January 10, 2009

Sheep Farm Husbandry - sheep identification and recording

Sheep, husbandry, breeding, recording, identification, methods, tags, permanent & temporary identification, age marking, new methods, electronic tags, DNA profiling, check lists, practical tagging advice, in wet & dry weather, tagging lambs, recording live weight, sorting sheep into similar groups.

By Dr Clive Dalton

Ewe with permanent plastic tag, farm ear mark, and age mark

You cannot do any worthwhile breeding to improve flock performance unless all animals are identified, and this ID must be unique so that no two animals have the same identity. No system of ID is ever perfect, as there are always problems with permanent tags being lost (e.g. pulled out on fences), and temporary marks on wool fading or being shorn off.

A unique identity
  • The best way to form a unique identity is to use an individual number along with the sheep’s year of birth.
  • So for example 123/05 is number 123 born in 2005. There may be other sheep numbered 123, but they won’t have been born in 2005.
  • The best ID method is a brass ear tag put in the lamb’s ear at birth and then supplemented with a plastic tag later when the lamb’s ear grows bigger and stronger. Some breeders put a brass tag in either ear to reduce the chance of lost identity.
  • There is much less chance of a brass tag coming out or fading than a plastic tag. However, recent advances in plastics have greatly reduced the fading of numbers and colours in plastic tags from the intense sun radiation in New Zealand.
  • So each year get your tags (both plastic and brass) to run from Number 1 to however many lambs you expect to have, and add the year born on to each tag. With brass tags, get your name punched on the third side too.
  • Visible plastic ear tags also have many advantages for general management such as using different colours for age groups.

Good permanent ID methods Brass tags

This brass tag is too near the head, and should be in the top of the ear where it's easier to read, and is well clear of shearer's combs. Fortunately Border Leicesters have clean heads.
  • These have proved their worth over decades in New Zealand sheep.
  • Which ear? Always put the brass tag in the sheep’s left (near) ear, on the top, as this is the one held by the shearer when coming up around the neck.
  • Where to put it? Punch it into the top of the ear, about a third of the way along from the head toward the tip, leaving room for the ear to grow and the tag to remain in a readable position.
  • If you put it too near the head it will grow into the skin folds, and you’ll have to fight the sheep every time to read it, and the animal will remember the experience.
  • Always read brass tags from left to right to avoid confusing 66 with 99.
  • Keep all tagging equipment disinfected during and after use. Check for any ear infections and festering a couple of days after tagging.
  • Brass tags come on sticks with a rubber band on the end, to stop them slipping off and getting out of numerical order when you drop them!

Very small plastic tags
  • These are like a numbered pliable plastic band that bends around the edge of the ear when clinched together. They can be put in a lamb’s ear at birth without causing it to droop and malform it, and little festering occurs if you keep your gear clean.
  • They come in a range of colours and you cannot read these from a distance.

Medium plastic tags

  • These are smaller and less expensive than the very large tags.
  • Put them in the sheep’s left (near) ear to help the shearers.
  • They are still too heavy to put in young lambs and even lambs at weaning.
  • They are easier to read than the small plastic bands, but you’ve got to be up fairly close to the sheep to read them.
  • They are an ideal intermediate tag, but farmers don’t like the expense and bother of replacing them so will wait till the sheep is big enough for a large tag.

Large plastic tags

  • These are “flag” type tags that you can easily read from a distance of 3-5 m and come in a range of bright colours.
  • Put them in the sheep’s left (near) ear to help the shearers.
  • You can have them numbered or you can write your own numbers on with a supplied pen containing ink that does not fade. Some fading is inevitable in New Zealand’s intense sun.
  • Don’t put these in lamb’s ears until they are at least 5 months old as they are too heavy for the lamb’s small ear and it will pull it down and permanently disfigure it. Also more festering can occur.
  • Punch them in the middle of the ear about half way along avoiding the two main ligaments and the veins.
  • Keep all tagging equipment disinfected during and after use. Check for any infection and festering a couple of days after tagging.
  • Always put the same number on the plastic tags that is on the brass or small plastic tag, and it’s a good idea to use different colours for each year’s crop of lambs to help sorting age groups later.
  • Don’t use old plastic tags as it will only cause confusion.
  • You can cut bits out of the edge of plastic tags with ear marking pliers to denote groups or ages.
  • There are also plastic tags that slip through a punched hole can be used to identify age groups. These are put in the top or bottom edge of the ear and can be easily removed but they cannot be read from a distance.

