Chapter 4 MANAGEMENT OF BREEDING FLOCK

4.1 Improving breeding efficiency

Breeding efficiency is a major component in the overall efficiency of sheep production. Usually the best basis for any type of sheep production is the native (indigenous) animal. Under poor extensive conditions long term breeding efficiency is achieved at a lower reproduction rate; prolificacy is not desirable. However, under intensive conditions breeding efficiency (prolificacy, frequency of lambing and weaning percentage) should be increased. The genetics of the native breeds may be improved by selection or crossbreeding with other breeds characterized by higher prolificacy and longer breeding season.

Practical methods of selection include selection of ewe lamb replacements born as twins or born as singles from younger ewes and producing higher milk yields than the average milk yield of the flock and the selection of twin born rams or rams from ewes with a high level of twinning throughout their lifetime and which have a higher post weaning growth rate than the average post weaning growth rate of the ram lambs in the flock.

The desirable traits in a crossbreeding system in additon to improving breeding efficiency are higher milk yield, improved growth rate, feed efficiency and market desirability of lambs and better adaptability of ewes and lambs to the environmental conditions. To avoid inbreeding; mating is confined to individuals that have no common ancestor nearer than one great grand-parent.

All ewes in poor condition, dry ewes which were not pregnant after the mating period, ewes with low maternal instinct, non-functional udders or with extremely large teats, or suffering from chronic diseases, should be culled. Ewe lambs that fail to breed in the same breeding season with other ewe lambs should also be culled. Rams with limited fertility and sex drive, suffering from lameness or any chronic respiratory disease should be replaced with young rams.

4.2 Early breeding of ewe lambs

Early breeding of female lambs is an important method of intensifying sheep production in the self-replacing flock because it can increase the annual flock output, reduce the unproductive phase and thus overhead costs, facilitate selection programmes and also increase total lifetime productivity. Early breeding of well managed and adequately nourished ewe lambs has no detrimental effects on their subsequent performance and reproductive efficiency.

The important principle to bear in mind is to keep the lambs growing and gaining weight after weaning so that by breeding time they will be sufficiently mature physically to mate successfully. First oestrus is affected by age and body weight which in turn are influenced by the breed and nutrition. Female lambs are kept separately from ewes until lambing. Excessive feeding in late pregnancy should be avoided in order to reduce the incidence of dystocia. During the last two months of pregnancy the level of energy intake should be between that of a mature ewe carrying a single lamb and one carrying twin lambs.

If early breeding is not practised feeding should be adjusted to low levels in order to achieve the desired liveweight at breeding time.

4.3 Management at mating

Good planning for mating results in a short lambing period which allows efficient scheduling of mating, lambing and division of the flock into smaller groups according to the time of mating. This leads to an improvement in labour utilization and to overall management efficiency. Ewes and rams must be in good body condition at mating.

Replacement rams, selected as described earlier, should be used for mating at the age of 12 to 18 months. These rams should be checked before mating for general health. Physical examination should be made of the external reproductive organs particularly the testes. These must be well developed and free from obvious abnormalities and hardness. Examination of the semen under the microscope is necessary to determine the presence and concentration of spermatozoa and to evaluate their motility and freedom from abnormality. Semen samples are most conveniently taken by electro-ejaculation.

However, there is a variation in libido among rams with high fertility. This can be checked at an early stage with a small number of female animals. Younger rams are generally more active. The rams should be checked before the following mating season for high fertility and sex drive.

Rams should be sheared before each mating season, drenched and dipped for internal or external parasites and vaccinated against enterotoxaemia. Regular trimming of feet and horns should be carried out. Trimming the horns may be carried out with a dehorning wire or using a hack saw in older rams.

Good nutrition is necessary to maintain the mating ability of the ram. Supplementary feeding should be done during mating, consisting preferably of good legume hay or about 250 g of concentrates above the energy requirements for maintenance (which are about 15 percent higher than that of females or wethers of the same breed). A vitamin A injection is necessary before mating. Good body condition at mating is desirable but overfatness should be avoided because it reduces the animal's working performance. After mating all rams should be examined and a decision taken on which animals are to be replaced by younger rams.

Most sheep are seasonal breeders and the ewe's annual breeding pattern usually involves a period during which there are regular oestrus cycles followed abruptly by a period of anoestrus when cycling virtually ceases. Natural mating is practised during the breeding season or synchronization of the oestrus with the use of exogenous hormones employed with the objective of achieving a limited lambing period. During the anoestrus period exogenous hormones are used to induce oestrus.

Under natural mating one ram for 25-30 ewes is needed and when synchronization or induction of oestrus is applied one ram for 6-10 ewes, unless artificial insemination is practised. Provided that the necessary number of rams or artificial insemination services are available, flocks can be timed to lamb within a period of one week if lambing facilities and labour permit. Synchronization of oestrus is achieved by the administration of either natural progesterone or a synthetic progestagen compound, on an intra-vaginal sponge or as a subcutaneous implant 10-15 days prior to target mating. The injection of 500 IU of PMS on the withdrawal of the progesterone is given to ewes bred during the anoestrus period. For increasing breeding efficiency by shortening the frequency of lambing the most suitable system is lambing three times in two years.

The following systems of mating may be practised:

1. Hand mating - Teaser rams are used to run with the ewes for 15-20 minutes twice daily and to identify the ewes on heat. All ewes found by teasers to be in heat are separated into a smaller enclosure prepared from movable hurdles and near the individual ram pens (Photographs 6 and 7). Each ewe is mated to a certain ram to avoid inbreeding. A list of ewes to be mated by a certain ram is prepared before­ hand from the individual records of each animal. Each ewe is mated twice within 24 hours. If found in heat in the morning the ewe is mated once in the morning and again in the afternoon using the same ram. If found in heat in the afternoon it is mated once in the afternoon and for the second time on the following morning. With this method the time of expected lambing is known and the identity of the born lambs is also known. Unsuccessful matings of ewes during the mating season are identified by the teasers and the ewes are mated again. After the mating period teasers are used to run with the ewes to identify possible non-pregnant ewes.
2. Teaser rams with marking harness or painted brisket are run with the ewes all the time and marked ewes are removed from the flock to the mating enclosure thereafter using the procedure described earlier. This method is used when daily supervision is not available and also when it is necessary to identify ewes in heat during the night. The method is also used after the mating period, changing colours every 16 days in order to detect non-pregnant ewes.
3. Ewes are run in a group (25-30) with a single ram. Teaser rams with or without harness are used after the mating period in order to detect possible non-pregnant or problem ewes.

