Sheep Farm Husbandry – Practical feeding advice

Practical feeding; sheep feeding needs, pasture feeding: measuring pasture growth, supplementary feeding: feeding different classes & ages of sheep, feeding hoggets & lambs, ewe feeding needs, flushing, pregnancy feeding, weight of uterus and lambs, energy units, stock units

By Dr Clive Dalton

Measuring feed (pasture)

• This is where feeding sheep really starts, as pasture is the main feed you’ll be offering your flock.
• You have to be able to look at a paddock and estimate how much feed is growing in it so you can work out how many “grazing days” there are for the flock.
• It’s simply a question of when do you shift the sheep. But it’s not simple.
• Realise that not all of what you see in a “pasture” is going to be nutritious feed.
• If you look at an area of sward you’ll find grasses (some good and some not-so-good), clovers (usually all good), a wide range of weeds, bare ground and dung patches.
• The last two do nothing to make money from sheep, and the weeds may even stop grass and clover growing.
• Learn to think in terms of dry matter per hectare (DM/ha) all the time. So when you look at a paddock and you see “what’s on offer” to the stock, it will be in kg of DM/ha.
• If you want to know what is growing each day, think of kg of DM per hectare per day (kg DM/ha/day).
• So forget about the old acres and visualize hectares all the time and the DM that is there, and what extra you are getting each day, and of course how much of that DM/ha the stock will eat each day, how much they will leave and how much they will waste.
• This is the first part of “feed budgeting” where you see if the feed on the farm expressed in DM will meet the needs of the stock. You can do this in three ways:

Method 1 – Cutting and drying

• This is accurate but tedious.
• Make a metal square (as wood breaks easily) with sides measuring 0.5m. Making the sides 1m long is too big to work with.
• The area of this square will be 0.25m. (Remember half x half = a quarter). There are 10,000m² in a hectare so multiply the 0.25m by 40,000 to get the weight of pasture from your 0.25 square metre frame on a hectare.
• Throw this square at random (at least 5-6 times) walking across the paddock and cut the pasture growing inside it with garden shears or old sheep shears. The more samples the better but time will limit what you can do as it’s so time consuming.
• Weigh the wet pasture.
• Mix it up well and take a small sample and weigh it.
• Put this sample of feed into an oven at about 100°C for about an hour, or microwave on defrost for 5 minutes or until it stops losing weight.
• Weigh the sample when it is completely dry.
• Then calculate the (Dry weight/Wet weight) x (100/1). This is DM%.

Method 2. – Ruler

• Here you use a ruler to measure average pasture height across the paddock.
• It’s not a high-precision method.
• Rulers are produced by commercial companies e.g. fertiliser manufacturers.
• Equations have been worked out relating pasture height with DM/ha for spring, late spring, summer, autumn and winter.
• The ruler shows kg DM/ha.

Method 3 – Plate meter

• Go around the farm with a plate meter which are commercially available.
• It works on the simple principle of pressing down on the “pasture mass” and from using equations comparing the pressure with the cut & dry results, you can estimate kg DM/ha. The equations vary for the time of year but all these are in the instructions, or you can get them from a farm consultant or veterinarian.
• If you buy plate meter, pay the extra money for one with a small computer on it to save all the tedious calculations.
• Don’t take their readings as gospel – and never expect two operators in the same paddock to get the same readings. It’s not that precise an estimate.

Method 4 – Electronic probe

• Go around the farm with an electronic probe.
• This does the same job as a plate meter but works off electrical impulses produced by the pasture mass.
• Electronic equipment doesn’t like wet weather.
• It’s more sensitive and less robust than a plate meter and it’s also more expensive.

Method 5 – Visual assessment

• This is where you walk the paddock and estimate what’s growing by eye.
• The big advantage is that it’s fast and you have no gear to carry around.
• Accuracy depends on your experience – and as you gain more. you can become very accurate, or as accurate as you ever need to be.
• The best way is to learn is from other farmers, preferably at a group discussions when you can see how folk vary in their estimates.
• Have frequent checks with other people, or against the plate meter and probe. Or if you can face the tedium, cut and dry a few samples every now and again.

Method 6- Rapid yield mapping

• This unit built on skis is fitted behind an ATV (quad bike) and travels at 15km/hour taking readings hundreds of times a second using a swath width of 12 m. This produces around 100,000 readings per hectare.
• It’s big advantage is speed and the large number of readings it can take to iron out variation across the pasture when only a few readings are taken.

Warning

• Realise that using these methods to estimate pasture growth, (other than by the tedious method 1) will show great variation, so use your eyes to constantly check what is going on. You’ll soon see if you got things wrong, such as when you calculated the paddock should last the sheep 3 days and they eat it out in one!
• When you walk the farm to estimate pasture- walk the whole farm! Don’t walk (or ride) into the gateway and base your estimate on a quick circuit. Walk the paddock on a diagonal and if there are any areas that you know have different soils or not as well drained, go and estimate them separately to add into the total.

