The starting point for maintaining a healthy, productive flock is the selection of sound ewes and rams before the beginning of the breeding season. By carrying out a careful examination of resident animals and culling those with obvious problems, and by purchasing sound replacement animals, the flock will have the potential for peak production.
If purebred or pedigree sheep are being kept, particular breed points should obviously be taken into account if the intention is to show or sell animals. When rams are being purchased, look for any records of performance, such as estimated breeding value (EBVs). These records measure traits such as growth rate and carcase quality, and enable the selection of above-average performing rams, the use of which has been shown to add extra value per lamb when sold for meat. EBVs are sometimes available for ewes, with lambing percentage and mothering ability usually the most important criteria.
The main points to check are:
- each animal’s condition score
- the teeth
- the feet and legs
- the reproductive organs of the ram
- the ewe’s udder.
Fig. 95 It is easy to see that this ewe is too fat. She may have been barren, or have reared only a single lamb. If the whole group is in this condition they should be kept on short grass to avoid any more weight being gained before tupping time. If only a few are too fat it is not of particular concern.
Condition Score
The technique for condition scoring has been described in Chapter 2. Ewes retained from the previous breeding season should have about three months between weaning and tupping, over which time their body condition can be improved if they are thin after rearing lambs. Rams remaining from the previous season are often given little attention until near to the next breeding season, and may also be too lean. Since it takes six to eight weeks to gain one body condition score, nutrition must be improved in good time in order to achieve an optimum condition score at tupping time. Good grass is usually sufficient, but if grass is of poor quality or in short supply, extra nutrients can be supplied by providing feed blocks or a small amount of concentrates – although this obviously increases costs.
Purchased replacements may not arrive on the farm until shortly before tupping, as many breeding stock sales are not held until September. It is therefore particularly important to check condition, as there will be little time to alter this. Be careful to avoid rams that have obviously been pushed heavily with extra feed: they may be over-fat, unfit and of poor fertility. This is particularly true of ram lambs grown fast for sale in their first autumn.
Fig. 96 Even though this ewe has more wool, it is possible to see that she is lean and hollow. Such sheep require several weeks of good grazing in order to be in adequate condition at tupping time.
Fig. 97 These hill rams are on good grazing in preparation for tupping time. Putting ewes on this type of grazing before tupping is called ‘flushing’.
Fig. 98 Be careful of buying rams that have been fed heavily for show or sale. They may be fat rather than fit, and if they lose weight rapidly when put with ewes, their fertility is likely to suffer.
Fig. 99 These hill ewes on moderate grass are being supplemented with molasses’ buckets prior to tupping.
Teeth
Sheep have incisor teeth in their lower jaw only, which they use for nibbling grass by grasping it against the dental pad in the upper jaw. They also have cheek teeth (premolars and molars, six upper and lower on each side) which are used for grinding up food, most importantly during rumination (cud-chewing). Examining the incisor teeth is the most common way of telling the age of a sheep (see Chapter 2), and of assessing their state.
Fig. 100 This one-year-old sheep (she has one pair of permanent incisors) has a short lower jaw (undershot), so that the teeth meet the dental pad too far back. She may have difficulty grazing properly.
Fig. 101 The mouth of a two-year-old sheep (two pairs of permanent incisors). At first sight it appears healthy, but closer examination reveals some recession of the gums, particularly around the left central permanent incisor. This will probably loosen and be lost prematurely.
Fig. 102 A full-mouthed ewe with long, narrow teeth that are likely to become loose and lost prematurely.
Fig. 103 An old ewe, but she still has all her incisor teeth. She also has an ulcer on her gum below the teeth. This is quite common, and is usually caused by trauma when grazing rough vegetation. This is the sort of lesion that could be misdiagnosed as foot and mouth disease during an epidemic.
Fig. 104 An old sheep whose incisors have worn very short, probably as a result of grazing grass on very abrasive soil. Providing her molar teeth are healthy and she is in good body condition, she might go through another pregnancy successfully.
Fig. 105 A broken-mouthed sheep. The remaining incisors are very sharp and have caused an ulcer above the dental pad in the top jaw, making it painful to graze.