6. Rams in mating pens

7. Ewes identified in heat in the mating enclosure

Mating activity during the breeding period is higher in the morning and in the afternoon. In warm weather rams may be rested during the day and turned out with the ewes in the afternoon until the following morning.

An effective method of increasing the synchronization of naturally mated ewes is to run harnessed rams or teasers with the ewes at the end of the anoestrus period and start mating 15-20 days later. There is a delay in breeding of a lactating ewe which is more marked in the suckling ewe. For better long-term performance in an intensive system, weaning and/or cessation of milking should be timed so as to allow the ewe about 60 days of a recovery dry period before lambing.

4.4 Management of ewes and suckling lambs from birth to weaning

Ewes are moved the last ten days before lambing in smaller group pens with open yards. They are allowed to lamb and just after lambing are transferred to lambing pens (Figure 19). After the expulsion of the placenta the ewes and lambs are taken to a group pen where they are weighed (Photographs 8-11), lambs are ear-tagged (Photograph 11) and in addition to birth weights, the sex of the lambs is recorded. The hooves of the ewes are trimmed, the wool on the tail and hindquarters is sheared and the udder, water bag and legs are cleaned with water. The teats of the ewes are checked as to whether they are functional. Any surplus colostrum left after the lambs have suckled is milked by hand and either fed to other lambs, the mothers of which did not produce an adequate quantity of colostrum, or stored in a deep freeze for future use.

8. Recording of ewes' weight after lambing

9. A portable weighing scale

10. Recording of birth weight of lambs. The sling can also be used for larger lambs

11. Eartagging of lamb at birth together with weighing in a bucket

Figure 19 - Lambing pens. Prepared from movable hurdles. Side walls of 2 metres. Front doors of 1.2 metres. Height 1 metre.

Normal lambing should occur within 30-45 minutes after the rupture of the water bag. If it does not occur the ewe should be examined. Supervision during lambing is necessary to minimize lamb and ewe losses resulting from dystocia. Many of these losses can be avoided by giving timely assistance to relieve the dystocia. Immediately after birth membranes and mucus must be removed from the head of the lamb. Gentle pressure is applied on the ribs and blowing into the mouth of the lamb helps to stimulate breathing. The coat of the lamb is dried off and if chilly, heat is provided. The navel should be clipped with a pair of scissors and disinfected with a 7 percent iodine solution or any other appropriate disinfectant (Photograph 12).

12. Disinfection of lamb's navel

Lambs should be encouraged to nurse the ewe as soon as possible. The teats of the ewe should be checked to see that the teat canal is open or that the shape of the teat is suitable for easy suckling. Weak lambs may need assistance in nursing or it may be necessary to provide supplemental colostrum or milk (Photograph 13). The safest method of feeding a weak lamb is by a stomach tube (0.5-0.75 cm diameter) which can be inserted into the stomach and milk administered with a syringe through the tube.

13. Assisting lamb in sucking colostrum

The lambs should receive colostrum immediately after birth for three reasons:

The effectiveness of the transfer of antibodies from the colostrum depends on its antibody concentration, the level of intake by the lamb and the timing of consumption in relation to birth. A large quantity of colostrum (about 200-300 ml) should be consumed within 6-15 hours after birth because the ability of the lamb to absorb antibodies diminishes rapidly after the first 12 hours of life. Lambs which are very small or weak or the dams of which produce inadequate colostrum are bottle-fed supplemental colostrum. Frozen natural colostrum or frozen cow colostrum is thawed and warmed to body temperature and offered to the lambs. Colostrum deprivation can result in reduced performance and higher mortality under normal conditions.

A sufficient number of lambing pens is necessary. Ewes and lambs are penned for one or more days after lambing to ensure sound ewe-lamb pairings. Each lambing pen should have an area of 2-2.5 square metres and should have a solid floor and access to feed and water. These pens are movable and made from hurdles (Figure 20). Their number depends on the number of the ewes lambing at each time and the concentration of lambings (1 pen for 4-10 ewes). Orphans or lambs from multiple births or disowned lambs are fostered by ewes that have lost their lambs or put onto those with a single lamb. Fostering is more successful if the ewe and lamb are put in close confinement soon after the ewe is lambed.

Figure 20 - Hurdles. Prepared from galvanized iron pipes (left), usually for large animals, or frame from galvanized iron pipes, and woven or chain link wire (right). Movable doors (bottom left). Hurdles are placed in the ground (bottom right) with the legs of the hurdles placed inside.

Ewes and lambs after the colostrum feeding period are moved from the lambing area to other barns, older ewes suckling single lambs being kept separately from ewes suckling twins and separately from first lambing yearlings. There is a close association between the yield of milk by the ewe in early lactation and the growth of the lamb. During this period one unit of lamb liveweight will result from five units of milk consumed. The lamb becomes progressively less dependent on the ewe's milk as its solid feed increases.

4.5 Weaning

The weaning age of lambs may vary from four weeks to four months. However, when meat and milk are the primary objectives of sheep production,efforts should be directed to increasing both the commercial milk yield and the lamb carcass per ewe. In order to increase the milk yield,age at weaning should be reduced in association with a reduction in milk consumption by the lamb.

The advantages of an early weaning system are the following:

A system of weaning at 42 days of age may be applied. After the colostrum feeding period lambs are allowed to suck their dams at will until four weeks old. From the second week onwards roughage of excellent quality (alfalfa or other legume hay), a pelleted concentrate mixture containing 16 percent crude protein (as fed), and water are made available to lambs in separate troughs in the creep feeding area into which ewes cannot enter because of their size (Photograph 14). Barley grain and soyabean meal are the basic ingredients of the creep feed.

14. Lambs start on solid feed

Solid feed intake is very low until four weeks when the lambs are suckling at will. After the fourth week lambs are allowed restricted suckling for 8-10 hours daily. The lambs are separated from their dams in the afternoon and the following morning the ewes are milked first and then ewes and lambs are joined during the day. Solid feed intake is strongly influenced by milk intake and restriction of milk causes an early acceleration in solid feed consumption. By the time of weaning feed intake is adequate for maintenance and the growth of lambs.

