a hard line across the back of the animal. 

Transverse processes cannot be felt.  Loin muscle is full with thick fat cover.

 Obese- Spinous processes cannot be detected. 

T       Transverse processes cannot be detected.
 Loin muscle is very full with very thick fat cover.

    

Pasture Allowance

Pasture allowance describes the amount of pasture allocated to livestock and is expressed as kilogram dry matter per head per day (kg DM/head/d). The following equation is used to calculate pasture allowance:

Pasture allowance = ((pre-grazing pasture mass – residual pasture mass) x paddock area) ÷ (number of animals x days grazing)

For example, if you grazed 2500 ewes on a 10 hectare paddock for 20 days with a pre-grazing pasture mass of 2500 kg DM/ha and a target residual pasture mass 800 kg DM/ha then pasture allowance would equal:

= ((2500 – 800) x 10) ÷ (500 x 20)

= 17000 ÷ 10000

= 1.7 kg DM/ewe/day