With older sheep, it is very important to assess the health of the molar teeth. This is rarely done since it is difficult, and painful for the sheep, to open the jaws to view the teeth directly. It is also risky to try to do this because the teeth are extremely sharp and fingers risk being badly chewed if inserted into the mouth. Instead, it is possible to gain a fairly accurate impression of the state of the cheek teeth by feeling the jaws, checking for thickening or disparity in the shape of each jawbone. Then by feeling through the cheeks, gross abnormalities or displacement of the cheek teeth can be detected. If you haven’t tried this before, feel the jaws and cheeks of a healthy young sheep – this will give you an idea of what normal jaws feel like – before checking older sheep. Infections of the tooth roots lead to abnormal thickening and rounding of the jawbones. Loosening or loss of cheek teeth leads to displacement or overgrowth of the remaining teeth, making chewing difficult and painful, and results in loss of body condition.
Fig. 106 This sheep has obvious swelling in her jaws; this is due to molar tooth disease and will prevent her eating properly so she should be culled.
Fig. 107 A ram dribbling saliva, which indicates pain on chewing as a result of molar tooth disease.
Fig. 108 A piece of cud or a ‘quid’ which has been dropped, indicating the sheep had difficulty chewing.
Fig. 109 Feeling and comparing the jaw bones to detect abnormal thickening.
Fig. 110 This ram has very thickened mandibles indicating advanced molar tooth disease. From the green staining, you can also tell that he is dribbling cud, another indication of difficulty chewing.
To Cull for Tooth Problems?
Sheep with less than perfect teeth are always at risk of not being able to eat sufficient to maintain adequate body condition. Incisor teeth are easy to examine, so sheep with missing incisors often get culled. However, it is the molars that really matter. The health of the incisors does not necessarily reflect the health of the molars, and vice versa, and a sheep that has lost the odd incisor may manage perfectly well providing the molars are healthy.
By contrast, a sheep with all its incisors but with molar tooth problems will struggle to maintain condition. Ewes like this are very likely to become thin in late pregnancy and to succumb to metabolic problems such as twin lamb disease. This is why it is so important to check all mature sheep thoroughly before the next breeding season. In the commercial situation, if in doubt about the teeth, cull! Make sure they go to a slaughter market if you do not wish them to be bought by someone who thinks they will take the risk to get another lamb crop. Although some sheep farmers make a speciality of buying broken-mouthed ewes to breed them again, it is very risky if they don’t have experience of managing older sheep, and can end in disaster with excessive ewe and lamb losses.
However, people who keep pedigree or pet sheep may not wish to cull them at the first sign of tooth problems. In this instance, common sense must be used, and if it is possible to give affected sheep individual attention, ensuring that they get enough easy-to-eat feed, they will often survive to a ripe old age – pet sheep of twelve to fifteen years old are not uncommon. If the stage comes where body condition is being lost and the sheep is showing signs of pain when chewing, welfare needs to be the first priority, and the sheep should be humanely destroyed.
Fig. 111 A ewe with an obviously thickened mandible; she has had a tooth root abscess which has burst, leaving a scar. This indicates severe molar disease.
The Feet and Legs
Little attention has been paid by many breeders in the past to foot and leg conformation in selecting breeding sheep. Sound feet and legs are particularly important for rams, which must be able to remain fit and active for several tupping seasons and have a lasting influence on any offspring retained for future breeding. Individual ewes obviously have less influence through their offspring (unless they produce breeding rams themselves), but it is still worth paying attention to feet and legs to ensure a long productive life with the minimum of time required to be devoted to foot care.
Good leg conformation means having a well shaped leg ‘at each corner’, with the sheep standing squarely on each. Commonly seen problems include front legs with ‘knock knees’, excessively straight hind legs (over-extension of the hock joint) and dropped fetlocks.
Fig. 112 Rams are expensive to buy, so make sure they have sound legs and feet.
Fig. 113 This Suffolk ram has a well shaped hind leg, with normal hock and fetlock joints and a neat foot.
Fig. 114 This Herdwick ram has short, strong, well shaped legs and feet to enable him to scramble around his natural rough, mountainous environment.
Fig. 115 This Texel ram has excessively straight back legs with over-extension of the hock joints. This puts a lot of stress on the joints, which may develop arthritis. He also has a rather arched back indicating possible spinal arthritis. His ability to mate with ewes has to be questionable.
Fig. 116 This Beltex ram also has very straight hind legs and shows the highly developed muscling characteristic of this breed.
Fig. 117 This animal shows poor hind-limb conformation, with the lower part of the legs and feet turning inwards.
Fig. 118 This ram has very sloping pasterns so that his fetlocks are almost touching the ground.