Restricted suckling is applied to groups of lambs with eight days difference in age. When restricted suckling begins the age of lambs may range from 24 to 32 days and at weaning from 38 to 46 days. During the first four weeks ewes are checked once daily and surplus milk is removed by hand. After the fourth week the morning milking of ewes is carried out by hand or by milking machine. When hand milking is practised, miIking can be done in the barns or in the milking parlour where machine milking is also practised. Though lambs will not consume significant amounts of feed until the fourth week of age, the small amounts consumed at an earlier age are critical for establishing both rumen function and the habit of eating. An antibiotic (aureomycin) may be included in the creep feed (35-40 g/ton of finished feed).

4.6 Artificial rearing of lambs

Orphans, lambs from multiple births, mis-mothered lambs, lambs born to ewes with non­functional udders or low milk yields, weak lambs in their first week of life, or lambs born as twins to yearling ewes may be taken away for artificial rearing. Lambs should be removed from the ewes for artificial rearing on the first day if they have sucked adequate colostrum. Otherwise the lambs are fed colostrum from a bottle equipped with a teat. All lambs are first put in a pen for 2-4 days (the starter pen) where they are trained to nurse from the nipple bar. The trained lambs are then grouped by size and moved into the regular pens. Problem lambs remain in the starter pen for a few more days before being transferred to the regular pens.

There are two types of artificial rearing units. In the first type the artificial rearing unit is equipped with a variable number of individual pens. Each pen is 0.6 m x 0.3 m (0.18 m²) in size and is fitted with a milk feeder, water container and solid feed troughs. Hand feeding is practised. In the second type the lambs are kept as a group in pens. Milk is distributed through a pipeline system to individual nipples in the pen (large units) or, more frequently, the nipples are supplied from hard plastic containers filled daily.

The latter system is called the LAMB-BAR (Photographs 16-17) . It consists of a number of rubber suckling teats (nipples) each connected through a plastic tube with the liquid milk replacer. The upper side of the plastic tube should be inserted into the rubber drinking nipple. The lower side of the plastic tube is provided with a non-return valve so that after the first and following actions of the lamb, the proper vacuum in the tube will be maintained until the liquid milk replacer arrives in the mouth of the lamb. The non-return valve maintains the column of milk in the tube, and there is no return flow of the fluid. When the rubber nipple is properly fitted to the plastic tube there is practically no loss of milk by leaking. The lower end of the plastic tube (with the non-return valve) should be inserted into the drinking pail near the bottom. The non­return valve is needed the first week only.

15. Milk replacer is reconstituted to give a dry matter of 20 percent

16. Lamb-bar - Portable plastic container fitted with nipples

16. Lamb-bar - Portable plastic container fitted with nipples

17. Lamb-bar. Plastic container with milk outside the pen

The milk solution is prepared in a tank or other container where the appropriate milk replacer is diluted with only half the quantity of the water (water temperature about 50⁰C). This mixture is thoroughly stirred with a stirring rod. Then the remaining half of the water is added under constant stirring. Warm water is used only during the first week. Each pen holds 10-15 lambs (for better supervision), with a total area of 4-6 m² , there being two to three lamb bars with 3-4 nipples in each lamb bar. The container, nipples and plastic tubing should be washed daily.

The milk replacer should be of excellent quality and should contain 25-30 percent fat, 25 percent protein, 0.10 percent fibre, 5-10 percent ash, vitamins, trace elements, anti­biotic and antioxidant. Lactose content should be less than 50 percent. It should be stored in a dry place. The protein of the milk replacer should be derived from milk products. The replacement of milk proteins by other protein sources has not been very successful. Milk replacer is reconstituted to give a dry matter content of about 20 percent (Photograph 15). When one part of milk replacer containing 25 percent fat is diluted with four parts of water it gives five parts of milk containing 5 percent fat.

Increasing the dry matter content of the diluted milk results in a decrease of milk intake of the lambs and an increase in water intake, but there is no effect on overall performance .

About 8-10 kg of milk replacer is fed per lamb until weaning (42 days). The conversion of milk replacer to lamb liveweight. is about 1.2-1.4:1. Diluted milk replacer is fed cold twice daily. During the last two weeks (28-42 days) milk intake is reduced (feeding once daily in the morning) in order to promote a higher consumption of solid feed by lambs. Artificially reared lambs are offered the same solid feeds as those fed to the suckling lambs. When artificial rearing is practised the performance of the lambs on a particular milk replacer depends on the replacer's original quality and its quality at the time of feeding. The decision to use milk replacer depends on the price relationships between sheep milk, milk replacer, concentrates and labour. Under Near East conditions the use of milk replacers is recommended.

After weaning, suckling or artificially reared lambs remain in the same barn for one week before being moved to the growing unit. After the removal of each batch of lambs from the artificial rearing unit the whole unit is cleaned and disinfected.

4.7 Milking

Immediately after lambing the lambs are allowed to suck colostrum and any surplus quantity of colostrum is milked by hand and either fed to the lambs or stored for future use. With an early weaning system (6 weeks) and restricted suckling in the last two weeks ewes should be milked once daily in the morning. Even during the first four weeks when suckling is unrestricted the ewes should be checked and milked, particularly during the first ten days when milk intake by lambs is low. Hand milking during the first four weeks is practised, but during the last two weeks hand or machine milking is practised.

After weaning the milk yield of the ewes declines sharply, particularly in the case of twin suckling ewes, and more slowly thereafter. Ewes during this period are milked twice daily. Toward the end of lactation or when the milk yield of the ewes is low, hand milking once daily will save labour, milk yield being reduced only slightly.

Milking of ewes is stopped when the daily milk yield drops to 200 g daily. At this low level of production drying off the ewes is easy. However, the ewes are checked and milked completely once or twice if milk has accumulated in the udder. Ewes should always be dried off at least two months before the next lambing. When the milk yield of the ewes is high,drying off is applied gradually. Ewes are first milked once daily, then every other day, and then every three days. They are checked weekly for any milk accumulated in the udder. Simultaneously feed and water intake is reduced. It is preferable to isolate these ewes from dry ewes. Seven weeks before lambing "dry cow" therapy is applied if mastitis is a problem. Intramammary ointment is inserted in each teat to reduce the incidence of mastitis during the following lambing period.

Traditionally ewes are milked by hand. However, hand milking is a very laborious and time consuming job. For this reason modifications to the traditional facilities and practices are necessary in order to improve the working conditions and the efficiency of milking.