Poor permanent ID methods

  • Self-piercing aluminium tags were once popular but have not shown any great advantage over the brass tags which once the ear heals are generally trouble free.
  • Tattoos. Here sharp pins in the shape of numbers and letters are held in special pliers and punched into the middle of the sheep’s ear between the ligaments. Black pigment is then rubbed in to the wound. It’s important to put plenty of pigment on the pins and make sure the sheep do not move when it first feels the pain. Don’t flinch, and grit your teeth once you close the pliers.
  • You are very lucky if the ID is readable for much of the sheep’s life, and a vivid imagination is always useful when trying to decide on the ID!
  • Ear notches for numbering. Here you use the top, end and bottom of the ear to punch a single or double notch made with special pliers that cut a piece out of the ear. Each position represented a numeral and you can build up multiple-digit numbers by combinations of notches. It’s not used in sheep these days and is used in pigs where ear tags get eaten! It’s always a bit brain taxing to work out the code in a hurry as you have to do mental arithmetic on each ear.

Ownership and age marking
  • Ear notches for ownership. Farms can have their own mark which used to be registered with the Ministry of Agriculture and Fisheries and was useful if sheep got lost or stolen (assuming thieves would not alter it). MAF no longer registers farm ear marks.
  • National age marking system. Here notches are used to indicate year of birth, mainly in big commercial flocks. You will find diagrams in the small notebooks and diaries available from stock agents and meat companies.
  • Three positions are used on the right (far side) ear of the sheep – (i.e. the left ear when looking at the sheep’s face from the front).
  • Be consistent and always use the right ear for the age mark.

Other temporary ID methods
  • Numbers can be made with raddle on both sides of the sheep. They should be at least 200mm high and be readable from 10-15 metres away. They work best on short-wool sheep and may last for half a season before fading. Using raddled numbers and marks is a good idea for a temporary ID of multiple lambs.
  • Putting lots of raddle on the wool is not good. Here are some tips when using an aerosol raddle so you use all the can and get value for money:
  • Shake the can well before use.
  • Hold it upright when using otherwise the propellant will be used up before the paint.
  • Use very sparingly.
  • Squirt the nozzle near the required spot and only make the smallest dot possible (the size of a 10c piece when dry).
  • Store aerosols in a cool place out of the reach of potential graffiti artists.
  • Marking udders to ID lambs to ewes. The trick is to put plenty of coloured raddle around the ewe’s teats and when the lamb suckles it leaves a raddle mark on its head. It works surprisingly well and is useful if you have an untagged mob of ewes and lambs and you want to draft them into two smaller mobs. It’s also useful if two mobs have got mixed and you want to separate them making sure the ewes get their correct lambs back. It’s sometimes called the MUM (marked udder method). It works with lambs as young as 3 weeks old.

Chalk raddle

  • You can get chalk raddle in a wide range of colours.
  • It’s useful for short-term marking such as by the meat company lamb drafter.
  • It usually washes off in about a week.
  • It’s messy stuff to handle but a farmer has invented a plastic holder for the chalk sticks to keep your hands clean and the raddle dry when not in use.
  • Only used approved products.

Neck tags

  • These can be used for temporary ID in flocks at lambing where you don’t want to catch the ewe to read her brass tag and cause disturbance, but they are a lot of work.
  • You need a check list of neck tag against brass tag.
  • They can be made of all sorts of materials from tin and plastic lids to proper engraved Formica and you need the letters to be at least 40mm high.
  • Tying the cord the correct length is important otherwise the sheep gets the front legs though when grazing.
  • It’s important to remember to remove all neck tags before shearing.

  • You can use stick-on or tie-on luggage labels to mark sheep for short periods such as sales or when clients are selecting rams. There’s always a risk of them getting rubbed or torn off.
  • A clever farmer invented two-part paper labels (called tally tags) on an elastic band that goes around the sheep’s neck. You then tear half the label off at the middle perforation so one number stays around the sheep’s neck and the other half can go with the wool. This allows you to go back and find the sheep (that were not permanently tagged) that had the highest fleece weights after shearing.

Coloured clips

  • Coloured plastic clothes pegs can be used when picking rams.
  • Gripping paper clips can also be used on the wool – and not on the ears!