Fig. 119 This ewe has perfectly shaped hooves which are unlikely to overgrow and need trimming.
Fig. 120 Slightly longer claws, but they are still well shaped. Some people think that white horn is softer than black and therefore more prone to developing defects, but there is little or no scientific evidence to support this.
Fig. 121 This is a poorly conformed foot, with the outer claw much narrower than the inner. Claws like this tend to grow long and are then prone to cracking.
Fig. 122 In this foot the inner claw is curving inwards and the outer claw is angled incorrectly, so that the outer wall is not being worn away so has become abnormally long.
Fig. 123 Well shaped, sound claws that are unlikely to overgrow.
Fig. 124 A badly shaped foot: the larger, inner claw is rotated so the medial wall is under the sole. This has also caused the outer wall to deviate and overgrow. This sheep will never have a normal foot however skilfully it is trimmed.
Fig. 125 A foot with very poor quality soles. The feet are soft and excessively worn so that the normal wall that edges the sole has been worn away. It looks as though this sheep has been kept on wet concrete with very little bedding so it is difficult to know if the foot would ever return to normal if kept in a better environment.
Fig. 126 An interdigital growth, a fold of skin that has developed between the claws. These are quite common and cause lameness, as they get infected and cause pain. Animals that develop these should preferably not be used for breeding replacements as there may be a genetic predisposition. However, as the growths only develop as animals get older they may be difficult to avoid in practice.
The Reproductive Organs of Rams
However good a ram may be as regards his appearance, breeding, EBV if available, teeth, legs and feet, if he is infertile or subfertile it is a complete waste of money buying or keeping him. Ultimately a ram can only be proved to be fertile if he gets ewes safely in lamb, but there are some simple checks that can be carried out to reveal any obvious problems. If you are checking rams at sales with a view to buying, treat them gently – remember other people may be interested and therefore they may be examined many times. The main checks as well as condition are ‘teeth, toes and testicles’. We have already addressed condition, teeth and feet above, so the remaining check is to gently palpate the scrotum and testicles. At sales this can be done simply by squatting behind the animal and feeling between the legs without necessarily turning the ram over.
With rams that are already resident on the farm a more thorough examination can be carried out. This should be done at least eight weeks before they are due to go into the ewes so that condition can be adjusted if any are too lean, foot problems dealt with, and any obviously substandard animals removed and replaced if necessary.
Turn the ram over and sit him comfortably on his behind. Some rams, particularly fat ones, find it difficult to breathe in this position and get distressed after a short time, so carry out the examination as quickly as possible if this is the case. First look at the prepuce and penis. If there are sores or scabs on the prepuce these should be treated with antiseptic cream or antibiotic spray. Occasionally such sores can be caused by bacteria or the orf virus, which can be transmitted to the ewes, so make sure they are healed before the ram is used.
Fig. 127 This ram’s scrotum and testicles look normal, but can easily be checked with him in the standing position.
Fig. 128 It is easy to see from a distance that this ram’s right testicle is much smaller than the left. Do not buy a ram like this, as he will be less fertile than is normal. In particular do not use a ram with this defect for pedigree breeding, as the abnormality is likely to be heritable.
Fig. 129 This ram is far too thin and will not be ready for tupping time. He has small testicles and will produce very poor quality sperm. Sperm take six weeks to develop and mature, so even if the ram miraculously gained weight rapidly, he would still be producing poor quality semen for some time.
Fig. 130 It is possible to see from a distance that the skin of the scrotum of this ram is abnormal. This is scrotal (chorioptic) mange.
Fig. 131 This ram has a large sore on his prepuce. It is advisable to treat it with an antiseptic cream or antibiotic spray, and it is safer to wear disposable gloves to handle it.
Fig. 132 In this ram the penis is partially exteriorized, but is still hidden under the lining of the prepuce.
Fig. 133 The end of the penis is exposed, showing the prolonged narrow tube at the end of the urethra (the urethral appendage, vermiform appendage, worm).
With practice it is possible to exteriorize the penis, but if this can’t be done, don’t worry. It is rare to find an abnormality except for the floppy pink urethral process (sometimes called ‘the worm’) at the end of the penis, which may occasionally be found to be missing. This narrow tube is an extension of the urethra, which carries urine from the bladder, and its main purpose is thought to be to spray semen over the cervix of the ewe during mating. However, its absence does not usually mean that the ram loses his fertility, and many rams have continued to work effectively having lost the process either accidentally or as the result of surgery to treat obstruction with small bladder stones.