The milking parlour, located in a shed or a building, consists of a collection yard, where ewes are collected before milking, wooden or metal stands (Figure 21; Photograph 18) where ewes are milked and a second yard where ewes are held after milking. The ewes from the collection yard enter through a passage onto the stand. A ramp leads to the entrance of the stand and, after milking, the ewes are released through a hand-operated opening gate to a second ramp leading from the stand to the holding yard where the ewes wait until the milking is completed. The two yards may be prepared from hurdles or fencing. There are two or more stands in line and each milker while milking sits in front of each stand. Ewes are milked from behind and the milk is collected in a metal pail. The milking parlour area, including the stands and the metal pail, must be cleaned and disinfected.

Figure 21 - Milking stands. A wooden ramp leads to the wooden floor through an opening (45cm x 45cm). Another ramp leads from the opening gate to the collection yard.

17. Lamb-bar. The nipples are attached on a piece of flat sheet steel fixed on the inside of the pen

18. Ewe on a milking stand; machine-milked by a porable unit

The milker should wash his hands before and after milking and behave gently during the milking. The milker must check whether the milk is of normal composition. If there are any changes in the milk he should not continue milking, the ewe is isolated, the milker washes his hands with water and disinfectant and then continues the milking of other ewes. The isolated ewes are milked at the end of the milking period, milk samples are taken for laboratory diagnosis and veterinary advice is sought regarding any treatment. This procedure is also followed in the case of machine milking systems.

4.8 Machine milking

The aim of mechanical milking is to improve the working conditions of the milkers, increase their productivity and improve the quality of the milk. Milking ability of the ewes utilizing machine milking depends on the shape and dimensions of the udder and teats. Udder massage, machine stripping or hand stripping may be needed for the evacuation of the udder.

There are three main milking systems; the abreast or pit (Photographs 19 - 20), the rotary and the portable (Photograph 18) systems.

19. Milking parlour, pit system. Individual grain racks attached to the yokes (optional )

The abreast milking system or the pit system (Figure 22) has two levels with a difference in height between them of 90 cm. The milkers stand on the low level (the pit) and on the high level, on each side of the pit, the rows of yokes are mounted on a mobile framework (Figure 23). Whilst sheep enter the parlour the yokes are positioned at the far side and this allows the easy movement of the animals to enable them to find vacant spaces and lock themselves into the yokes (Photograph 20). After the sheep are all in position the whole framework is gently retracted toward the pit, either manually or by automatic means so as to move the sheep backwards and bring them up to the milker in a convenient position for milking. After removal of the clusters, the stalls are returned to their original position from which the ewes are released and replaced by the next batch. Usually a low level milk pipeline is used and occasionally a high level milk pipeline. Variable numbers of milking units are used to reduce the time of milking.

20. Milking parlour, pit system. Position of yokes before milking

20. Milking parlour, pit system.

Figure 22 - Milking parlour. Layout of the pit system. The pit is 90cm deep.

Figure 23 -Yokes. Details of the mobile framework and the yokes. Grain feeder is optional.

The rotary milking system consists of a rotating, raised, circular platform from the collecting area and up to a ramp from which the sheep walk onto the platform from the inside, facing outwards. The operators work in the central area. As the platform rotates the sheep are presented to the operator for application and removal of the clusters. The functions of the parlour are controlled from a centrally placed panel.

The portable milking system is a small mobile unit operating with a petrol engine or electric motor. It has two bucket units and enables the simultaneous milking of two sheep. The stands used for hand milking, abreast systems or low platforms may be used for holding the sheep.

Milking methods are based on the labour of two to three workers, one of them looking after the introduction of the sheep to and from the milking parlour. With all milking systems there are two yards, prepared from hurdles or fencing, one before milking for collection and one after milking, for holding until milking is finished, with narrow entrances and exit passages to the milking parlour. Strict sanitary conditions should be maintained in the milking parlour all equipment being washed and disinfected after each milking. Usually milking machines for sheep are operated with a vacuum of 44-47 kPa (33-35 cmHg), pulsation rate of 90-120 pulsations per minute and a pulsation ratio 50:50 or 40:60 (suction: massage).

4.9 General disease control measures

The economic loss to sheep production due to disease and parasites as a result of mortality, loss of condition, inefficient utilization of feed and carcass condemnation, is high. With the increasing intensification of sheep production the stress on the sheep's defences is more marked. This stress is the result of the higher productivity of the animals, the unusual diets they may be offered, the confinement of large numbers in small areas, and in sanitary conditions. Stress may develop from severe problems after storms or sudden changes in weather conditions, after sheep have been transported, sheared and trailed a long distance or following an abrupt change of feed. While planning to establish a sheep enterprise,sanitation and disease prevention must be a primary consideration.

Proper ventilation of the buildings, dry, clean pens, sanitary handling of the ewes and lambs, adequate and clean water, clean feed supplies and feeding facilities and the feeding of balanced rations, together with a vaccination and a parasite control programme are sound prophylactic measures for disease prevention and control in sheep flocks. Information on housing, construction of pens and feeding and watering facilities is given in Chapter 3.

Disease and health problems of sheep cannot be controlled or prevented if they are not identified. Every effort should be made therefore to determine the exact cause of death when animals die. Correct diagnosis of the condition causing the death will help to save many animals in the flock. If, for example, symptoms of diarrhoea appear in lambs, faecal samples (rectal swabs) are obtained for laboratory diagnosis in order to identify whether the condition is of bacterial, coccidial, parasitic or nutritional origin so that proper treatment against the causal agent can be applied. All ewes which abort must be separated from other ewes and the placentae and dead lambs removed and buried or burnt. Samples of placentae, the embryo and of dead lambs should be taken for laboratory examination in order to determine the cause of the abortions.

Disease may be carried from flock to flock by visitors, friendly farmers or sheep shearers. A disinfectant should be applied to injuries and in warm weather a fly repellent should be used. Sick animals should be removed from the flock to a separate or isolated pen where feeding and treatment can be done more easily.

There are many vaccines, antibiotic injections and other pharmaceutical products (as, for example, vitamins) available to producers that should be used when the need arises. Good care and the necessary sanitary measures should be applied when vaccinating or giving injections. Improperly administered vaccines and injections may cause infection, loss of weight and condition and lameness. Needles and syringes must be sterilized. Manufacturers' recommendations should be followed as to the dosage and means of injection. The rules of hygiene must always be observed. Cleanliness and disinfection are the only means of preventing and controlling the spread of infectious agents.

Subcutaneous injections are given just beneath the skin. These are administered most easily on the side of the neck, just behind the shoulders or on the wool-free area under the forelegs. Intramuscular injections are given directly into the muscle of the animal and in sheep are normally administered in the muscle of the shoulder or forearm. The needle should be inserted into the muscle and the syringe plunger pulled slightly backward to ensure that the needle point is not in a blood vessel. If it is in a blood vessel, blood will enter the syringe. The needle should then he pulled back slightly and the injection completed. Intravenous injections are made directly into the jugular vein along the neck.