Coloured wire twisters

  • Use short lengths (about 100mm) of pliable coloured plastic wire that can be threaded through a brass tag and both ends twisted together.
  • A wide range of colour combinations can be used and old electrical cable is a great source of wire.
Nature’s raddle
In an emergency what do you do when you have caught a sheep (usually after a struggle) and don’t have a marking raddle with you? Look round for some fresh dung to mark her face or if you can reach far enough around, there’s always a fresh supply at the back end!

New ID methods

Electronic tags

  • These are now being used in some sheep breeding flocks where large amounts of performance data are being recorded.
  • At the moment they can only be read when close to the sheep.
  • The potential is here for the animal’s complete data to be stored in its ear tag and act as a “passport” to record its complete history, such as feeding and health treatments and which farms it has been on.
  • This is being driven by the need to track animals in disease outbreaks and concern over food safety and the need for “traceback” from plate to paddock.
  • Costs of electronic ID will be easily accepted by breeders who keep detailed performance records and indeed it could help them, but it will pose problems for large-scale commercial sheep farmers.
  • Put them in the sheep’s left (near) ear to help the shearers.

DNA profiling
  • DNA profiling can be used where individual ID of lambs at birth is not possible.
  • Birth date is obtained by shedding off un-lambed ewes so the birth day is known for each paddock of lambs when they are docked.
  • Lambs are tagged at docking (3 weeks old) and blood samples taken for ID profiling at a special laboratory.
  • As the DNA data builds up in a flock, the parent’s ID of any lamb can be determined to a very high degree of accuracy.
  • Some labs use 6-7 genetic markers which breeders have found is not as accurate as manual recording. Only using 10-14 markers gives a high degree of accuracy.
  • Using DNA markers, it has been shown that 25% of twins had been sired by different rams – something that would have been unknown before DNA profiling.

Practical recording tips
New Zealand sheep farmers, shepherds and research technicians over the years have shown amazing innovation in developing practical ways to make field recording easier. The following are some of them:

Plastic tagging adult sheep

  • Pick a good dry day; avoid wet and humid days.
  • Do the tagging as a special job. Don’t incorporate it with a variety of other tasks.
  • Make sure everyone concentrates to avoid errors. Quieten any barking dogs.
  • Avoid general chat and make sure the person who is reading the tags has a good clear voice. A loud high-pitched voice is ideal as you can hear it above the other yard noises. Don’t let smokers read tags as the cigarette stuck between their lips all day reduces their diction, as well as their long-term health prospects!
  • Dip the tagging pliers into disinfectant after every sheep.
  • Hold the sheep firmly during tagging so pliers don’t slip half way through the job. This is not such a problem with today’s quick release pliers.
  • After tagging about 10 animals, turn them out to see if the tags are in a good readable position and not too near the head. You should be able to read the numbers at 3-5 metres away.
  • It’s nice to be consistent and put the plastic tag in the left (near) ear along with the brass tag to help the shearers. Some farmers don’t like this and put the plastic in the right ear – knowing that if a shearer hits it, there will be no damage to the gear compared to hitting a brass tag. Whichever is your choice – be consistent for the shearers’ benefit.
  • One idea (if you can afford the time) is to punch the holes in the ears and let them heal, free from the irritation of the tag. Then go back again about a week later and put the tag through the hole which will be a painless operation. It’s not practical when handling large numbers of sheep.

Brass tagging adult sheep

  • This is tough job. The ears of the sheep are tough and punching the hole with the special pliers causes pain so sheep need to be firmly held by one person while the other does the punching.
  • Then with the sheep in a foul demeanour you have to put the tag through the hole and squeeze it up correctly. If you botch this part and have to open the tag and redo it, that sheep will never forget you!
  • Put the tag in the top of the left (near) ear about a third of the distance from the head.
  • Dip the pliers in disinfectant after every sheep.
  • Watch for infections for a week after tagging.
  • Have plenty of sticking plasters handy as you will knock a lot of skin off yourself in this exercise!
Tagging lambs at birth
This is the most challenging part of sheep recording, as you can’t leave the job for another day (unless there is storm conditions) and remembering all the points made above about lamb and ewe behaviour at lambing. Shepherds and technicians developed many tricks over the years to get the job done – and here are a few of them.

