The Systems of Sheep Production
Intensive sheep production aims at obtaining two lambing per year and achieving high growth rates. Breeding and reproduction management should therefore receive proper attention. This involves the adoption of a number of simple, yet highly essential practices based on knowledge of
the reproductive physiology of sheep.
To start with it is good husbandry practice to separate male and female lambs after weaning and to raise them in separate opens or buildings this will prevent indiscriminate breeding and facilitate breeding during specific periods of the year.
Male lambs attain breeding age at about nine months while female lambs attain breeding age between five to eight months however rams should not be used for breeding until one and half yearof age when they would be more efficient in serving more females due to greater development of their sperm reserves.
Likewise, female lambs should also not be bred until they are nine to twelve months old when they will be big enough to carry a pregnancy with less difficulty it is good practice to replace breeding rams with newly selected ones after each breeding season or at the least ewes may however remain in the breeding flock for four to six years to lambs by older ewes.
Rams to be selected for breeding should preferably have been born as twins (only one member of a twin pair should be selected to high body weight at weaning and six months. A minimum of six rams should be used in a flock of one hundred ewes to minimise inbreeding. Breeding ram should be given better feeding from at least six lambs by older ewes.
Rams to be selected for breeding should preferably have been born as twins (only one member of a twin pair should be selected to minimize inbreeding) and should be from among those that attained high body weight at weaning and six months. A minimum of six rams should be used in a flock of one hundred ewes to minimise inbreeding.
Breeding rams should be given better feeding from at least six weeks before they are intended for use. The estrous cycle in sheep is 16 to 17 days and the duration of estrus is one to two days.
Means that the ewe will accept to be mated by a ram for only one to two days in each cycle of 17 days this is the estrus or heat period. Ewe will normally ovulate (that is, produce an egg) shortly after the onset of oestrus (about 16 hours later) when breeding the whole flock by introducing rams for a period (flock mating).
The breeding rams should be left with the ewe flock for six to eight weeks (equivalent to about three oestrous cycles) to ensure that all ewes are bred. They should be withdrawn after this period.
Rams should be joined to ewes for breeding as from two weeks after lambing the ewes will still be nursing their lambs at this stage but this does not prevent them from getting pregnant if lambing extends over several weeks the ewes can be separated for rebreeding in batches according to their lambing dates.
Ewes may be synchronised for breeding about two to three weeks after lambing, using progestagen sponges. Synchronisation helps to reduce the spread in breeding dates and slightly shortens the rebreeding interval (period from lambing to subsequent conception) of ewes.
The treatment is simple and consists of vaginal insertion of one progestagen sponge per ewes for 12 days within two to three weeks after lambing. In order to improve ovulation rate breeding rams should be introduced to the treated ewes two-day before the sponges are withdrawn, mating will not commence until after the sponges. Oestrous is usually spread over four days after sponge removal. Non -pregnant ewes usually return to oestrus 16 to 21 days after sponge withdrawal.
Gestation period or pregnancy duration in sheep is about five months or 152 days. Ewe failing to lamb on two occasions, those weaning lambs of poor weight and old ewes (above seven years) should be culled (that is, removed from the breeding flock).
Nutrition exerts a big influence on reproductive performance in sheep. Under-nourishment during late pregnancy may cause pregnancy toxemia (a metabolic disease), low birth weight of lambs and poor lamb survival.
Under-nourishment during lactation and rebreeding may result in depressed lactation, delayed oestrus, lowered ovulation rate and poor fertility. Poor nutrition at this period also increases lamb and ewe mortality rates up to weaning, and in addition, results in lowered weaning weights in lambs that survive. Under good nutrition and management, at least 80 per cent of ewes mated should lamb with about25 per cent of the ewes producing twins.
Identification of individual animals facilitates many breeding operations such as selection of replacement stock and in the culling of unproductive animals. Metal or plastic ear tags are ideal for this purpose but where these are not available, wooden tags with numbers painted on them may be hung around the animals’ necks. Such identification helps proper record keeping.