The knowledge of existing disease problems in a particular area will help in outlining a programme of vaccination and control of internal and external parasites in that area.

Vaccines are used to develop prolonged immunity to specific diseases. Vaccines should only be given to healthy animals and in accordance with the manufacturers' directions. The instructions for the reconstitution, storage, administration and dosage should be closely followed. Expiration date should be noted and vaccines should not be used after this date. If vaccines are used improperly they may be completely ineffective. Active immunity is not established until at least 10 days following vaccination. Some vaccinations may require annual injections (booster doses) to maintain effective immunity.

Different vaccines and types of vaccines are available which can be used depending on the diseases present within a country, in districts within a country or in neighbouring countries. The vaccine against enterotoxaemia, for example, is given every year to breeding stock, suckling lambs (15-20 days) and again at weaning and in feeder lambs before transportation and when in the feedlot. Johne's disease vaccine is given to lambs at 7-10 days old. Foot and mouth vaccine is given after the sixth month of age and is repeated every year. Virus abortion vaccine (Chlamydiosis) is given to yearlings at least 15 days before mating and every two or three years thereafter. Sheep pox, anthrax and other vaccines may be given in areas where such diseases are present.

First aid materials for the personnel working on the farm and other pharmaceutical products for animal use are stored in a medical cabinet. A refrigerator is required for certain drugs or vaccines.

An isolation pen equipped with feeding and water facilities should be built in a corner of the farm. In this sick animals can be isolated to prevent the spread of disease from other animals and in this pen treatment is applied.

4.10 Control of parasites

The damage from internal parasites is normally greatest in lambs, yearlings and very old sheep. Proper nutrition is of extreme importance in the control of internal parasites. Parasitic disease problems increase with intensification of production and lack of attention to strict sanitation. A regular parasite control programme is necessary to prevent loss of condition of the animals and loss of production.

The main categories of internal parasites are the nematodes (stomach and intestinal roundworms, such as Ostertagia and Trichostrongyle,and lungworms), cestodes and trematodes. In all cases of parasitism more than one species of worm is present but usually the disease is due to one or two species. Laboratory examination is, therefore, required for the identification of the causal parasite(s) in order that the correct treatment can be applied.

The objective of seasonal plans of control is to reduce the number of worms at certain critical periods. Treatment at these periods aims at preventing the build-up of heavy infections in the animal and at reducing the contamination of pastures and sheds with worm eggs. Control of parasitism is accomplished through sound management and the use of drugs. Leakages of water supplied to reservoirs, tanks or troughs should be avoided. Overstocking for long periods should also be avoided. Strip grazing and clean rested pastures for lambs and drenched sheep should be used. The use of feed bunks and proper nutrition is essential in controlling parasitism.

Drenching is the most effective and least expensive method if proper equipment (Photograph 21) and techniques are used. Without adequate precautions being taken, sheep may be lost from injury, crowding in the drenching chute or from over-dosage. Pneumonia may result from drench in the lungs. Drenching should be done if possible during the coolest part of the day. If drenching must be done during the heat of the day it will be beneficial to sheep and labour if temporary shade is provided. A chute (race) for drenching should be about 50 cm wide and 12m - 15m long and the sides should be solid. The operator moves along beside the sheep inside the chute and stands just behind the shoulder of the sheep being drenched. The free hand should be placed under the jaw and the nozzle of the drench gun is inserted into the side of the mouth and over the tongue. The head should be held in a normal position. Different nozzle lengths are available for most drench guns depending on the breed of the sheep. The end of the nozzle should be just opposite the middle molar teeth and directed slightly toward the side of the mouth.

21. Drenching gun (top), multidose syringe (bottom)

Ewes in late pregnancy are not drenched. There are a number of dose syringes and drench guns that may be used satisfactorily. There is a variety of anthelmintics which is very effective. Manufacturers'recommendations as to dosage and instructions for their use should be strictly followed.

Infestation of sheep with ticks, lice and other ectoparasites may be widespread and cause considerable loss in condition and production and reduce the quality of the wool.

Ticks and lice are easily controlled by dipping, spraying or dusting with a suitable acaricide/insecticide. Permanent dipping tanks may be used for dipping (Figure 24). The application of an acaricide/insecticide, if possible, soon after shearing, can be done with the least effort and expense, the results being very satisfactory. Normally two applications a year will control ticks effectively.

Figure 24 - Dipping tank. Permanent dipping vat and footbath. Hurdles for fencing collecting yards.

Dipping is not recommended for sick animals, thirsty animals or animals after exercise and animals should not be over driven after dipping. Dipping is also not recommended for ewes in late pregnancy or within a short time before slaughter. Sheep are kept in the swim bath for half a minute and one minute if fleeces are over two months. Spraying isalso not recommended for ewes in late pregnancy or within a short time before slaughter. Sheep are kept in the swim bath for half a minute and one minute if fleeces are over two months. Spraying is not recommended in a confined, non-ventilated area. There are many commercial acaricides and insecticides suitable for the effective control of ectoparasites. A veterinarian's advice should be sought to choose the right preparation. Manufacturers' recommendations as to dosage, formulation and strength, the amount for each animal and where and when to apply them must be strictly followed.

4.11 Major diseases in sheep

There are many types of pneumonia in sheep such as parasitic, aspiration, viral and bacterial. Sheep of all ages are affected. Stress factors influence the severity of pneumonia. Some of the predisposing factors are extreme climatic conditions (excess moisture, faulty ventilation, draughts, and temperature extremes particularly at lambing and weaning), transportation, shearing and housing. Reducing the factors responsible for stress may reduce the incidence of pneumonia. Favourable conditions under which stress is reduced are:

If pneumonia is an annual problem with lambs, tetracycline antibiotics may be added to the concentrate ration. The broad spectrum antibiotics are usually effective as a treatment for pneumonia.

Enterotoxaemia affects sheep of all ages but it is most common in lambs under 6 weeks of age and weaned lambs in feedlots. The most obvious predisposing factors are digestive disturbances due to diet, lack of exercise and sudden changes in the diet. The disease may be prevented through good management and by vaccination. Lambs coming from pastures should be gradually adapted to feedlot conditions. Hay is fed the first few days and gradually concentrates are introduced. Feed must be available at all times.