In fine weather
  • Start early in the morning (just after daybreak is ideal) and work your way around the paddock tagging lambs as you go.
  • If there are groups of ewes that have all lambed in the same place – you will need to attend to them first as there will be a high risk of parentage errors.
  • On the way to the ewe note her number incase she clears off, and grab the lamb or lambs and hold them between your knees. You can do this kneeling on the ground or sitting on your backside using your leggings for insulation.
  • Use a light fishing (landing) net with collapsible handle to catch lambs, especially twins and triplets and hold them together during tagging.
  • If the ewe runs away (which is likely if she’s a two-tooth), hold a lamb by the back leg and let her see it. If the lamb does not bleat – you blare like a lamb to attract her back. This is a necessary part of the art of shepherding and practice and frustration makes perfect!
  • Tag the lamb or lambs and complete any other tasks.
  • Take out the record book and enter the data.
  • Before you let the lamb/lambs go, double check the tag numbers in the lamb or lambs’ ears and the ewe number. If there is any doubt about parentage – clearly record this fact.
  • Check the unused tags to make sure you are still in sequence and some have not been lost. Try not to drop the tags so they get out of order.
  • Don’t do the recording in bits, e.g. enter the tag number after tagging each lamb, etc. Do it all in one go at the end so it’s a big advantage if you have a good memory.
  • Let multiples go away together incase the ewe takes off with one lamb and you have to chase her with the others.
  • It used to be recommended if there were a lot of ewes that had lambed together to go in and spot mark the multiples so you got them correctly recorded with their dam when you started tagging, but farmers with high fertility flocks say they have no time to include this extra chore in their routine.
  • If you have a dog, make sure it’s under total control at all times. Make sure it doesn’t’ take off to eat afterbirths and disturb the sheep.

In wet weather
  • If it’s really wet, then keep away until it stops raining as you’ll do more harm than good. Hope that it stops raining in 24 hours because after that the lambs will be very mobile and harder to catch.
  • If it’s only showery, then tagging can proceed, remembering that punching holes in wet ears risks more infections than with dry ears.
  • Carry a towel around your neck to dry your hands before writing in the record book.
  • Keep the book inside a plastic bag and write inside there.
  • Use a dark pencil as ballpoints don’t like wet paper.
  • Use note books with waterproof paper if available.
  • Don’t risk a tape recorder incase of malfunction.
  • Use a palm-held computer inside a plastic cover – if you can trust its reliability.
  • If there is any doubt about parentage of lambs – record this fact.

Docking at birth

  • In some recorded high-fertility flocks run with minimal labour, docking is now done at birth to avoid the work and disruption of docking later.
  • There have been concerns on animal welfare grounds about the shock of docking newborn lambs, and that it will increase mismothering as one lamb may lie down and the mother take off with the others.
  • Experienced shepherds find that newborn lambs show less reaction to having rubber rings on tails and testicles than older sheep, and mismothering has not been a problem.
  • Where scabby mouth is a problem, they can be vaccinated at birth too.

Recording kits

  • Shepherds have come up with some great ideas over the years to hold all their recording gear.
  • Examples have been modified builder’s aprons or bags with plenty of compartments for tags, pliers, notebook and veterinary supplies.
  • Also a large flap to keep all the gear dry and which also serves as a desk top in the paddock for the notebook or to sit on when the ground is wet and cold.

Tagging lambs when older

  • When farmers have adopted minimal-shepherding systems, lambs have to be tagged later when they are difficult to catch.
  • Accuracy of parentage is usually quite good, as the ewes have had plenty of space for lambing being set stocked and spread out.
  • It is possible to set up a pen like a docking pen and drive ewes into it with their lambs (singly or in groups) and tag them. It’s a slow and tedious job.
  • ID can be done at docking as described above but can be much more of a disruption unless you have a slick well-organised team, and are prepared for docking to take longer.

Recording live weight

Good lighting and concentration with no surplus
chatter is important
to avoid mistakes when tag reading and recording
  • A set of scales is an essential piece of equipment these days for large flocks, but can always seem expensive for a small flock. Small farmers should consider joining with neighbours to share the cost or borrow scales from their vet clinic.
  • Today’s electronic scales consist of two weigh bars and a platform that needs to stand on a firm base in the yards. The readout unit can be put anywhere such as on the ground, rested or hung on the fence, or hand held. It can do calculations and provide readouts such as the current weight, weight gain since the last weighing, average for the mob and the range (highest and lowest) and store all the data.
  • For individual animals that you can lift, stand on the bathroom scales and get someone else to read the dial while you hold the sheep. Remember to subtract your weight!

Check lists
  • With the best will in the world, when reading tags you’ll end up with missing numbers and duplicates that are always hard to sort out.
  • The key is to have a check list which is simply a sheet with a list of numbers from 1 to 100 or 1 to 1000. As each tag number is read, put a line through that number on the check list which proves it has been read.
  • Then as soon as a duplicate number appears, you can double check the number to see if it is the correct one, or the previous one was wrong. You may be able to see at the end from the numbers missing where the error was in reading the tag.