Feeding
Sheep must be adequately fed for optimum performance. Poor feeding is one of the major factors limiting productivity. Essentially, feeds contain energy, protein, fibre, minerals, vitamins and water
Energy is present in feedstuffs in the form of carbohydrates, fats and oils. An animal must have sufficient energy to maintain its body functions and produce meat and milk. Grains, molasses and brewers dried grains are good sources of energy.
Proteins are essential for the repair of worn out tissues and the building of new ones. Young and nursing (milking) animals in particular need proteins. Oil seed cakes wheat offal and legume hays (harawa) are good sources of protein.
Fibre is made up of cellulose. High fibre feeds are commonly known as roughages .Ruminants extract energy from fibrous feeds.
Minerals and vitamins are essential for body functions and health of animals. Although all feedstuffs contain some amount of minerals and vitamins nevertheless mineral salt licks, bone meal and local rock salts are major sources of these nutrients and should be added to locally
compounded feeds.
Water is essential for the maintenance of body temperature and functions therefore water must always be available to animals.
The most commonly available feedstuffs for livestock are roughages (grasses legumes, browse plants and crop residues), oil seed cakes (cottonseed cake, groundnut cake and palm kernel cake), molasses wheat offal rice bran, dust (local bran) and brewers dried grains.
Roughage is the cheapest feed for sheep being ruminants this can be derived from rangelands (natural vegetation), sown pastures fallow lands and crop residues. For an intensive sheep production system, pasture establishment is a good investment, as a well-established and well-managed pasture will provide good quality feed (fresh grasses and legumes or hay).
This will considerably reduce the amount of concentrate supplements and hence the production cost. A well-established and well-managed pasture can support 25 to 40 sheep per hectare under grazing in the wet season and 5 to10 sheep per hectare in the dry season. The quality of pasture deteriorates considerably during the dry season, often requiring supplementation with concentrate feed.
The amount of concentrate to be utilised will largely depend on the quality and quantity of roughage available. A rule of thumb guide is to allow the animals to graze for at least 6 hours daily or be given 1.5 kg of good quality hay per head per day. In addition, the animals should each receive 0.2 to o.5 kg concentrate supplement per day. Ewes in late pregnancy and nursing animals should receive the higher level of concentrate.
Read Also: Strategies for Improving Cattle Production
Concentrate feeds for ruminants are now marketed country-wide in 25 or 50 kg bags. It may however be cheaper to compound your own concentrate feeds. Examples of 3 formulated rations are given in the section on feedlot fattening of sheep.
Sheep require two to six litres of water per day, depending on age, physiological status, and type of feed and ambient temperature. Both water and mineral salt licks should always be available to the animals.
Housing, Equipment and other Facilities
Housing is an essential requirement for intensive sheep production. Apart from providing overnight shelter and security for the animals it also provides protection against rain and cold. Housing also enhances close supervision of the flock. In short, provision of housing leads to an overall improvement in the performance of the animals.
Sheep houses need not be elaborate and can vary in type from a low mud-wall building with thatched roof, through corrugated iron walled building, to brick or block housing. Such housing should be located on well-drained soil and should be well ventilated to avoid dampness.
The floor can be cemented or made of rammed earth. The floor should be easy to clean and should be covered with suitable bedding material such as straw or wood shavings, which can be changed from time to time.
The building may be divided into pens. Floor space requirements for lambs and adult sheep are about 0.4 and 1.7 m2 respectively. In addition, floor space should be provided for feed and water troughs. There should be a minimum of three pens, one each for male and female sheep, and a sick pen. Ideally there should be more pens per building or more than one building, with separate one for males, females and weaners.
A store and a hay barn could form part of the building. Alternatively, the hay barn could be a separate structure. A run (enclosure) made of chain-link wire, waist-high, may be constructed in front of the pens, divided into at least two sections for males and females if housed in different pens in a single building.