When examining the scrotum and testicles, look first to see that the scrotal skin is of normal pliable appearance. Scrotal mange is an increasingly common problem, and is recognized by characteristic areas of thickened skin. Other problems that may be encountered are scabby areas at the bottom of the scrotum caused by Dermatophilus congolensis, the bacterial cause of mycotic dermatitis (lumpy wool). Any infection of the scrotal skin which raises the temperature of the testicles can cause infertility.
Fig. 134 The skin of this ram’s scrotum is normal in appearance and has no excess wool cover.
Fig. 135 The scrotum and testicles of this young ram appear normal. There is some wool on the end of the scrotum, but not enough to cause a fertility problem. If there is a lot of wool on the scrotum it can cause the testicles to become too hot, so should be carefully trimmed away.
Fig. 136 This ram’s testicles look and feel normal, but the scrotal skin is abnormal. Note the areas of thickened skin (scrotal mange), which are due to a mite called Chorioptes bovis. This mite is similar to Psoroptes ovis, which causes sheep scab, but it is more difficult to treat.
Fig. 137 Chorioptic mange also affects the lower parts of the legs and is very irritating. This ram is rubbing his foot on the wire to relieve the itching.
Next, look at and palpate both testicles and the attached epididymes. The testicles should be of approximately the same size and consistency, and each should have a recognizable tail of epididymis. These are golf-ball-sized structures, which you should be able to feel attached to the lower end of each testicle, and their function is to store sperm while they are maturing. If the testicles or epididymes are of noticeably different size or consistency, this may signal a problem with fertility. Another problem occasionally encountered is a scrotal hernia, where some abdominal fat or even intestines are lying alongside one of the testicles. If you have any doubts you should consult your vet who can carry out a more thorough examination, including the collection and examination of a semen sample.
Other Problems in Rams
Brisket Sores
These are seen most commonly in heavy rams, but can occasionally be seen in fat ewes or wethers. They can be caused by an incorrectly fitted ram harness, but such sores can be seen on animals that have never worn a harness, in which case the explanation is that they are probably pressure sores caused by lying about on hard ground. Whatever the cause, they usually do not heal up – in fact they often get larger with time, even if treatment is attempted. They also attract flies in summer, resulting in the sheep lying down for even longer, thus creating an even worse situation. Never buy a ram that already has a brisket sore as his useful life will be limited, and be prepared to cull affected animals.
Fig. 138 Measuring scrotal circumference gives a good idea of whether a ram is likely to be fertile. The scrotum of an adult ram in the breeding season should measure at least 36cm; that of ram lambs and adults outside the breeding season will measure rather less.
Fig. 139 The tail of epididymis is clearly visible as a separate structure at the lower end of the testicle.
Fig. 140 The head of epididymis lies at the top of the testicle and is not as clearly defined as the tail.
Fig. 141 This ram has an obvious hypoplastic (smaller than normal) left testicle. The right testicle looks to be of normal size, but appears to have a very small tail of epididymis (the small round structure at the bottom right of this testicle). This indicates that he is likely to be of low fertility, or completely infertile.
Fig. 142 A ram with only one testicle. He should not be used for breeding as the condition could be hereditary.
Fig. 143 This ram has an enlarged and firm tail of epididymis, which is detected by feeling and comparing each side.
Fig. 144 A vasectomized ram – the scars from the operation can be seen in the skin of the neck of the scrotum.
Fig. 145 A brisket sore caused by a badly fitting harness. It can be very difficult to get such wounds to heal up.
Head Wounds
Rams kept in groups often fight with each other in order to establish a social order, and some sustain head injuries during these clashes. Even if minor, the injuries can be a problem in summer as they attract flies: head flies cause great irritation and the affected animals rub their heads, making things even worse. Protecting them with a synthetic pyrethroid pour-on is usually necessary. In the case of larger head wounds these often become infected and smelly, attracting blowflies which lay eggs; the maggots then hatch out within a few days. Again, a pour-on will protect.
Fig. 146 Injuries may be severe if horned rams fight with hornless ones.
Fig. 147 Rams can injure or kill each other through fighting.
Fig. 148 This ram has a head wound which will need protecting if it is the fly season. Sometimes quite large, horn-like (keloid) growths appear at the site of these injuries, but they are easily knocked off during further fighting.