Common causes of errors in recording

  • Misread numbers, especially on brass tags because of poor eyesight.
  • People reading tags with poor diction or while smoking.
  • Transcribing numbers where the number is read correctly when called out, but the digits are reversed when it’s written down. Some people are very prone to doing this and don’t know it – and will argue that they didn’t do it.
  • The other variation of the above is to see the number but shout it out with some digits exchanged. Again some people have this problem and don’t know it. And they will argue too!
  • For both the above problems, insist the tag readers or those who write it down repeat it.
  • Poor writing in record books with blunt pencils or ballpoints in the rain.
  • Failure to double check at frequent intervals.
  • Failure to stick to a set routine e.g. when tagging at lambing time.

Sorting sheep into similar groups
You may want to divide sheep into groups that are similar for accurate comparisons. These could be to compare different animal health products or feeding levels. Another good reason is to compare the progeny of different rams in a progeny test.

The process is called “randomisation”, where you select the individuals at random without bias for each group. If you don’t do this properly the end result can easily be due to the bias in the original groups. Here are some simple ways for a farmer to do it:
  • Put the sheep through the race and draft them off one each way. If you only have two or three-way drafting then you’ll have to run the remainder of the flock through again if you want more groups.
  • Be careful with this technique as often the biggest sheep push their way through first and the small ones end up at the finish, so when finished have a good look at the groups for any obvious bias.
  • It’s a good idea to take out the very small and the very large ones and leave them to the end,hoping that you may not need to use them. If you have to include them, toss a coin or throw a dice to decide which group they go in to.
  • If there are different age groups in the mob, this could introduce a bias of live weight so it’s a good idea to randomise animals within age groups.

Recording fleece weights for selection

  • In past years, when wool was worth much more than it is today, selecting hoggets on fleece weight was a very worthwhile option.
  • It was highly heritable, fairly simple to record and high hogget fleece weight was a good indicator of lifetime wool production.
  • Not many farmers would do this now, and in any case hogget fleece weight has a high genetic correlation with hogget live weight, there is no need to bother.
  • The exceptions would be breeders of fine-wooled sheep where wool is still a major part of their income.
  • Wool is easy to weigh – especially with modern electronic scales and a few cardboard or plastic boxes.
  • The challenge is to weigh the wool at shearing and keep the best sheep, without slowing up the operation and affecting the shearers’ earnings.
  • This is now history, and for the benefit of historians as it’s unlikely to be ever done again, these were the ingenious tricks used. But miracles are supposed to happen so the information below could be useful one day!

Where sheep have no ID of any kind

  • Here the sheep have to be marked when they are still on the shearing board, as it could easily slow up shearing and you have to pay more for that.
  • Use “tally tags” on an elastic band that goes around the sheep’s neck and one half tears off and goes with the wool.
  • Stick-on labels don’t work on newly-shorn greasy wool.
  • Using an aerosol raddle to number the sheep before release by the shearer is too messy.

Where sheep have permanent ID
Many sheep are now tagged on commercial farms to aid management. Here are some methods used to record fleece weights of hoggets.
  • Someone reads each tag when the shearer starts on the sheep and writes the number on a good quality label with a soft-lead pencil.
  • Read the tag number at this time as the sheep’s left ear is sticking out neatly as the shearer bends to do the belly and crutch.
  • This label is then laid on the shearing board in a safe place beside the sheep.
  • The fleeco picks up the tag and then the fleece which is then put on the scales. The person on the scales writes the weight on the label and puts it into a section of a box depending on its weight range.
  • You can organise a box into sections for high (keep), medium (reconsider) and low (cull). Or you can be more sophisticated and have sections for weight ranges to produce a normal distribution at the end of shearing, on which you can make the final decisions.
  • If you write the numbers from the labels into a permanent record, the labels can be reused with a line drawn through the last weight.
  • Plan to have at least a couple of people doing the tag reading and writing numbers on labels for 4 shearers who will be doing around 60 sheep/hour each. It’s important that the recorders are not overworked as concentration falls and errors are made.
  • If the recorders are well up with the job, there are always other quick jobs they can do while waiting.
This material is provided in good faith for information purposes only, and the author does not accept any liability to any person for actions taken as a result of the information or advice (or the use of such information or advice) provided in these pages.

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