Water supply can be from a well, tap, and bore hole or river. It should be clean and in sufficient quantity.
Feed and water troughs should be provided in every pen, either built-in or moveable type. A rectangular feed trough measuring 4 x 0.3 x 0.15 m is adequate for 10 adult sheep. Simple feed troughs could be made by cutting a drum lengthwise into two halves.
If cut drums are used, the edges should be made blunt to avoid injuries to the animals. Large plastic basins are better as water troughs as age unlike metal drums they do not corrode.
A foot-bath is required for the prevention and treatment of foot-rot, a very common problem with sheep on wet grounds. The most common type is the walk-through type which is a shallow, long receptacle. Where a small number of sheep is involved, a bucket of basin may be used.
A dip is an essential structure in a sheep farm. The walk-in, short-swim type is the most common. In this type, the animal enters the vat through a walk- down ramp into a deep section of the vat which contains the dipping solution, and swims out. Dip vats are best made with concrete.
A vat measuring 6 x 1.2 x 0.75m has a capacity of about 2000 litres. It is necessary to put a roof over the vat to prevent rain from diluting the chemical. In small-sized flocks, a 200-litre drum opened at one end can be used. The animals are immersed, one at a time, in the dipping solution contained in the drum for about 30 seconds. A knapsack sprayer can also used.
Routine Health Management
Routine flock health management is very important in an intensive sheep production system if mortality is to be kept at a reasonably low level. Advice in this regard should be sought from the nearest veterinary department of the Ministry of Agriculture.
Significant common diseases of ruminants are as follows:
• South-west zone: PPR (or kata), pneumonias (viral andbacterial), trypanosomiasis, helminthiasis, coccidiosis, bacterial infections and ectoparasites.
• South-east zone: PPR, pneumonias, trypanosomiasis, helminthiasis, ectoparasites, bacterial diseases and coccidiosis.
• Northern zone: pneumonias, trypanosomiasis, helminthiasis, ectoparasites, bacterial diseases, ectoparasites, skin disorders and coccidiosis.
The most basic health precautions are provision of adequate nutrition and maintenance of pen hygiene. Animals on low plane of nutrition are more susceptible to diseases than well-fed ones. Sheep pens should be cleaned at least once a month and periodically disinfected.
Overcrowding should be avoided. Sick animals should be transferred to a sick or isolation pen for proper veterinary care to reduce chances of infecting other animals. Newly purchased animals should be properly quarantined before introduction into the main flock.
PPR, which is a major disease especially in the southern parts of the country can effectively be controlled though vaccination.
Helminthiasis and ectoparasites can be controlled by routine de-worming and tick baths. Their importance varies from farm to farm depending on grazing management as well as between seasons. These diseases are more prevalent in the rainy season. Routine deworming
with anthelmintics and tick-baths with acaricides should be carried out once in three months during the dry season depending on the severity of the problem.
The farmer should ensure that lambs receive colostrums from their dams after birth. The navels of newly born lambs should be swabbed with iodine tincture. Coccidiosis tends to become a problem in newly weaned lambs and should be treated against as advised by a veterinarian.
In general, it is good practice to do the following:
1. Maintain environment sanitation especially in pens
2. Adopt good internal and external parasites control measures.
3. Observe the flock closely early in the morning and at other times for early detection of sick animals
4. Isolate sick animal and seek prompt veterinary attention for diagnosis and treatment.
5. Keep proper health records and have animals that died autopsied.
6. Keep newly purchased animal under for 30 days if possible before introduction into the main flock
7. Provide mineral salt licks and clean water in pens always.
8. Ensure that animals are receiving adequate and balanced ration.
9. Where pastures have been established rotational system of grazing between paddocks should be enforced to avoid build up of parasites on pastures.
10. Trim hooves and horns when necessary.
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