Parasite control should first be implemented and then vaccination before transportation. Antibiotics may be added in the ration at 20 mg/kg feed. Providing the lambs are in good body condition booster doses should be given 2-4 weeks later after the arrival of the lambs in the feedlot. Intensively reared lambs require one vaccination during suckling and a booster dose at weaning or soon after weaning. Losses may be prevented in young lambs by vaccination of the ewe 2-4 weeks before lambing. If enterotoxaemia appears late in the feeding period concentrates are reduced by 50 percent for one week or longer after which they are increased gradually. Lambs in market condition are sold and those remaining vaccinated.

Polyarthritis is an infectious disease of nursing lambs, recently weaned lambs and feedlot lambs. Clinically the disease is characterized mainly by stiffness and swollen joints which lead to reduced weight gains. Antibiotics have proved to be effective for the control of the disease.

White muscle disease is a condition due to a selenium or vitamin E deficiency and is more common in lambs 3-8 weeks of age; it may, however, be seen in older lambs. When experience indicates that white muscle disease is an annual problem,the best results are obtained by injecting ewes with selenium and vitamin E one to four weeks before lambing and preferably by injecting lambs 2-4 days after birth and again at 20-22 days of age.

Coccidiosis, if not controlled, causes loss of appetite, unthriftiness, diarrhoea and high mortality. It is primarily a disease of young and feedlot lambs. Outbreaks may occur 2-3 weeks after lambs have arrived in the feedlot. Feeding low levels of coccidiostats is of great value in preventing an outbreak. Feed and water troughs should be designed to allow the minimum of faecal contamination. Troughs should always be clean. Sulphonamides are used for treatment.

The occurrence of urinary calculi may be widespread in sheep and particularly in rams or lambs in feedlots or on high concentrate diets. The condition is associated with a high phosphorus content in the diet, rations with a phosphorus-calcium imbalance and those with low water and a high mineral intake. Preventive measures are the provision of a clean, constant supply of water and a normal phosphorus content in the diet. When concentrate rations high in phosphorus are fed.it is advisable to add limestone (1-2 percent) to correct the calcium:phosphorus ratio.If the diet is alkaline lOg of ammonium chloride is added.

Staphylococci, streptococci, pasteurella and other organisms are implicated as causes of mastitis in suckling or milking sheep. The gangrenous type of mastitis is more severe and in those ewes which survive the udder is non-functional or severely damaged. Ewes affected with mastitis should be immediately separated from the flock and treated with a wide spectrum antibiotic. Sulphamezathine is particularly effective. All affected ewes are culled. Strict hygiene measures such as cleanliness, good milking and udder washing and dipping in appropriate disinfectant can prevent the outbreak of the disease. Injuries of the udder or the teats should be treated so as to prevent the transfer of infection during milking through the teat canal. When ewes are dried off milking is gradually discontinued. About seven weeks before the next lambing intramammary ointment (similar to that used for "dry cow") is inserted in each teat to reduce the incidence of mastitis in the following lactation.

4.12 Health problems of young lambs

Some of the most important causes of death in lambs during the first weeks of life are pneumonia, starvation and diarrhoea. The survival rate of lambs can be increased when:

The incidence of disease increases as the lambing season progresses, because there is an accumulation of infection in the lambing areas. Sound sanitary conditions must always be ensured in these areas in order to reduce the incidence of disease.

4.13 Nutritional disorders

A condition called hypocalcaemia, because the affected animals have a low blood calcium level, occurs normally within the first three days after lambing, during late pregnancy and occasionally in other periods. Affected animals stagger from side to side when walking, lie down on the sternum, show muscle tremors, fall into a coma and die. Predisposing causes may be the physiological upset at lambing, sudden starvation and bad weather conditions. With increasing age the calcium resorption from the bone is reduced and a continuous absorption of calcium from the digestive tract is required. In the early stages of the disorder the intravenous injection of calcium borogluconate alleviates the symptoms.

Pregnancy toxaemia or twin lamb disease occurs usually in twin bearing ewes during late pregnancy and is due to an imbalance between the energy demand of the foetuses and the energy intake of the ewe. It can be induced by undernutrition, impaired liver function and endocrine disorders. Prevention of the disease may be successful with the maintenance of a high level of feed intake by the ewe, no sudden changes in the diet and no sudden changes of the conditions under which the ewes are kept.

The clinical designation 'rumen acidosis' has to be considered as a collective term for several digestive disturbances which result in depression of the pH of the rumen contents. Acidosis may develop under the following circumstances:

In order to prevent losses from acidosis the following preventive measures are suggested:

The feeding of sheep with diets high in copper (over 25 ppm) over an extended period causes haemolytic jaundice and death due to copper poisoning. Excess of copper accumulates in the liver until at a critical level and affected by stress factors, it induces liver cell necrosis and liberation of copper into the blood stream. The disease may also occur when the copper content in the diet is 10-20 ppm and there are also extremely low levels of molybdenum (0.1-0.2 ppm). Copper poisoning may arise from the increased use of copper compounds by the veterinary services, the increased use of copper fungicides, mistakes in compounding (the preparation, for example, of sheep diets after the preparation of poultry diets high in copper or the use of a trace element mixture containing copper, more suitable for other types of animals). In cases of copper poisoning of sheep the recommended therapy is drenching daily for five days with 100 mg of ammonium molybdate and 1 g of sodium sulphate. Due to interaction in the metabolism of copper, molybdenum and sulphur, it is recommended that a daily intake of 10 mg of copper, 2-2.5 mg of molybdenum and 2-2.5 g of sulphur should be given as a preventive measure against copper poisoning.

4.14 Trimming of hooves, castration, docking and dehorning

Twice a year hooves should be trimmed using a special pair of scissors (Photographs 22 and 23). Trimming takes place immediately after lambing and later at least two months before the next lambing. A permanent foot bath should be constructed (Figure 24) to treat the feet of the sheep.

22. Dehorning wire (left), hand shears (right) and hoof trimming scissors (middle)

24. Electricshearing machine

24. Electric shearing machine

Castration of males is carried out before the lambs are 6 weeks of age using the elastrators, the knife or the Burdizzo method. However, castration is not recommended under intensive conditions of fattening where slaughtering takes place a relatively short time before sexual maturity. Castration reduces the rate of gain and feed efficiency and the carcass contains more fat compared to intact male lambs. Moreover, in most countries of the Near East, slaughter animals with intact testicles are preferred.

