Sheep production is becoming more popular in Zambia and the prices of small stock are increasing at livestock auctions. This month we start with a brand new series, taking an in-depth look at everything about sheep farming.
We thank the ARC Institute for Agricultural Engineering in South Africa for making their manual on sheep production and facilities available to the readers of ProAgri Zambia.
In order to produce mutton economically, it is necessary to comply with certain basic production requirements. Various closely related factors have an influence on the production process. Optimal production is only possible if all these factors assert their influence separately and combined.
The design of an intensive production system is discussed according to a planning procedure, the climatic requirements, design specifications and choice of the site based on practical information, especially regarding the layout of the system. The various facilities such as the housing facility, the handling complex and shearing sheds are fully discussed in respect of the lay-out and existing systems.
The most important production requirements are the following:
- The provision of efficient and effective holding and handling facilities
- The establishment of proven genetic material resulting in proven stock
- The provision of a nutritional standard of high quality
- A high standard of management
- Stable marketing facilities
Existing production systems and the production cycle of sheep
Existing production systems for mutton production can be divided into two main groups, namely extensive and intensive systems. Other important aspects are the type, placing and construction of fences and gates. Provision must be made for sufficient drinking water and supplementary feeding.
In an extensive production system sheep live of the veld. Relevant structures therefore consist of drinking troughs, overnight facilities and a handling complex.
To prevent any confusion, the term intensive is defined as follows: Intensive sheep production is a system not defined under an extensive system and usually refers to a closed system, or a system which exists in a feeding pen or a production system from planted grazing or a combination thereof.
The final choice between the systems will largely depend on the owner or client, and will therefore depend on preference, management level, existing facilities, et cetera.
With intensive production systems there are two types of lambing seasons, namely an in-phase and accelerated lambing season.
In-phase lambing season
In this system each ewe lambs only once a year. The group is, however, divided into two, so that the ewes from different groups will lamb at different times of the year.
Risks are diminished this way, and lambing pens and feeding pens can be used more effectively. An existing system can be utilised to its maximum by extending the size of the herd.
Accelerated lambing season
The accelerated lambing season system is beginning to become a possibility as the production system is refined. Costs and risks of the system are usually high, but the potential income is also higher. In this system, sheep breeds with a long breeding season is used. The lambs are weaned early (six to eight weeks or on approximately 20 kg) and the ewes are tupped again immediately. Three lamb harvests in two years are obtained this way.
A typical lay-out of an intensive production system for both in-phase and accelerated lambing season systems can appear as shown in Figure 1.
A number of variations can occur, depending on how the planted pastures are integrated in the system and the facilities. A schematic lay-out of a system, which uses plenty of planted grazing and where the ewes lamb on the pastures, is presented in Figure 2.
This lay-out could be used where ewes lamb in the spring and/or autumn, but it will depend on the climate of the region in question. Regions with a reasonably dry, warm climate will be suitable for this type of lay-out.
Choice of breed
Under the item accelerated lambing season production system there was mention of breeds with a long breeding season. The specific breed to be used, will therefore also have an influence on the system to be used.
The objective of any intensive production system is maximising profit. It is therefore important that the choice of a breed will also be made with maximum profits in mind.
The term profit maximising refers to striving towards maximum income from mutton and/or wool production per ewe per year. Factors such as a personal preference for a certain breed are therefore excluded from this discussion.
In line with the profit maximising objective, the following factors pertaining to choice of breed are important:
- Adaptation of a breed to the specific region
- A long breeding season
- An acceptable carcass
- Growth potential
- High reproduction tempo
- Good maternal characteristics
If a certain herd size is accepted, the above factors can be evaluated according to three basic factors for the increase of mutton production, namely:
- Herd structure
- Age structure
- Weaning percentage
The herd structure pertains to the percentage of division of breeding ewes, she-lambs, young ewes and wethers. The analysis of the herd structure showed that an increase in breeding ewes has a very important influence on the future mutton production of a herd.
Factors such as marketing age, mating age and number of breeding seasons per year – which is directly dependent on the breed – determine the percentage breeding ewes in the herd. The greatest percentage breeding ewes in the herd – and consequently the highest mutton production – is possible with breeds such as mutton, mutton/wool and fur sheep.
Mutton production consists of the number of lambs and number of ewes marketed annually. An extension of the period that breeding ewes can be used in the herd means a reduction in the replacement tempo, that is the number of lambs to be retained in the herd per year for replacement of productive ewes. A reduction in the replacement tempo will inevitably ensure an increase in the number of marketable lambs per year and hence an increase in income.
Factors which influence the production period of breeding ewes are:
- The number of lambs weaned, mated per ewe, increasing to the ewe’s age of five years, after which it decreases as the ewe gets older;
- The survival age of the ewes remains constant to the age of seven years after which it decreases.
An early mating age and longevity of ewes are therefore very important factors to consider in the choice of a breed.
The weaning percentage directly determines the mutton production and can be increased by:
- An increase in the lamb percentage, that is the number of lambs born per mated ewe.
- An increase in fecundity: Under fecundity (fertility) we understand the number of lambs born per ewe. The occurrence of multiple births therefore has a positive influence on the meat production. There is, however, a notable weaker growth with multiples compared to single lambs. An increase in fertility must therefore be coupled with selection for better growth potential to be significant. Fecundity can be increased by selection within a breed or by crossbreeding.
- An improvement in the covering: That is the percentage ewes lambed per ewes mated. The fertility of the ewes and rams are very important here.
- An improvement in survival: That is the number of lambs born per number of lambs weaned. As far as the choice of a breed is concerned, the maternal characteristics are important here.
- An increase in lambing frequencies: That is that more coverings are done; three times in every two years instead of the normal annual lambing.
The above factors determine the number of marketable lambs per year. It is, however, also important to look at the factors that influence the total mass of lamb produced per year.
These factors are as follows:
- Milk production of the ewes: This feature largely determines the pre-weaning lamb growth and is especially important with a high fecundity characteristic.
- Growth potential of the lambs: The growth potential of the lambs is to an extent influenced by the heredity of this feature and varies from breed to breed.
- The “type” and carcass quality: has an anticipatory value to predict the percentage fat and percentage good meat cuts of a carcass.
The variation of the factors influencing the choice of a breed is sometimes greater within a breed as between different breeds. This means that no universal breed can be recommended for intensive systems.
Fundamentally, factors such as adaptation potential, fast growth and longevity of ewes, determine the choice of the breed. If the current wool price is considered, a further determining factor, namely the wool production potential, is also important.
Next month we shall look at the design of sheep production systems. Published with acknowledgement to the ARC Institute for Agricultural Engineering for the use of their
Sheep Facilities Manual. Visit www.arc.agric.za for more information.