Infections of the Skin of the Head and Ears
Crusty, scabby or granulomatous lesions on the head or ears of rams in particular are quite common. These are often caused by infections such as ringworm or the orf virus so should be taken seriously. Do not buy a ram with this type of infection, and if resident rams develop them, have them investigated by your vet. Both diseases can affect people, so use disposable gloves if handling them.
The other increasingly common disease seen particularly, but not exclusively, in terminal sire breed rams is caseous lymphadenitis (CLA). This bacterial disease causes abscesses to develop in internal and external lymph nodes, very commonly in the parotid lymph node situated just below the ear. This is usually an incurable disease, which, while rarely killing infected animals, is disfiguring and a general nuisance once in a flock. Examine any ram you are intending to purchase carefully, particularly around the head, as abscesses may burst and heal leaving little evidence other than a small scar. This is a disease you do not want in the flock if you haven’t already got it (see Chapters 3 and 6).
Fig. 149 The large, scabby area on this ram’s head was the result of ringworm infection. Ringworm is sometimes acquired from buildings that have housed infected calves.
Fig. 150 The granulomatous lesion on this sheep’s ear could be a skin tumour, or it could be caused by the orf virus. Rams can develop chronic orf infection around the head when fighting wounds become infected.
The Udders of Ewes
As far as selection of breeding ewes is concerned the most important factor is udder health: will they be able to produce milk from both sides of the udder in order to feed their lambs? Newly purchased young replacements can generally be assumed to have sound udders, so it is ewes which have previously bred on the farm that should be most carefully examined. Ideally any ewes that were found to have blind teats at lambing, or that suffered from mastitis during lactation, should have been identified by a permanent mark, for example an ear tag, so they could be removed after weaning. Some ewes will develop mastitis, which is undetected whilst they are suckling lambs, or, more commonly, will develop chronic mastitis after weaning.
Fig. 151 This ram has a CLA abscess in his parotid lymph node, which lies between the base of the ear and the angle of the jaw.
Fig. 152 The scar is where an abscess has burst and healed. This will become increasingly difficult to spot as the scar contracts and the hair regrows.
To find these animals, the pre-breeding check should include a careful feel of the udder and teats. Each half of the udder should be soft without obvious lumps, abscesses or abnormally firm tissue. Note that sometimes the fibrous division between the two halves of the udder can feel quite firm and thick, but providing the udder tissue itself feels normal, this is probably not of concern. As well as checking the udder tissue, the teats should be gently palpated to detect those which have become obstructed as a result of chronic mastitis – even though the udder may feel relatively normal, the teat will feel as though it has a fibrous cord running down it and this should always arouse suspicion. These are the ewes which, if not spotted, will be those that lamb down with only one functional teat. Of course in the case of pedigree or pet ewes, the decision may be to keep them, but at least future problems of lack of colostrum and milk can be planned for.
Fig. 153 A normal, non-pregnant ewe’s udder. Note the dark, waxy secretion in the gland in the fold of skin adjacent to the teat on the right, and less obviously on the left. This is normal. The amount and colour of the wax varies.
Fig. 154 This ewe has four teats. It is quite common to find extra teats, but they are not usually functional. In this case the extra pair is quite well developed and may produce some milk.
Other Problems with Purchased Sheep
There is a long list of important infectious diseases that can be accidentally introduced into a previously uninfected flock with bought-in sheep, be it one ram or 500 breeding ewes. These diseases include sheep scab, lice, footrot, contagious ovine digital dermatitis, enzootic abortion, maedi visna, Johnes disease and many more (see Chapter 1).
Fig. 155 These warty lesions are quite common on ewes’ teats, developing where lambs’ sharp teeth have caused abrasions. They are of no concern as long as they are not infected.
Fig. 156 This ewe has a small abscess discharging pus. Is it just in the skin, in which case it will probably heal up and not affect milk production, or is it connected more deeply to the udder tissue?
Fig. 157 The left half of this ewe’s udder is enlarged, with obvious abnormal lumps which are abscesses. At the lower end of the udder a scab indicates that one abscess has already burst.
Fig. 158 This ewe has had gangrenous mastitis and has lost one half of the udder, leaving a large scar. She should be culled.
Fig. 159 This ewe has also had gangrenous mastitis, but the dead udder tissue has not yet sloughed off. She cannot be sold through a market until this is well on the way to healing.