Docking of the tail should take place during the first days of life (2-4) using a knife or elastrators. However, there is no definite advantage to be gained from this operation (a better quality of carcass of males is claimed) since losses of lambs may occur from shock or infection. If instruments for docking and castration are not used properly and strict sanitation is not observed, loss of weight and condition, and death may occur.

There is no need to dehorn lambs which are to be slaughtered. In rams kept for breeding it is better to leave the horns and cut them using a dehorning wire (Photograph 22) as the need arises.

23. Trimming of hooves

25. Shearing after lambing

4.15 Fleece and shearing

In a sheep production system where the main objectives are the production of meat and milk the contribution of wool to the annual income is very small, wool being considered a by-product.

The wool yield and quality is affected by genetic and nutritional factors. Considerable breed differences in fleece characters exist mainly in the weight of the fleece and in its composition. Chronic undernutrition can reduce the growth of the wool and the thickness of the fibre. Feeding practices which do not restrict the birth weight or the early postnatal growth of lambs will help positively in the initiation and maturation of follicles. This development is necessary if maximum wool production is to be achieved. Increased feed intake results in higher quantity and quality of wool. The quality of wool is lower as a result of sudden and severe reduction in feed consumption brought about by drought, illness or lack of water. Adequate protein intake is also necessary. Infestation of sheep with ectoparasites reduces the quality, appearance and value of wool. Dipping or spraying against ectoparasites will, however, improve wool quality.

A sheep is usually shorn for the first time at about 10-15 months of age. Shearing takes place normally once a year in early spring.

Shearing of ewes and rams usually takes place after 15 March when temperatures begin to rise. Lambs should be sheared in June. Shearing can be done using either a special pair of hand shears (Photograph 7), or an electric shearing machine (Photographs 8 and 9). Combs and cutters or hand shears should be disinfected before use. A disinfectant should be applied to cuts occurring during shearing.

The wool is first cleaned by hand or dipping is scheduled a few days before shearing so that the wool is clean. Sheep are sheared by cutting the wool just above skin level using a pair of shears. Hand shears have been traditionally employed for this purpose, but the use of mechanically operated shears, particularly those powered by electricity, is becoming widespread. Machinery should be checked for damaged and worn parts and replacements, if necessary, ordered well before the scheduled shearing time. The shearing shed should be cleaned before shearing and skin cuts disinfected. Hand shears or electrical shears should also be disinfected. After shearing the animals should not be exposed to severe climatic conditions and should not be driven long distances. It is customary at shearing to separate the soiled wool and the floor sweepings from the main fleece which is preferably packed in hessian bags.

4.16 Record keeping

The overall efficiency of an intensive sheep operation depends on the improvement of the breeding efficiency of the flock (prolificacy, frequency of lambing, weaning percentage); proper nutrition of all animals (ewes, rams and lambs) and maintaining good health of the flock. The key to genetic improvement, balanced feeding and health control programmes is record keeping.

Productive traits such as prolificacy, milk production, growth rate, fleece weight, time and duration of the breeding season, adaptability and the results of selection or crossbreeding can best be evaluated when records are kept for each animal. The measure­ment of these characters demands the individual identification of all animals in the flock. The individual identification of the lambs requires the correct assignment of lambs to ewes at lambing time and the correct assignment of ewes to rams at mating time. Eartags of different types are available for individual identification. When ewe lambs or ram lambs have been selected to join the breeding flock larger eartags may be used. The simultaneous identification by tattooing the inside of the ear will help to keep the identification of the individual when eartags are lost.

Various books are kept on the farm for record keeping purposes:

Mating book. The following data is recorded: ewe number, first, second, third service, date of service and sire.

Lambing book should record: ewe number, lambing date, lamb number, sex of lambs, birth weight, sire, weaning weight, age at weaning and liveweight of lambs at 105 days.

All the progeny and production records are transferred to an individual sheep record card on which milk production, fat content of milk and lactation period are recorded.

Veterinary diary. This is a diary in which all cases of death, disease and treatment of animals are recorded daily. Date of vaccination, dipping and veterinary diagnostic tests are also included. Specimens for laboratory diagnosis (rectal swabs, milk, blood, placenta and embryo) and the veterinary results are also recorded.

Mortality book. All dead animals are recorded together with the results of the post-mortem examinations.

Records of feeding. The rationing of each category of ewe (dry, lactating, pregnant, ewe lambs and fattening lambs) is recorded on special forms so that personnel responsible for the feeding of the animals is aware of any changes in the rations (quantity and type of roughage or of concentrate mixture).

Milk records. The individual milk yield of ewes is recorded on special forms once monthly after weaning until the end of the lactation.

Records must be used effectively if they are to repay the trouble and expense of keeping them. They can help, for example, in the selection of replacements, the culling of unproductive animals and identification of health problems in the flock.

4.17 Feeding of the ewe

Feeding, in most intensive production systems, is responsible for over 50 percent of the total production costs. It constitutes therefore the most important factor governing the success of any intensive operation. Rations must be formulated which support optimum production, and are efficient and economical to feed. Energy intake is the most important factor in production. In practice the nutrient requirements are based on the performance of a group of animals. Feed allowance therefore must be adequate for all animals. It is also not possible to have one ration for each class of animal. Farmers may have one or two concentrate mixtures or supplements and offer different proportions of concentrates to roughage and/or roughage of varying quality, under different situations.

When ewes lamb once each year the time between weaning and mating should enable ewes to be brought up and maintained in good body condition for mating. More frequent lambing, or when ewes are milked by hand, may require the use of concentrate feeds or good quality roughage for such practices. Usually the onset of oestrus is delayed when ewes are lactating. Milking of first lambing ewes is stopped earlier than older ewes even at higher milk yields, because the onset of oestrus in this class of ewes is delayed. The condition of the ewe at mating has an important influence on the number of lambs born. There is a static effect of body size with heavier ewes producing more lambs and a smaller dynamic effect of improving body condition in ewes of similar weight.

Flushing is the practice of improving ewe body condition prior to mating by increasing the plane of nutrition. Flushing is usually accomplished by providing animals with fresh pasture, good quality hay or up to 0.25 kg concentrates per day. This feeding begins 2-3 weeks before breeding and continues through the mating season. Flushing is generally not profitable when supplemental feed is fed to ewes in normal body condition. Excessively fat ewes or those in very poor condition will perform at a reduced rate compared to ewes in normal body condition. The shepherd or the manager of the sheep flock usually is in a better position to judge the body condition of the ewes and decide whether flushing is necessary.