Conclusion

• Most sheep farmers are going to end up using eye assessment (which is mainly pasture length) to estimate feed cover so this would be the best skill to aim for.

Practical exercise

Question: How many grazing days will there be in a 5 ha paddock for 1500 ewes?

Here’s what you do:

1. Work everything out on per hectare basis.
2. Assess what the pasture cover is – assume it’s 4cm long and 1400kg DM/ha.
3. Decide what the residual will be after the sheep come out of the paddock – assume 800kg DM/ha.
4. So the sheep will eat 1400-800 = 600kg DM/ha.
5. On the 5 ha paddock the total feed is 5 x 600 = 3000 kg DM.
6. So 3000 kg DM for 1500 ewes will last 3000/1500 = 2 grazing days.
7. If you know that pasture is going to grow significantly during the two days, then you can add that in to the calculation.

Knowing how pasture grows on your farm

• Knowing how much feed your farm will grow is the key to profit. When you start off you won’t have any idea so ask a consultant or local farmer who has been monitoring feed for a while and use their figures. Or they may have district averages as shown in Table below.
• Once you have been monitoring your own farm for a while, this information will be the most reliable.
• The grass growth pattern will show a high peak in the spring, then a drop off till mid summer with a bit of an autumn flush before the winter period of slow and low, and even no growth.

Key points from the table

• Soil fertility has a massive impact on pasture growth and so does rainfall.
• There can be enormous seasonal variation around these averages.

How much feed do sheep need?

Using pasture length information.

The table below shows some information as a general guide to feeding sheep at different production levels and ages.

Key points from the table

• Note these are minimum values so always aim to exceed them in practice.
• When pastures are short and don’t exceed 5 cm in length they would generally be green, leafy and hence have high protein and energy. The challenge is to keep them like this all the time.
• The exception would be in summer when it gets dry and there was a lot of dead litter on the surface that rots away quickly with the first autumn rains.
• The ewe in late pregnancy and when suckling lambs needs the very best of pasture to meet her daily DM needs.
• Growing lambs need good pasture to allow good growth and development. The figures in the table should be minimum levels.
• The same applies to hoggets – they need to be kept growing on good feed levels.

Feeding levels for different weights of ewes

The feed needed for maintenance is based on live weight and this is shown in table below along with what happens when feed quality varies.

Key points from the table

• Poor quality pasture has 25%+ dead material.
• Average quality pasture is green leafy.
• Good quality pasture is legume dominant.
• For extra 50g/day gain (feed = 10 ME) add 30% to maintenance.
• For extra 100g/day gain (feed = 10ME) add 100% to maintenance.
• So a good round figure to remember is that a ewe need to eat 1.0 – 1.3 kg of DM/head/day of good to average quality feed to maintain herself.
• This can also be defined as holding her at a condition score of between 2.5 – 3.5. This should be your management aim during the summer period after her lambs are weaned.

Feeding for flushing and joining

• Flushing is the ancient practice of feeding ewes on a “rising plane of nutrition” 2-3 weeks before the ram goes out, and a couple of weeks during joining to encourage better ovulation rates.
• What is a rising plane? Research shows that gains of 0.5 -1.0 kg/head/week can be useful targets, but it depends so much on the actual weight the ewes are at to start with.
• Good target (minimal) weights for ewes are:
• Pre-mating 53kg and Condition Score of 3-4.
• Mating – 57kg for 2-tooths and 60kg for mixed-age ewes.
• Ram removal – 55kg.
• Ewes can gain 0.5-1.0 kg liveweight during the first few weeks of joining if good green leafy feed is available. Ideally they should be going into 5-6cm of pasture (2200kg DM/ha) and leaving 3cm pasture (1500kg DM/ha).
• This is not often possible on hill country, especially in dry autumns when 2-3cm-long feed would be more likely to be available.

Feeding for pregnancy and lambing

• Good feeding in the first half of pregnancy is vital for good placental growth, and if this is neglected, it cannot be put right by good feeding in the second half of pregnancy.
• This means a good pasture cover for lambing is around 1200–1300kg DM/ha but for really high production 1400–1500kg DM/ha should be the target.
• The other target is a minimum of Condition Score 3 for lambing.
• It’s a good aim to feed ewes 3 weeks before lambing on the same feeding level as they will get as soon as they have lambed.
• The table below shows how feeding levels needed at different stages of pregnancy.

Key points from the table

• Clearly the ewe’s feeding needs go up rapidly as the ewe approaches full term.
• These values assume the ewe’s single lamb is 4kg birth weight, and the twins would be around double this.
• For triplets add an extra 75% to the twin values.

Weight of uterus and lambs during pregnancy

The scales only tell you the total weight of a ewe which includes what’s inside her, so as the lamb/lambs get heavier, the ewe could be getting very skinny and losing weight rapidly. This is where condition scoring is a good guide to her state of health. The table shows some general figures used to account for the uterus full of lambs and fluids called the “gravid” uterus.

Feeding growing sheep (lambs)

• Young growing sheep are the ones that really need plenty of high quality feed that includes all the important nutrients.