Pregnancy adds to the nutritional requirements of the ewes. After the ewes are mated and pregnancy is established it is sufficient to feed them for maintenance until the third month of pregnancy. Thereafter, and until lambing, the requirements increase because of the additional requirements of the lamb(s), udder growth and initiation of milk secretion. Pregnant ewes are fed separately from dry ewes. The plane of nutrition is gradually increased after the third month of pregnancy so that at six weeks before lambing the ewes are offered the full diet until lambing. It is advisable that changes of diet during this critical period are avoided. Grazing for 1-2 hours daily is necessary even if feed is not available in adequate quantities. Dry roughage should be offered first in the barn, before turning the ewes out for grazing. Roughage should always be offered first followed by the concentrate mixture. Usually diets of higher energy concentration (good quality roughage and concentrates) and of good palatability are fed.

Appetite declines at the latter stage of pregnancy and during this period the ewe may suffer a severe negative energy balance and pregnancy toxaemia may result. It is also advisable during the last stages of pregnancy for diets to be given similar to those used immediately after lambing, to avoid sudden changes of diet. The level of different nutrients in late pregnancy depends on the liveweight of the ewe, the number of foetuses and the type of feedstuffs used in the formulation of the diets.

Maintaining the required plane of nutrition in early lactation is important to increase total milk yield. There is no effect of the level of feeding during the last stages of pregnancy on the milk yield of the ewes unless the feed deficit is very large. Single bearing ewes only suffer from underfeeding when extreme weather conditions (drought) lead to a prolonged period of semi-starvation. Under good conditions undernutrition is likely to be evident in ewes carrying more than one lamb. Milk production can be severely affected by the level of feeding after lambing. The intake of ewes immediately after lambing is low and increases gradually. However, maximum feed intake does not occur until after peak milk yield and animals with high milk yields are in negative energy balance. For this reason diets high in energy concentrates are fed during this period. Better nutrition in early lactation will result in higher peak milk yield which is highly correlated with total lactation milk yield.

The diet of ewes should gradually increase from lambing to ten days post partum when controlled ad libitum feeding is practised. The increase in energy intake during this period and until weaning is mainly achieved by increasing the concentrate component of the diet. Roughage of good quality is offered (lucerne hay or other legume hay) but the proportion of concentrates to roughage should remain between 60:40 or 70:30 to avoid digestive disturbances. This high level of feeding continues for about one week after weaning.

Milk yield is reduced immediately after weaning. The feeding of ewes ten days after weaning to the end of lactation depends on the level of milk production of the flock and the fat content of milk, the liveweight of the ewes, the desired liveweight change, and the feedstuffs available. Feeding level is adjusted at 2 or 4 week intervals. The loss of liveweight occurs during the first 50 days of lactation and is more efficiently- restored during the lactating period than during the dry period. The flock may be divided into two groups according to the level of production and are fed accordingly. For each kilogramme of milk produced, with fat ranging from 6-7 percent, about 700-750 g of concentrates are fed. In mid and late lactation when milk yield is low feedstuffs of lower quality may be used.

Dry ewes have low requirements for the different nutrients, and roughages of low quality supplemented with nitrogen, phosphorus and vitamin A are adequate. Ewes in poor condition during this period must be fed extra feed to restore good body condition until mating. The requirements depend on the liveweight of the ewe and its activity during grazing. The energy cost of walking is about 2.6 Joules/kg liveweight horizontal metre and 28 Joules/kg liveweight vertical metre.

Ewes are fed roughages and concentrates either in fenceline feeders or are hand fed in hay or grain bunks. Sheep diets are balanced first for energy. Other nutrients in deficit are then supplemented.

In intensive sheep operations feeding systems are based on the concept of the determination of the nutrient requirements of the animal and the nutritive value of feeds, and then on the formulation of a ration which meets the daily requirements of the animals. However, grazing can play an important economic role in meeting part of the nutrient requirements of the sheep particularly when natural vegetation, stubble or crop residues are available over certain periods of the year. It is important to schedule breeding and weaning so as to obtain an optimum combination of the animal's nutrient requirements and forage availability and quality.

Production response of grazing animals is related to both quality and availability of feed. Sheep grazing on good quality pasture may obtain adequate levels of most nutrients, but deficiencies may be expected when grazing is inadequate and of poor quality. Supplementary feeding of low-quality roughages, mainly with nitrogen, energy, phosphorus and vitamin A, is necessary. Generally the amount and kind of supplement varies. The operator must be able to assess the condition of grazing, the condition of the sheep and be able to determine what supplements can be supplied at least cost to ensure adequate production.

Feed grade urea contains 45 percent N or 281 percent crude protein (NX 6.25). The amount of protein equivalent in 13 kg of urea plus 87 kg of maize is the same as in 100 kgof soyabean meal. Urea can be efficiently utilized in rations containing high levels of easily fermentable carbohydrates (grains, molasses), when the degradability of protein inthe rumen is low and the level of protein in the diet after supplementation is not higher than 12 percent crude protein (dry matter). It is not however efficiently utilized in moderate to high roughage diets. Good mixing of urea with the other ingredients is necessary to avoid possible toxic effects.

4.18 Water intake

Water is essential to successful sheep production and producers must plan for an adequate supply of clean water when designing their sheep operations. Water quality is of great importance to sheep. Sheep will not consume adequate amounts of stagnant, poor quality water or water that has an objectionable odour. If sheep are forced to drink poor quality water, production will be greatly reduced.

Water intake increases as dry matter intake increases. Water intake is about twice the weight of the air dry feed intake. Intake of excessive nitrogenous compounds results in considerable water loss in the elimination of the nitrogen-end products. Excessive mineral intake will significantly increase water consumption.

Sheep can tolerate water containing 1 percent salt over a relatively long period of time but cannot tolerate water containing 1.5 or 2.0 percent salt. Sheep apparently can use water containing 1.3 percent salt without ill effect., but water consumption increases up to 100 percent.

Sharp increases in water requirements can be expected when environmental temperatures rise above 21° C and water intake decreases with low environmental temperatures. The temperature of the water will have a great effect on water intake during periods of extreme heat or cold. Water located in the shade will be accepted more readily on extremely hot days. Water requirements and water intake of the ewe increase greatly during late gestation and during lactation. For greatest production during these periods ewes must have an unlimited water supply available from which they can drink frequently.

Adequate watering facilities to prevent crowding and to ensure that each animal receives ample water is essential.